CA2177141A1 - Packet data transmission with asynchronous bandwidth switching - Google Patents
Packet data transmission with asynchronous bandwidth switchingInfo
- Publication number
- CA2177141A1 CA2177141A1 CA002177141A CA2177141A CA2177141A1 CA 2177141 A1 CA2177141 A1 CA 2177141A1 CA 002177141 A CA002177141 A CA 002177141A CA 2177141 A CA2177141 A CA 2177141A CA 2177141 A1 CA2177141 A1 CA 2177141A1
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- Prior art keywords
- packet
- channel
- digital
- packet data
- transmission path
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0478—Provisions for broadband connections
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/64—Hybrid switching systems
- H04L12/6418—Hybrid transport
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J2203/00—Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
- H04J2203/0001—Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
- H04J2203/0064—Admission Control
- H04J2203/0067—Resource management and allocation
- H04J2203/0069—Channel allocation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/64—Hybrid switching systems
- H04L12/6418—Hybrid transport
- H04L2012/6445—Admission control
- H04L2012/6456—Channel and bandwidth allocation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/64—Hybrid switching systems
- H04L12/6418—Hybrid transport
- H04L2012/6445—Admission control
- H04L2012/6459—Multiplexing, e.g. TDMA, CDMA
Abstract
A packet data transmission node is switched asynchro-nously without interruption of data transmission and with a min-imum of circuit complexity. In particular, a packet channel is permitted to "breathe", gaining bandwidth when additional band-width becomes available from other temporarily unused digital channels and losing such addition bandwidth when such unused digital channels revert to other use. To permit such uninterrupted asynchronous operation, a "pad" or "throw away" character is de-fined which is ignored or discarded when it is received by another packet network node. Such a "pad" or "throwaway" character is unique only in the sense that is is distinct from and may not be confused with characters or bytes which may occur in normal data transmission sequences.
Description
~ ~ossnss70 2 1 ~ 7 ~ r~
p~rT~T~T nl~T~ ~RD~ MT.q.qIn~ WITH ~q~T~ TTq T~DWTnTI~ SWIT-'tTT~
Fi~1 ,i of th~ Tnvf~nt i nn This invention relates generally to packet data 5 trAn~ a; on systems and, more particularly, to packet data i aa; nn systems in which bAn~lw~ th i9 switched between packet i qai nn rhAnnc~l q and other t a~;nn rhAnn.~la which may themselves be voice L 'aainn rhAnn~la, L aainn channels in the form of multiple voice trAnr~;aainn rhAnn~lq, or additional packet data L alqinn rhAnn~l q.
T~AI l,~l "ll~l of th-~ Tnv.--nt;nn In modern day digital tPl:- ications~ the b~rkhnno for a packet data network is typically a T-1 15 Carrier digital i qa; nn line or its equivalent . A
T-1 Carrier digital L - as;on line opF~r:~tPa at a bit rate of l . 544 megabits per second, providing a total b~nrlW;~th of 1.544 M~Iz, and normally gupports 24 time division mult;rl-~Y~l digital DS0 rh~nn~la. Bach of these 24 digital DS0 rh~nn~l a has an effective bit rate of 64 kilobits per second, providing a hAnrlw; dth of 64 K~z each. A typical packet network; nrl l~d~q a plurality of s~rAr~te packet network nodes, coupled to one another by T- 1 Carrier digital ~_ ~ainn lines or their Z5 equivalent.
A packet network node generally opPr~t~a to assign a plurality of T-1 digital DS0 rh~nn~l a to form a hroader band packet data L a,ainn channel, leaving the L~ ~n;ng digital channels to be used either by additional packet data L_ ' aainn rh~nn~l a or as such s~p~rAte and distinct time division multiplex circuit switched rhAnnP1 a as voice or channels in the form of multiple voice rh~nn~l a. Becau_e such additional time division multiplex rh~nn~la as _Pr~r~tl~ voice channels or rh~nn~la formed by multiple voice channels may sometimes be inactive, it can be useful to make their unused bandwidth available temporarily to increase the bandwidths available to active packet data ~ qf~inn rhAnnf~ln In the pa5t, ~uch t~ r;ly unu8ed bandwidth has been r~Al 1 ocAted either ~Iy~ullLu-lOuuly or auy ~ 11L U~ ~uugly .
In syn.:llLul,uus r~llor~t;nn, frame random access ~ (often called, more simply, frame RAMs) rnntA~n;n~ digital channel allocation infnrr-t;nn in packet network nodes at both ends of a T- 1 Carrier tr~nP~ 3;nn line need to be reconfigured 8; ltAn~ollcly in order to ensure cnnt;m~o~lq flow of data. In such aLL~. ' q, a second frame is typically developed with all changes incorporated within it at both source and dest~nAtinn nodes before a signal from the source node to the dest~nAt;nn node sper;f;~q when to change the frame.
Synch~ulluu~i reconfiguration tends to be highly complex and ~ -~1n~ of memory, part;rlllRrly when more than one packet channel is involved.
Past asynchronous reconfiguration terhn;r~ require that ;nt~rnr~ l packet data t~--- q8;nn be ;ntorrllrt~l each time a frame RAM reconfirJurAtinn at opposite ends of the t 'qqjnn 8y8tem take8 place. Typically, packet data buf f ering is re~uired each time the f rame is reconf igured. Such asynchronous bandwidth switching also becomes an increasingly complex procegs a8 Afl~l;t;nnAl digital rh~nn~l A are reallocated, particularly if more than one packet channel is involved.
S ry of the Jnvention The invention permits bandwidth in a packet data trAnr--; ~qinn system to be switched asynchronously without interruption of data trAnn~;qq;on and with a minimum of 30 circuit complexity. In particular, a packet channel is permitted to "breathe~, gaining bandwidth when Aflrl;t;nnAl bandwidth becomes available from other t~ ~ r;ly un:u8ed digital rhAnnPl q and losing such additional bandwidth when such digital rhAnn~l q revert to other use. Frame 35 RA~s in packet network nodes at both ends of a T-l Carrier digital L ' ~:,q,; nn line no longer need to be reconf igured simultaneously . To permit such uninterrupted a~yl~ullLulluu8 op~rAt;nn, a ~pad~ or "throw ~ wo95ngs70 2 l 7 71 ~
awayn rh ~r;3ctPr i5 de~ined which i8 ignored or discarded whenever it is received by one packet network node f rom another. Such a "pad" or "tllL~ ~" character is unique in the sense that it is distinct from and may not be 5 ~ r ,~ 1 with rh~rærtPr~ or bytes which may occur in normal data ~_ ~8; nn 8~Ue:L~Ce8 .
The invention ~ v~:r~ - problems PnrollntPrPrl in the past by permitting packet traffic to rnnt;nllP flowing as h::lnrlw;~lth reconfiguration or gwitching takes place.
lO Packet data rnnt;nllP to propagate at a rate consistent with the smaller of either the previous or the next packet band conf iguration while bandwidth switching occurs . The rate at which packet data f low during bandwidth switching is, in other words, either the rate 15 ; ' ~tPly prior to or the rate; ''AtPly after bandwidth switching, tlPr~nr9;n~ upon which configuration allows f or le~s packet bandwidth . ;3andwidth switching may be completed in as little as a single frame and each reconfiguration is controlled by ;r~tion between 20 packet nodes, thus Pl ;m;n;~t;n~ any need for Pl~horlte frame synchronization methods.
The invention, f rom one ; ~ LdllL aspect, takes the form of an asyn~ u~ly reconfigurable packet network node having a transmitting portion f or transmitting 25 digital message data to another remote packet network node over an out~;n~ digital tr~n^~~;nn path and a receiving portion ~or receiving digital message data from the remote node over an ;nl n~ digital tr:~r- '~ginn path. Each of the digital tr~nF~ i nn paths employed 30 with such a reconfigurable packet node consists of a predetermined number of time division multiplexed digital rh~nnPlR Each of the time division mult;r1PYP~l digital rh~nnPl ~ has active and inactive states r9PtPrm;nPd by respective digital channel connect and ~; ~cnnn-~ct 35 re~uests. In standard tele r~t;nn~ tprm;nnl~gyl a connect request causes a channel to shi~t from an inactive state to an active state, while a ~ ronnPct W0 95129570 2 ~ 7 ~
request causes a channel to shif t f rom an active state to an inactive state.
From another important aspect, the invention takes the f orm of a method of operA t; n~ one or more such asynchronously reconf igurable packet network nodes .
In an a~y~ u~ ~uusly reconf igurable packet network node constructed or opPrAtPrl in Arcr~rflAnre with the invention, n of the digital channels in the outgoing L QQ~ on path are A~5i~nPd to a packet data channel, where n is an integer equal to or greater than zero, and connect and rl; QCr~nnPCt requests are ~lPtected to signal shifts of any of the digital rhAnnPl Q in the outgoing ~ 'qQ;nn path between respective active and inactive states. PrP~lPtPrm;nPd pad rhArAotprs ignored by a remote or dest;nAt;rn node are transmitted in any of the digital channels in the outgoing t---- QQirn path in L~ff~uuse to ~lPtect;on of respective connect or disconnect requests.
A channel rPAQsi_ initiation signal is transmitted to the remote node over the outgoing t---- ' QQ; on path and a channel rPA~QiS acknowledgment signal is received f rom the remote node over the incoming t ' Qsir~n path. In L~uu-.se to receipt of the channel reassignment acknowledgment signal, the AQ~;3 with respect to the packet data channel of any of the digital channels in the outgoing trAnP~;qsirn path rrntA;n;n~ the pad rhArACtPrQ is changed. The available packet data channel bandwidth ia thus increased or decreased by the num~ber of digital rhAnnPl Q added to or subtracted from the packet data channel without any need to interrupt data ~ Qsir~n or to reconfigure frame RAMs simultaneously in dif f erent nodes .
In acc:uL~ce with one aspect of the invention, the integer n is at least unity if the resulting packet data channel is itself used to transmit channel reassignment initiation or acknowle.ly signals. The integer n may be zero if channel reaasigDment in; t; At; r,n or acknowle ly signals are transmitted over any other DS0 channel or: in~t;r~n of DS0 channels.
2~771~1 ~ W0 95129570 For packet data channel bandwidth '"T Inci nn, prP~l~t~rm;nF~d pad rh~r~t~rs ignored by a remote or destination node are transmitted in any of the digital rh~nn~ in the Qllt~r,;nJ j ~cF2inn path not Acc 5 to the packet data channel in Le~ ae to detection of respective c_annel ~ ronn~rt reriuests. A channel reassignment ;n;t;~t;nn signal is t- 'ttPd to the remote node over the o~lt~o;ns ~1 ~cc;nn path and a channel rPA~ 3 acknowl~?'_ signal is received 10 from the remote node over the ;n~ 'n~ j - 'cc;on path.
In Le~ Sê to receipt of the channel r~A~;3 acknowledgment signal, any of the digital rh~nn~1 c in the outyoing i c8;nn path rnntA;n;n~ the pad rhAr~A~rt~rc are ~ignPcl to the packet data channel. The b;~n~1w;tlth 15 of the packet data channel is thus increased by the number of digital rhAnn~ added to the packet data channel without any need to interrupt data t ~; nn or to reconfigure frame RAMs simultaneously in different nodes. One or more digital channels may be added to an 20 existing packet data channel or a new packet data channel may be created in this manner.
For packet data channel bandwidth ~ esr~lon, predetermined pad rhAr~Ar~t~rs ignored by the remote node are transmitted in any of the digital channels in the 25 outgoing t - ~ j nn path A~s; ~n~d to the packet data channel in response to detection of respective channel connect reriuests. A channel reassignment ;n;t;At;rn signal is transmitted to the remote node over the outgoing trAn 'c~inn path and a channel reAc8j; ' 30 ~ signal is received from the remote node over the ; nl ~ n~ cinn path. In response to receipt of the channel r~cc;- acknowledgment signal, any of the digital rhAnn~ in the outgoing tr~n~ 'q8inn path rnntA;n;n~ the pad rhAr~A~t~r~ are 35 reassigned to rhAnn~l c other than the packet data channel . The hAnrlw; rlth of the packet data channel is thus decreased by the number of digital rhAnn~l ~
subtracted from the packet data channel without any need ~V095/29570 2 ~ 77 ~ 4 l to ; ntPrr~lrt data ~ ~ion or to reronf igure f rame RAMs simultaneously in different nodes. One or more digital channels may be #llhtr~rtPr1 from the packet data channel in this manner.
5 The digital rh~nnPl c a~y.. ~ u.. ously added to or asyllullrullously sllhtr~rtecl from a packet data channel may be individually switched voice rh~nnPlf~, may take the form of switched channels consisting of more than one digital channel each, may take the form of other packet 10 data channels, or may take the form of any ~ ;n~t;nn of the three. ~P~pPrt;ve channel reassignment initiation and channel rP~si; acknowledgment signals are typically transmitted over packet data channels in the respective outgoing and incoming I ~sil~n paths .
me invention may be more fully lln~lPr~tood from the following detailed description of a ~pPr;f;r --;
and its ~rPrAt;rm~ taken in the light of the ~c~ _ ying drawing and the ~ lJ~ P~ claims. For convenience, an asynchronously reconf igurable packet network node 20 embodying the invention i8 shown as having a tr;~nP~;tt;
portion and a receiving portion.
Brief r)P~criDtion of the Draw; n,g FIG. 1 is a block diagram of the transmitting portion of an a~y--ul.Lu~uusly reconfigurable packet 25 network node embodying the invention;
FIG. 2 is a block diagram of the receiving portion of an a~,y...;l.lu..uusly reconfigurable packet network node embodying the invention;
FIG. 3 lllustrates how the diagrams of FIGS. 1 and 2 fit together to form a block diagram of a lete packet network node embodying the invention;
FIG. 4 is a block diagram illustrating how source and dest; n~ t; rn packet network nodes embodying the invention work together;
FIG. 5 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;on packet network nodes embodying the invention prior to packet band PYr~n~ n;
~W095129570 ~l 7714~i 1 11. , FIG. 6 illustrates transmit and receive frames stored in frame RaMs in source and dest;nAt;nn packet network nodes embodying the invention during the f irst stage of packet band p~:lnQinn;
FIG. 7 illustrates transmit and receive frames - stored in frame RAr~s in source and dest;n~t;nn packet network nodes embodying the invention during the second stage of packet band PYI~nqinn;
FIG. 8 illustrates transmit and receive frames stored in frame RAMs in source and rlPqt;n~t;nn packet network nodes embodying the invention af ter packet band A n q i nn;
FIG . 9 illustrates transmit and receive f rames stored in frame R~Ms in source and dest;n~t;nn packet network nodes embodying the invention bef ore packet ~and c ~ ion;
FIG. 10 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;nn packet network nodes embodying the invention during the f irst stage of packet band ~ uion;
FIG. 11 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;nn packet network nodes embodying the invention during the second stage of packet band compression; and FIG. 12 illustrates transmit and receive frames stored in frame RAMq in source and dest;n~t;nn packet network nodes embodying the invention af ter packet band ion;
Detailed Descri~tion In FIG. 1, the transmitting portion 10 of an a~yl~c~Lulluusly reconfigurable packet network node embodying the invention; nrl 11~10~ a transmit multiplexer 12, a microprocessor 14, a packet band (PB~D) interface 16, a time division multiplex (TDM1) interface 18, a time division multiplex (TDM2) interface 20, a pad rh~ractPr (PAD) gPnPr~tnr 22, a top of frame ~PnPr~tor 24, a frame random access memory (RAM) 26, a synchronized frame pointer 28, and a repeatered outgoing digital W095129570 2177~41 '~
L 'Rsinn line 30. Sy~ l L~ ized frame pointer 28, which points to the next lor~tinn in a frame, advances during each time slot until the end of the frame i8 PnrOl~ntPred and then resynchronizes to the top of the frame. Additional packet or time division multiplex ;ntPrf~cPR to rh:~nnPl; ~Pcl service may be ;nrlll-lPtl, as ;n~l;r~tPd by a dashed line 19, between time division multiplex intPrf~rPR 18 and 20. Tnrll~rlPrl as portions of miuLuL~ruce~ or 14 are a channel reaSSigDment message gPnPr;~tnr (Channel Rp:~RR-igTl Message GPn~r~tor) 32 and a channel rP~RRi~ message ~lPte~tor (Channel Reassign Message Detector) 34. R~pe~tPred digital line 30 may, by way of example, take the form of a :,Lall.l~--l 24 channel T-1 Carrier digital ~ RR; nn line or its equivalent, where each of the 24 digital rh~nnPlR is tlPR;gn~tPd as a DS0 level channel.
The transmitting portion 10 in FIG. 1 of an a~y~ Lullously reconfigurable packet network node also ;nrl~ PR a null~ber of data paths 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, and 68, the L 'RRinn directions of which are ;n~9;C~tP~l by aL-~ ds. Data paths 36 and 38 couple packet network ;ntPrfAre 16 to transmit multiplexer 12 and mi.LuyLuC~s~or 14, respectively. Data paths 40 and 42 couple time division multiplex ;ntprf~re 18 to transmit multiplexer 12 and miuLu~LUce~or 14, respectively. Data paths 44 and 46 couple time division multiplex interface 20 to transmit multiplexer 12 and microprocessor 14, respectively. Data path 48 couples pad ~PnPr~tor 22 to transmit multiplexer 12. Data path 50 couples top of frame g~nPr~tnr 24 to transmit multiplexer 12.
Additionally in node transmitting portion 10, data path 52 couples frame RaM 26 to transmit multiplexer 12 and data path 54 couples synchronized frame pointer 28 to frame RaM 26. Data path 56 couples mi~;L~Lu~e~uI 14 to frame RaM 26 and data path 58 couples mi~;Lu~Luce~soL 58 to syll.hLunized frame pointer 28. Data path 60 couples channel rP:l~R;3 message generator 32 within ~W095/29570 2~7~14~ 0 mi~LU~LU~ UL 14 to packet network interface 16, data path 62 couples mi~;Lu~LucessùL 14 to pad gPnPr~tor 22, and data path 64 couples microprocessor 14 to top of ~rame generator 24. Pinally, data path 66 couples miulu~Luce:~3suL 14 to the receiving portion ~receiving portion 70 in FIG. 2) of the node and data path 68 couples the receiving portion of the node to channel reassignment message ~lPtectnr 34 within mi-;LU~LUCeS~UL
14 .
In FIG. 2, the receiving portion 70 of an a,iy~ Lulluuuly reconf igurable packet network node embodying the invention provides functions c ~ ry to those provided by i tting portion 10 in FIG.
and; nrl ll-lP~ a receive demultiplexer 72, a packet network 15 (PBND) ;ntPr~ ice 74, a time division multiplex (TDM1) interface 76, a time division multiplex (TDM2) interface 78, a frame RAM 80, a synchronized frame pointer 82, a top of frame r~y~ullLu~izer 84, a pad filter 86, and a repeatered ~n~ n~ digital i ,,q;nn line 88.
20 Additional packet or time divigion multiplex ;ntPr~
may be included, as ~n~l;r~ted by a dashed line 77, between time division multiplex interfaces 76 and 78.
Digital line 88 may, by way of example, take the form of a standard 24 channel T- 1 Carrier digital tr~n RRion 25 line, where each of the 24 digital channels is designated as a DS0 level channel.
Like its counterpart in transmitting portion 10 in FIG. 1, synchronized frame pointer 82 in receiving portion 70 points to the next lor~t;nn in a frame. Eere, 30 it first ~yll.:hLullizes itself with the top of frame ~n~;rP~t~nn received on the ;n~ nrJ data stream. Frame pointer 82 a.lv~ces during each time slot until the end of the frame is Pnro~lntPred and then resynchronizes to the top of the frame. Frame RAM 80 is addressed by 35 ~y~;llLullized frame pointer 82 and its output controls receive demultiplexer 72. Receive demultiplexer 72 accepts control from frame RAM ao and selects the appropriate dest;n~tinn for data. In the illustrated W095/29570 2 ~ 77 1 Q 1 c o~li of the invention, the data dest;nAtinn may be any of PBND interface 74, TDMl interface 76, TDM2 ;ntPrfAce 78, and top o~ frame ,iy..~llLu~lizer 84.
Like their counterparts in transmitting portion 10, TDM interfaces 76 and 78 are ;ntPrfPcP~ to rhAnnPl; 70d ~ervice, while PBND interface 74 ia an int~Prfpce to rArk.oti 7PCl data 8ervice. These interfaces provide cnnnPct;nn~ from receiving portion 10 to appropriate P-rt,,rn;ll environment. Top of frame synchronizer 84 controls ~yl~cllLul.ized frame pointer 82 and ~iPtPrm;nP~ if the receive frame is sy-nchronized with the incoming data stream. If it i8 not, top of frame synchronizer finds the top of f rame and f orces the f rame pointer into ~Iy~ L~ ;7~t;nn. Pad filter 86 recovers pad or intra packet fill rhArArtPr~ from the received data stream and removes them before P~ND intPrfAce 74 can perform any opPrAt;nn~ on them. In this way, the DS0 channels associated with packet data traf f ic that also contain these pad characters effectively do not exist as far as PBND ;ntPrfAce 74 is C ~ P~Pd. The effect i8 to allow uninterrupted packet data flow during the dy-namic packet bandwidth modif ication process, otherwise known as " breathing " .
Node receiving portion 70 in FIG. 2 also inrlll~iP~ a number of data t ~ inn paths 66, 68, 90, 92, 94, 96, 98, 100, 102, and 104, the tr~ ~inn directions of which are in~lirAtP~i by arrowheads. Data path 90 couples receive demultiplexer 72 to pad filter 86, and data path 92 couples pad filter 86 to packet band intPrfAre 74.
Data path 94 couples receive demultiplexer 72 to time division multiplex ;ntPrfAre 76, and data path 96 couples receive demultiplexer 72 to time division multiplex interface 78.
Additionally in the receiving portion 70, data path 98 couples frame RAM 80 to receive demultiplexer 72, data .
path 100 couples receive demultiplexer 72 to top of frame synchronizer 84, data path 102 couples top of frame synchronizer 84 to synchronized frame pointer 82, and ~ w0 95/2g570 2 1 7 7 1 4 1 data path 104 couples synchronized ~rame pointer 82 to frame RAM 80. Finally, data path 66 ~a c~nt;mlAt;on Of data path 66 in transmitting portion 10 in FIG. 1) is coupled from miuLu~ULucessoL 14 (in FIG. 1) to frame ~AM
5 ao, and data path 68 (a r~nt;nllAtir~n of data path 68 in transmitting portion 10 in FIG. 1) is coupled from packet band network interface 74 to channel rPA~ message rl~tert~lr 34 in mioLu~Luce~uL 14 (in FIG. 1).
FIG. 3 illustrates the manner in which FIGS. 1 and 2 10 are ~ ;nPd to form a complete asynchronously re~nfi~rAhle network node embodying the invention. As shown, FIG. 1 is placed 1 ~;AtPly above FIG. 2, with ~nnn~Dct; r1n~ between the two f igures consisting of data path~ 66 and 68.
FIG. 4 shows a complete packet data system 110 which ;nr~ P~ a source node 112, a dest;nAt;~n node 114, a data path 116 from source node 112 to dest;nAt;l~n node 114, and a data path 118 from destination node 118 to source node 112. Source node 112 and dest;nAt;nn node 114 are both asyn,_llru.luusly rec~nf; g--rAhl e packet network nodes embodying the invention and each; nrl llrlPF~ both a transmitting portion 10 (as shown in FIG. 1) and a receiving portion 70 ~as ghown in FIG . 2 ) . E ach of data paths 116 and 118 may, by way of example, take the form of a 1.544 megabit T-1 Carrier rPrPAtPred digital t ~si~n line, supporting 24 time division mult;r~YPd 64 kilobit DS0 rhAnnpl~
FIGS. 5 through 8 illustrate the ~nntPnt~ of frame RAM 26 in source node 112 and frame RAM 80 in degt;nAt;~n node 114, respectively, during s~r~ ive stages of packet band PYrAn~ion in A~C ., ~ e with the invention.
In FIG. 5, frame RAM 26 and frame RAM 80 store, for each of the 24 digital carrier rhAnnPl ~ (DS0 level) supported by a T-1 Carrier digital t ~;,n line, ;~Pnt;f;cAt;~n of the network ;nt~rfAcP, whether packet band or time division 1 t;rl PY, ~Acc~bq~l by that channel. The result, in each frame RAM, is a complete identif ication of the transmit f rame in source node 112 Wo9sns570 21 771 4 1 and the receive frame in dest;nAtinn node 114. Prior to packet band PYpAnAinn, the rnntPnt~ of both frame RAM 26 and frame RAM 80 are t~lPnt; rAl .
By way of illustration, system 110 in FIG. 4 begins with 8 DS0 rhRnnPl ~ A~ nP~l to a 512 kilobit per second packet band (PBND), 8 DS0 channels Aq~;~nPd to a first 512 kilobit per second time division multiplex band (TDM1), and 8 DS0 channels A~s;gnPd to a second 512 kilobit per second time division multiplex band (TDM2).
In practice, there may be more packet bands and more or fewer time division multiplex bands, and the packet bands _nd time division multiplex bands may contain more or ~ewer DS0 channels than shown in the example. As illustrated in FIG. 5, the initial channel lineups, prior to packet band expansion, include DS0 nhAnn~l~ 1, 4, 7, 10, 13, 16, 19, and 22 A~ nPd to TDM1, DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 assigned to TDM2, and DS0 channels 3, 6, 9, 12, 15, 18, 21, and 24 assigned to the packet band (PBND). For synchrnn;7At;nn purposes, both frame RAM 26 and frAme RAM 80 contain a top of fr_me (TOF) marker associated with DS0 channel 1. As illustrated, the channel lineups in both frame RAM 26 and ~rame RAM 80 are originally ;~lPnt;~Al FIG. 6 illustrates the channel lineups in fr_me RAMs 26 and 80 during the first stage of packet band expansion. A disconnect request has been received by time division multiplex ;nter~Ace 20 for each of DS0 ~hAnnP1~ 2, 5, 8, 11, 14, 17, 20, and 23 constituting TDM2 . In frame RAM 26, a pad or tl~ < y character PAD
has replaced the TDM2 designation for each of those newly available DS0 ~ hAnnPl ~. All channel assignments in frame RAM 80 remain the same as in FIG. 5. Dest;nA~;nn node 114 ignores all pad rhArArtPr~ PAD and a channel rPA~ ;n;t;2tinn signal is sent, by way of example, from source node 112 to ~lP~t;nAt;nn node 114 over packet band PBND. Alternatively, the channel rPA~is initiation signal may be sent over any other DS0 channel or nAt;nn of DS0 channels.
~ w095129570 21 77 t 4 1 I`l/L~
FIG . 7 illustrates the channel lineups in f rame RAMs 26 and 80 during the second stage of packet band P'rr~nqi''n- The pad rh~r~rtPrq PAD and the channel rP~qq;3 initiation signal have been received in 5 dest;n~t~nn node 114 but pad ~ilter 86 removes the pad characters PAD before they can be acted upon by PBND
interface 74. The channel lineup in frame RAM 26 remains the same as in FIG . 6, but the channel lineup in f rame RAM 80 has changed 80 that DS0 chlnnPlq 2, 5, 8, 11, 14, 17, 20, and 23 have been disrnnnPctPd from TDM2 and reassig~ed to packet band PBND. At the same time, a channel reassignment acknowls~, signal i8 sent, by way of example, in a packet band from dest;n~t;r~n node 114 to aource node 112 . ~1 t~rn~t~vely, the channel reassignment acknowledg signal may be sent over any other DS0 cha~nel or 'n:-t;r,n of DS0 rh~nnPlq Sixteen DS0 rh~nnPlq (2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, and 24) are now assigned to packet band PBND in f rame RAM 8 0 . In the ; , packet band 20 PBND has lost no bandwidth, there has been no ;ntPrr~rtion of packet traffic, and no ~y..,l.L.,~ized frame switch has been needed.
FIG. 8 illustrates the channel lineups in random access memories 26 and 80 after packet band PYr~nq;nn has been completed. The chamlel reassignment acknowl~
signal has now been received from dest;n~t;c~n node 114 by source node 112. As illustrated, the channel lineup in frame RAN 80 remains the same as in FIG. 7 and the channel lineup in frame RA~I 26 is the same as that in frame RAM 80. The pad or tllL~ ~ y rh~r~rtPrs PAD have been removed from DS0 rh5lnn"lq, 2, 5, 8, 11, 14, 17, 20, and 23 and those rhP~nnPl q have been reassigned to packet band PBND. I~ both source node 112 and dest;n~t;on node 114, packet band PBND now ncc-lr; Pq both the original packet band DS0 rh~nnPlq 3, 6, 9, 12, 15, 18, 21, and 25 and the dis~ ed TDM2 ch~nnPlq 2, 5, 8, 11, 14, 17, 20, and 23. At this point, packet band P13ND is using the Wogsl29s70 2~77t4~
full h~ntlw;rlth of both the DSO Channel8 of the nr;~;nAl packet band and the original TDM2 DS0 rh~nnPl ~.
FIGS . 9 through 12 illustrate the contents of f rame RAM 26 in source node 112 and frame RAM 80 in de8tinAt;rn 5 node 114, respectively, during surrP~ive stages of packet band, ~ lon in Arrortl~nre with the invention.
In FIG. 9, frame RAM 26 and frame R~M 80 store, for each of the 24 digital carrier channels (DS0 level) supported by a T- 1 Carrier digital i ~ n line, 10 ;~iPnt;fication of the network ;ntPrfAce, whether packet band or time division multiplex, accessed by that channel. The result, in each frame RAM, is once again a complete ;~iPnt;f~cation of the transmit frame in source node 112 and the receive frame in dest;nAt;nn node 114.
15 Prior to packet band compression, the contents of both frame ~AM 26 and frame RAM 80 are originally ;tiPnt;r2l.
By way of ~urther illustration, system 110 in FIG. 4 begins with 16 DS0 rhAnnPl ~: A~si ~nP~l to a 1024 kilobit per second packet band ~PBND) and 8 DS0 channels assigned 20 to a first 512 kilobit per second time division multiplex band (TDM1). In rr~r~tirP, there may be more packet bands and more or fewer time division multiplex bands, and the packet bands and time division multiplex bands may contain more or fewer rh~nnF~l ~ than shown in the example.
25 As illustrated in FIG. 9, the initial channel lineups, prior to packet band: ~ ~s~3ion, include DS0 channels 1, 4, 7, 10, 13, 16, 19, and 22 assigned to TDM1 and DS0 channels 2, 3, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, and 24 ~ ; gnPd to the packet band (PBI~D) . For 30 synchr--n; 7Ati~n purposes, both frame RAM 26 and frame RAM
80 contain a top of frame (TOF) marker A~or;AtPd with DS0 channel 1. As illustrated, the channel lineups in both frame RAM 26 and frame RAM 80 are ;~lPnt;rAl.
FIG. 10 illustrates the channel lineups in frame 35 RAMs 26 and 80 during the f lrst stage of packet band compression. A connect re~auest has been received by time division multiplex interface 20 for each of DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 constituting TDM2. In 2 ~ 77 t 4 1 ~rame RAM 26, a pad or throw away rh~r~tPr PAD has replaced the PBND ~3P~; gnAt1 r,n ~or each of those no longer available DS0 rh~nnPl ~ . All channel assignments in frame RAM 60 remain the same as in FIG. 9. Dest;n~t;rn node 114 ignores all pad rh~r~rtPr~ PAD and a channel - reassignment initiation signal is sent, by way of example, from source node 112 to dest;n~t;rln node 114 over packet band PBND. Alternatively, the channel reassignment initiation signal may be sent over any other DS0 channel or ;n~t;r,n of DS0 rh;-nnPl~.
FIG. 11 illustrates the channel lineups in frame RAMs 26 and 80 during the second stage of packet band ~ e.-~lon. The pad rh~r~rtpr~ PAD and the channel reassignment signal have been received in des~;nAt;r~n node 114 but pad filter 86 removes the pad rh~r~r~tPr~ PAD
before they can be acted upon by PBND interface 74. The channel lineup in frame RAM 26 remains the same as in FIG. 6, but the channel lineup in frame RAM 80 has changed 80 that DS0 channels 2, 5, 8, 11, 14, 17, 20, and 20 23 have been rl;~rrnnPctPrl from packet band PBND and rP ~ nPrl to TDM2. At the same time, a channel reassignment acknowledy signal is sent, by way of example, in a packet band from dest;n~t;on node 114 to source node 112. Alternatively, the channel rP~
25 acknowledgemeIlt signal may be sent over any other DS0 channel or 'n:-t;rn of DS0 rh~nnPlQ. In frame RAM 80, DS0 rh~nnPl~ 1, 4, 7, 10, 13, 16, 19, and 22 are assigned to TDMl, DS0 rh~nnPl ~ 2, 5, 8, 11, 14, 17, 20, and 23 are assigned to TDM2, and DS0 rh~nnPl~ 3, 6, 9, 12, 15, 18, 30 21, and 24 are ~signP~l to packet band PBND ln frame RAM
80. In the --~ ; , packet band PBND has c~nt;m~Pd to operate at a 512 kilobit per second bit rate (its bit - rate after, _ es~ion), there has been no interruption of packet traffic, and no synchronized frame switch has 3 5 been needed .
FIG. 12 ;llll~tr~tP~ the channel lineups in frame RAMs 26 and 80 after pack band ~ ession has been completed. The channel reaggignment acknowl ~ ~
W095129570 2 ~ 7 7 ~ 4 ~
aignal haa been received from dest;n~t;nn node 114 by source node 112. As illustrated, the charmel lineup in frame RAM 80 remains the same aa in FIG. 11 and the channel lineup in frame RAM 26 is the same as that in frame RAM 80. The pad or throw away nh~r~ct~r~ PAD have been removed from DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 and thoae rh~nn~-l q have been reasaigned to TDM2.
In both source node 112 and deattn~t~nn node 114, packet band PBND now occupies only DS0 nh~nn~ 3, 6, 9, 12, 15, 18, 21, and 24 and TDM2 now occupiea DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23. Packet band PBND, TDM1, and TDM2 are now all operating at 512 kilobit per aecond bit rates .
Two ~ of actual data streams tranamitted in a packet band from aource node 112 to dest;n~t;nn node 114 during aucc~a~; ve packet band f'Yp~n~i nn and packet band ~a~ion are illuatrated in TABLES 1 and 2 below.
EXAMPLE OF SINGLE C~ANNEL PACRET BAND RYP~ ~ AND
DATA: 24,12,15,62,5A,75,10,27,40 n~ OUT
~5L ~3E~ 8 INACT 8 ADDED 9 ~rTIVE 9 D~OPPED
ESC~5A
REPLACE 5A WITEI 5A, 7A (SEND PBAIN TEXT 5A AS 5A, 7A) REPLACE 24 WITEI 5A, 64 (SEND PI,AIN TEXT 24 AS 5A, 64) ~1 7~ 4 1 ~ WO 95,29570 ~ ........
TA3~iE 1 illustrate~ the manner in which the invention permits a~yllo1lLu.luus packet band PYp~n~inn and e~Dion ~rom the gt:lntlrn;nt of rh~r~rtPr~ actually transmitted ~rom source node 112 to dest;n~t;nn node 114.
5 In this example PYp~n~inn and es,iion both involve only single DS0 rh~nnPl ~. As shown, it is assumed, by way of example, that the data actually being transmitted over the packet band channel consist o~ a sPrl~Pnt;~1 rh~ractPr stream 24,12,1s,62,sA,7s,10,27,40... An actual 10 data stream will contain many additional rh~r~rtPrq, but these will suffice for illustration purposes. It is assumed that the packet band, before P~r~n~inn, consists of DS0 rh~nnPl~ 1, 2, 5, 7, 9, 15, 16, and 17 and that DS0 channel 8 is assigned to a time division multiplex 15 channel. It i8 further assumed, by way o~ example, that 5A is tlP~ign~tP~l as an escape character and that 24 is designated as the pad rh~r~CtPr. To send a plain text 5A, by way of example, the rh~r~rtPr~ actually sent are 5A,7A and to send a plain text 24, by way of example, the 20 rh~ractPr~ actually sent are 5A, 64. For ease of illustration, each column begins with the same sequence o~ data rh~r~rtPr~. In practice, each column would begin with whatever data rh~r?ctpr was being transmitted when the tr;ln~:;t;nn to the status le~Lese~ed by the column 2 5 began .
The first column (DS0) in TAi3I,E 1 irlPnt;~;Pq the DS0 rh;lnnPl~ with Which the example is c~ rPI"Pd. Before packet band PYr~n~inn, the characters shown in the second column (BEFORE) are transmitted in the; n~; r~ted packet 30 band DS0 rh~nnPl ~. DS0 channel 8 is shown blank in the second column because at this stage it is not carrying packet band infnrr-t;on. Note that, because 24 has been Leselved to Le~lése~t the pad rh~r?rtpr~ it has been replaced in the second column by the sP~rlPnre 5A, 64 and 35 that, because 5A has been leselved to represent an escape rh~r~ctPr~ it ha8 been replaced in the second column by the serlllPnre 5A, 7A.
wo95n9s7o 2 ~ 7 7 1 4 1 I_1/L_ ~
me third colum~ ( 8 INACT) in TA3LE 1 shows what happens when DS0 cha~nel 8 goes inactive in L~ ullse to a disconnect request. The pad rh ~r~rt~r 24, which destin~t;r,n node 114 has been yL."_ ' to ignore or discard, is transmitted in DSO channel 8. Pad rh~rPct~r 24 has been it:~l;r~ fl in TABLE 1 for: _h~
me fourth column (8 ADD3D) in TAB3~E 1 shows what happens after DS0 channel 8 has been added to the packet band. Packet band data rh~r~rt~r~ are now tra~smitted in 10 se~l~nre in the respective packet band DSO channels.
me fifth columrl (9 ACTIVE) in TABIE 1 shows what happeIls af ter DS0 channel 9 is about to be preempted by a time division multiplex channel in L_~i~Ull3C to a connect request. Pad rh~r~t~r 24 is transmitted in DS0 channel 15 9 and the packet band data stream is cnnfin~fl to DSO
channels l, 2, 5, 7, 8, 15, 16, and 17.
The sixth column (9 DROPPED) in TABLE 1 shows what happen~ after DS0 channel has been dropped from the packet band channel. The packet band data stream is 20 rr,nf;nPfl to DS0 rh~nn~l~ 1, 2, 5, 7, 8, 15, 16, and 17.
W095129570 2 1 77 ~ 4 ~
BXAMPLE OF PACRET BAND ~ L .~ Sl~
DATA: 24,12,15,62,5A,75,10,27,40 n~T~ OU~ ~
8,10,11 8,10,11 15,16 15,16 ~Q ~ INACT ~= ~E DROPP3D
8 j~ 62 62 62 2~ 7A 7A 7A
1515 5A 5A 10 j~
ESC~5A
PAD~24 20REPLACE 5A WITH 5A, 7A (SEND PIAIN TEXT 5A AS 5A, 7A) REPLACE 24 WITH 5A, 64 (SEND PI,AIN TEXT 24 AS 5A, 64) TABLE 2 further illustrates the manner in which the invention permits a.iy.lcll~ull.,us packet band PYrAn~inn and , _ ession from the stAn~lro;nt of r~hAr~rtpr~ actually transmitted from source node 112 to dest;n~t;on node 114.
In this example PYr~nqir~n and ~ ession both involve multiple DSO rh~nnPl ~ . As shown, it is again assumed, by way of example, that the data actually being transmitted over the packet band channel con8i8t of the 8PqllPnt; Al character stream 24 ,12 ,15, 62, 5A, 75 ,1 0, 2 7, 4 0 . . . An actual data stream will contain many additional -hArArtPrA, but these will suffice for illustration ~uL~08e8. It is again assumed that the packet band, bef ore PYr~n~ n, consists of DSO rhAnnPl~ 1, 2, 5, 7, 9, 15, 16, and 17.
This time, it is assumed that DSO rhAnnPl~ 8, 10, and 11 are assigned to one or more time division multiplex ~ h:lnnPl ~ . It ig again further assumed, by way of w09s/2gs70 2177~4t ~ o o example, that 5A is designated as an escape rhArArtPr and that 24 is ~lP~ign~ted as the pad rhArACtPr. To send a plain text 5A, by way of ex_mple, the rhAr~ACtPrR actually sent are 5A,7A and to send a plain text 24, by way o~
5 example, the rhArArtprs actually sent are 5A, 64. For ease of illustration once more, each column begins with the same ae~lpn~e of data rhAr~ActPrR. In rrA~-t~ce, each column would begin with whatever data rhAractPr was being transmitted when the transition to the status represented 10 by the column began.
The first column (DS0) in TABLB 2 j~lPnt~fiPR the DS0 channels with which the exAmple is rnnrPrnP~. Before packet band PYrAnR~-7n, the characters shown in the second column ~BEFORE) are transmitted in the ~n~l~r~tPd packet band DS0 channelR. DS0 channels 8, 10, and 11 are shown b~Lank in the second column because at this stage they are not carrying packet band infnr~--tinn. Note that, because 24 haR been LeseLved to le~LesellL the pad rhArRctPr, it has been replaced in the second column by the sP~I~nre 5A,64 and that, because 5A has been reserved to LeyLesellL
an escape rhAr~CtPr, it has been replaced in the second column by the 8PrltlPnr~ 5A, 7A.
The third column ( 8 ,10 ,11 INACT) in TA~LE 2 shows what happens when DS0 channels 8, 10, and 11 go inactive in response to disconnect requests. The pad ~hArActPr 24, which dest;nAt1nn node 114 has been ~ u' ' to ignore or discard, is transmitted in DS0 channels 8, 10, and 11. Pad rh~r~rtPr 24 has been italicized in TABLE 2 for --R~ R, .
The fourth column (8,10,11 ADDED) in TAB~E 2 shows what happens after DS0 channels 8, 10, and 11 have been added to the packet band. Packet band data rh;~rArterR
are now transmitted in 8etrl~nre in the respective packet band DS0 rhAnnpl R .
The fifth column (15,16 ACTnrE) in TAB~E 2 shows what happens af ter DS0 channels 15 and 16 are about to be preempted by a time division multiplex channel in le~ e to connect requests. Pad rhAr~rtPr 24 is ~ W0 95129570 2 1 7 7 t ~
t~:~n~--~ ttPd in DS0 ~h~nnPl ~ 15 and 16 aI~d the packet ba~d data stream i8 cr-nfinPcl to DS0 rh~nnPl~ 1, 2, 5, 7, 8, 9, 10, 11, and 17.
The ~ixth column (15,16 DROPPED) in TABLE 1 shows 5 what happen~ after DS0 rh~nnPl ~ 15 and 16 have been dropped from the packet barld chaImel. The packet band data ~tream i~ c~nfinpd to DS0 ~-h~nnPl ~ 1, 2, 5, 7, 8, 9, 10, 11, and 17.
p~rT~T~T nl~T~ ~RD~ MT.q.qIn~ WITH ~q~T~ TTq T~DWTnTI~ SWIT-'tTT~
Fi~1 ,i of th~ Tnvf~nt i nn This invention relates generally to packet data 5 trAn~ a; on systems and, more particularly, to packet data i aa; nn systems in which bAn~lw~ th i9 switched between packet i qai nn rhAnnc~l q and other t a~;nn rhAnn.~la which may themselves be voice L 'aainn rhAnn~la, L aainn channels in the form of multiple voice trAnr~;aainn rhAnn~lq, or additional packet data L alqinn rhAnn~l q.
T~AI l,~l "ll~l of th-~ Tnv.--nt;nn In modern day digital tPl:- ications~ the b~rkhnno for a packet data network is typically a T-1 15 Carrier digital i qa; nn line or its equivalent . A
T-1 Carrier digital L - as;on line opF~r:~tPa at a bit rate of l . 544 megabits per second, providing a total b~nrlW;~th of 1.544 M~Iz, and normally gupports 24 time division mult;rl-~Y~l digital DS0 rh~nn~la. Bach of these 24 digital DS0 rh~nn~l a has an effective bit rate of 64 kilobits per second, providing a hAnrlw; dth of 64 K~z each. A typical packet network; nrl l~d~q a plurality of s~rAr~te packet network nodes, coupled to one another by T- 1 Carrier digital ~_ ~ainn lines or their Z5 equivalent.
A packet network node generally opPr~t~a to assign a plurality of T-1 digital DS0 rh~nn~l a to form a hroader band packet data L a,ainn channel, leaving the L~ ~n;ng digital channels to be used either by additional packet data L_ ' aainn rh~nn~l a or as such s~p~rAte and distinct time division multiplex circuit switched rhAnnP1 a as voice or channels in the form of multiple voice rh~nn~l a. Becau_e such additional time division multiplex rh~nn~la as _Pr~r~tl~ voice channels or rh~nn~la formed by multiple voice channels may sometimes be inactive, it can be useful to make their unused bandwidth available temporarily to increase the bandwidths available to active packet data ~ qf~inn rhAnnf~ln In the pa5t, ~uch t~ r;ly unu8ed bandwidth has been r~Al 1 ocAted either ~Iy~ullLu-lOuuly or auy ~ 11L U~ ~uugly .
In syn.:llLul,uus r~llor~t;nn, frame random access ~ (often called, more simply, frame RAMs) rnntA~n;n~ digital channel allocation infnrr-t;nn in packet network nodes at both ends of a T- 1 Carrier tr~nP~ 3;nn line need to be reconfigured 8; ltAn~ollcly in order to ensure cnnt;m~o~lq flow of data. In such aLL~. ' q, a second frame is typically developed with all changes incorporated within it at both source and dest~nAtinn nodes before a signal from the source node to the dest~nAt;nn node sper;f;~q when to change the frame.
Synch~ulluu~i reconfiguration tends to be highly complex and ~ -~1n~ of memory, part;rlllRrly when more than one packet channel is involved.
Past asynchronous reconfiguration terhn;r~ require that ;nt~rnr~ l packet data t~--- q8;nn be ;ntorrllrt~l each time a frame RAM reconfirJurAtinn at opposite ends of the t 'qqjnn 8y8tem take8 place. Typically, packet data buf f ering is re~uired each time the f rame is reconf igured. Such asynchronous bandwidth switching also becomes an increasingly complex procegs a8 Afl~l;t;nnAl digital rh~nn~l A are reallocated, particularly if more than one packet channel is involved.
S ry of the Jnvention The invention permits bandwidth in a packet data trAnr--; ~qinn system to be switched asynchronously without interruption of data trAnn~;qq;on and with a minimum of 30 circuit complexity. In particular, a packet channel is permitted to "breathe~, gaining bandwidth when Aflrl;t;nnAl bandwidth becomes available from other t~ ~ r;ly un:u8ed digital rhAnnPl q and losing such additional bandwidth when such digital rhAnn~l q revert to other use. Frame 35 RA~s in packet network nodes at both ends of a T-l Carrier digital L ' ~:,q,; nn line no longer need to be reconf igured simultaneously . To permit such uninterrupted a~yl~ullLulluu8 op~rAt;nn, a ~pad~ or "throw ~ wo95ngs70 2 l 7 71 ~
awayn rh ~r;3ctPr i5 de~ined which i8 ignored or discarded whenever it is received by one packet network node f rom another. Such a "pad" or "tllL~ ~" character is unique in the sense that it is distinct from and may not be 5 ~ r ,~ 1 with rh~rærtPr~ or bytes which may occur in normal data ~_ ~8; nn 8~Ue:L~Ce8 .
The invention ~ v~:r~ - problems PnrollntPrPrl in the past by permitting packet traffic to rnnt;nllP flowing as h::lnrlw;~lth reconfiguration or gwitching takes place.
lO Packet data rnnt;nllP to propagate at a rate consistent with the smaller of either the previous or the next packet band conf iguration while bandwidth switching occurs . The rate at which packet data f low during bandwidth switching is, in other words, either the rate 15 ; ' ~tPly prior to or the rate; ''AtPly after bandwidth switching, tlPr~nr9;n~ upon which configuration allows f or le~s packet bandwidth . ;3andwidth switching may be completed in as little as a single frame and each reconfiguration is controlled by ;r~tion between 20 packet nodes, thus Pl ;m;n;~t;n~ any need for Pl~horlte frame synchronization methods.
The invention, f rom one ; ~ LdllL aspect, takes the form of an asyn~ u~ly reconfigurable packet network node having a transmitting portion f or transmitting 25 digital message data to another remote packet network node over an out~;n~ digital tr~n^~~;nn path and a receiving portion ~or receiving digital message data from the remote node over an ;nl n~ digital tr:~r- '~ginn path. Each of the digital tr~nF~ i nn paths employed 30 with such a reconfigurable packet node consists of a predetermined number of time division multiplexed digital rh~nnPlR Each of the time division mult;r1PYP~l digital rh~nnPl ~ has active and inactive states r9PtPrm;nPd by respective digital channel connect and ~; ~cnnn-~ct 35 re~uests. In standard tele r~t;nn~ tprm;nnl~gyl a connect request causes a channel to shi~t from an inactive state to an active state, while a ~ ronnPct W0 95129570 2 ~ 7 ~
request causes a channel to shif t f rom an active state to an inactive state.
From another important aspect, the invention takes the f orm of a method of operA t; n~ one or more such asynchronously reconf igurable packet network nodes .
In an a~y~ u~ ~uusly reconf igurable packet network node constructed or opPrAtPrl in Arcr~rflAnre with the invention, n of the digital channels in the outgoing L QQ~ on path are A~5i~nPd to a packet data channel, where n is an integer equal to or greater than zero, and connect and rl; QCr~nnPCt requests are ~lPtected to signal shifts of any of the digital rhAnnPl Q in the outgoing ~ 'qQ;nn path between respective active and inactive states. PrP~lPtPrm;nPd pad rhArAotprs ignored by a remote or dest;nAt;rn node are transmitted in any of the digital channels in the outgoing t---- QQirn path in L~ff~uuse to ~lPtect;on of respective connect or disconnect requests.
A channel rPAQsi_ initiation signal is transmitted to the remote node over the outgoing t---- ' QQ; on path and a channel rPA~QiS acknowledgment signal is received f rom the remote node over the incoming t ' Qsir~n path. In L~uu-.se to receipt of the channel reassignment acknowledgment signal, the AQ~;3 with respect to the packet data channel of any of the digital channels in the outgoing trAnP~;qsirn path rrntA;n;n~ the pad rhArACtPrQ is changed. The available packet data channel bandwidth ia thus increased or decreased by the num~ber of digital rhAnnPl Q added to or subtracted from the packet data channel without any need to interrupt data ~ Qsir~n or to reconfigure frame RAMs simultaneously in dif f erent nodes .
In acc:uL~ce with one aspect of the invention, the integer n is at least unity if the resulting packet data channel is itself used to transmit channel reassignment initiation or acknowle.ly signals. The integer n may be zero if channel reaasigDment in; t; At; r,n or acknowle ly signals are transmitted over any other DS0 channel or: in~t;r~n of DS0 channels.
2~771~1 ~ W0 95129570 For packet data channel bandwidth '"T Inci nn, prP~l~t~rm;nF~d pad rh~r~t~rs ignored by a remote or destination node are transmitted in any of the digital rh~nn~ in the Qllt~r,;nJ j ~cF2inn path not Acc 5 to the packet data channel in Le~ ae to detection of respective c_annel ~ ronn~rt reriuests. A channel reassignment ;n;t;~t;nn signal is t- 'ttPd to the remote node over the o~lt~o;ns ~1 ~cc;nn path and a channel rPA~ 3 acknowl~?'_ signal is received 10 from the remote node over the ;n~ 'n~ j - 'cc;on path.
In Le~ Sê to receipt of the channel r~A~;3 acknowledgment signal, any of the digital rh~nn~1 c in the outyoing i c8;nn path rnntA;n;n~ the pad rhAr~A~rt~rc are ~ignPcl to the packet data channel. The b;~n~1w;tlth 15 of the packet data channel is thus increased by the number of digital rhAnn~ added to the packet data channel without any need to interrupt data t ~; nn or to reconfigure frame RAMs simultaneously in different nodes. One or more digital channels may be added to an 20 existing packet data channel or a new packet data channel may be created in this manner.
For packet data channel bandwidth ~ esr~lon, predetermined pad rhAr~Ar~t~rs ignored by the remote node are transmitted in any of the digital channels in the 25 outgoing t - ~ j nn path A~s; ~n~d to the packet data channel in response to detection of respective channel connect reriuests. A channel reassignment ;n;t;At;rn signal is transmitted to the remote node over the outgoing trAn 'c~inn path and a channel reAc8j; ' 30 ~ signal is received from the remote node over the ; nl ~ n~ cinn path. In response to receipt of the channel r~cc;- acknowledgment signal, any of the digital rhAnn~ in the outgoing tr~n~ 'q8inn path rnntA;n;n~ the pad rhAr~A~t~r~ are 35 reassigned to rhAnn~l c other than the packet data channel . The hAnrlw; rlth of the packet data channel is thus decreased by the number of digital rhAnn~l ~
subtracted from the packet data channel without any need ~V095/29570 2 ~ 77 ~ 4 l to ; ntPrr~lrt data ~ ~ion or to reronf igure f rame RAMs simultaneously in different nodes. One or more digital channels may be #llhtr~rtPr1 from the packet data channel in this manner.
5 The digital rh~nnPl c a~y.. ~ u.. ously added to or asyllullrullously sllhtr~rtecl from a packet data channel may be individually switched voice rh~nnPlf~, may take the form of switched channels consisting of more than one digital channel each, may take the form of other packet 10 data channels, or may take the form of any ~ ;n~t;nn of the three. ~P~pPrt;ve channel reassignment initiation and channel rP~si; acknowledgment signals are typically transmitted over packet data channels in the respective outgoing and incoming I ~sil~n paths .
me invention may be more fully lln~lPr~tood from the following detailed description of a ~pPr;f;r --;
and its ~rPrAt;rm~ taken in the light of the ~c~ _ ying drawing and the ~ lJ~ P~ claims. For convenience, an asynchronously reconf igurable packet network node 20 embodying the invention i8 shown as having a tr;~nP~;tt;
portion and a receiving portion.
Brief r)P~criDtion of the Draw; n,g FIG. 1 is a block diagram of the transmitting portion of an a~y--ul.Lu~uusly reconfigurable packet 25 network node embodying the invention;
FIG. 2 is a block diagram of the receiving portion of an a~,y...;l.lu..uusly reconfigurable packet network node embodying the invention;
FIG. 3 lllustrates how the diagrams of FIGS. 1 and 2 fit together to form a block diagram of a lete packet network node embodying the invention;
FIG. 4 is a block diagram illustrating how source and dest; n~ t; rn packet network nodes embodying the invention work together;
FIG. 5 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;on packet network nodes embodying the invention prior to packet band PYr~n~ n;
~W095129570 ~l 7714~i 1 11. , FIG. 6 illustrates transmit and receive frames stored in frame RaMs in source and dest;nAt;nn packet network nodes embodying the invention during the f irst stage of packet band p~:lnQinn;
FIG. 7 illustrates transmit and receive frames - stored in frame RAr~s in source and dest;n~t;nn packet network nodes embodying the invention during the second stage of packet band PYI~nqinn;
FIG. 8 illustrates transmit and receive frames stored in frame RAMs in source and rlPqt;n~t;nn packet network nodes embodying the invention af ter packet band A n q i nn;
FIG . 9 illustrates transmit and receive f rames stored in frame R~Ms in source and dest;n~t;nn packet network nodes embodying the invention bef ore packet ~and c ~ ion;
FIG. 10 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;nn packet network nodes embodying the invention during the f irst stage of packet band ~ uion;
FIG. 11 illustrates transmit and receive frames stored in frame RAMs in source and dest;n~t;nn packet network nodes embodying the invention during the second stage of packet band compression; and FIG. 12 illustrates transmit and receive frames stored in frame RAMq in source and dest;n~t;nn packet network nodes embodying the invention af ter packet band ion;
Detailed Descri~tion In FIG. 1, the transmitting portion 10 of an a~yl~c~Lulluusly reconfigurable packet network node embodying the invention; nrl 11~10~ a transmit multiplexer 12, a microprocessor 14, a packet band (PB~D) interface 16, a time division multiplex (TDM1) interface 18, a time division multiplex (TDM2) interface 20, a pad rh~ractPr (PAD) gPnPr~tnr 22, a top of frame ~PnPr~tor 24, a frame random access memory (RAM) 26, a synchronized frame pointer 28, and a repeatered outgoing digital W095129570 2177~41 '~
L 'Rsinn line 30. Sy~ l L~ ized frame pointer 28, which points to the next lor~tinn in a frame, advances during each time slot until the end of the frame i8 PnrOl~ntPred and then resynchronizes to the top of the frame. Additional packet or time division multiplex ;ntPrf~cPR to rh:~nnPl; ~Pcl service may be ;nrlll-lPtl, as ;n~l;r~tPd by a dashed line 19, between time division multiplex intPrf~rPR 18 and 20. Tnrll~rlPrl as portions of miuLuL~ruce~ or 14 are a channel reaSSigDment message gPnPr;~tnr (Channel Rp:~RR-igTl Message GPn~r~tor) 32 and a channel rP~RRi~ message ~lPte~tor (Channel Reassign Message Detector) 34. R~pe~tPred digital line 30 may, by way of example, take the form of a :,Lall.l~--l 24 channel T-1 Carrier digital ~ RR; nn line or its equivalent, where each of the 24 digital rh~nnPlR is tlPR;gn~tPd as a DS0 level channel.
The transmitting portion 10 in FIG. 1 of an a~y~ Lullously reconfigurable packet network node also ;nrl~ PR a null~ber of data paths 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, and 68, the L 'RRinn directions of which are ;n~9;C~tP~l by aL-~ ds. Data paths 36 and 38 couple packet network ;ntPrfAre 16 to transmit multiplexer 12 and mi.LuyLuC~s~or 14, respectively. Data paths 40 and 42 couple time division multiplex ;ntprf~re 18 to transmit multiplexer 12 and miuLu~LUce~or 14, respectively. Data paths 44 and 46 couple time division multiplex interface 20 to transmit multiplexer 12 and microprocessor 14, respectively. Data path 48 couples pad ~PnPr~tor 22 to transmit multiplexer 12. Data path 50 couples top of frame g~nPr~tnr 24 to transmit multiplexer 12.
Additionally in node transmitting portion 10, data path 52 couples frame RaM 26 to transmit multiplexer 12 and data path 54 couples synchronized frame pointer 28 to frame RaM 26. Data path 56 couples mi~;L~Lu~e~uI 14 to frame RaM 26 and data path 58 couples mi~;Lu~Luce~soL 58 to syll.hLunized frame pointer 28. Data path 60 couples channel rP:l~R;3 message generator 32 within ~W095/29570 2~7~14~ 0 mi~LU~LU~ UL 14 to packet network interface 16, data path 62 couples mi~;Lu~LucessùL 14 to pad gPnPr~tor 22, and data path 64 couples microprocessor 14 to top of ~rame generator 24. Pinally, data path 66 couples miulu~Luce:~3suL 14 to the receiving portion ~receiving portion 70 in FIG. 2) of the node and data path 68 couples the receiving portion of the node to channel reassignment message ~lPtectnr 34 within mi-;LU~LUCeS~UL
14 .
In FIG. 2, the receiving portion 70 of an a,iy~ Lulluuuly reconf igurable packet network node embodying the invention provides functions c ~ ry to those provided by i tting portion 10 in FIG.
and; nrl ll-lP~ a receive demultiplexer 72, a packet network 15 (PBND) ;ntPr~ ice 74, a time division multiplex (TDM1) interface 76, a time division multiplex (TDM2) interface 78, a frame RAM 80, a synchronized frame pointer 82, a top of frame r~y~ullLu~izer 84, a pad filter 86, and a repeatered ~n~ n~ digital i ,,q;nn line 88.
20 Additional packet or time divigion multiplex ;ntPr~
may be included, as ~n~l;r~ted by a dashed line 77, between time division multiplex interfaces 76 and 78.
Digital line 88 may, by way of example, take the form of a standard 24 channel T- 1 Carrier digital tr~n RRion 25 line, where each of the 24 digital channels is designated as a DS0 level channel.
Like its counterpart in transmitting portion 10 in FIG. 1, synchronized frame pointer 82 in receiving portion 70 points to the next lor~t;nn in a frame. Eere, 30 it first ~yll.:hLullizes itself with the top of frame ~n~;rP~t~nn received on the ;n~ nrJ data stream. Frame pointer 82 a.lv~ces during each time slot until the end of the frame is Pnro~lntPred and then resynchronizes to the top of the frame. Frame RAM 80 is addressed by 35 ~y~;llLullized frame pointer 82 and its output controls receive demultiplexer 72. Receive demultiplexer 72 accepts control from frame RAM ao and selects the appropriate dest;n~tinn for data. In the illustrated W095/29570 2 ~ 77 1 Q 1 c o~li of the invention, the data dest;nAtinn may be any of PBND interface 74, TDMl interface 76, TDM2 ;ntPrfAce 78, and top o~ frame ,iy..~llLu~lizer 84.
Like their counterparts in transmitting portion 10, TDM interfaces 76 and 78 are ;ntPrfPcP~ to rhAnnPl; 70d ~ervice, while PBND interface 74 ia an int~Prfpce to rArk.oti 7PCl data 8ervice. These interfaces provide cnnnPct;nn~ from receiving portion 10 to appropriate P-rt,,rn;ll environment. Top of frame synchronizer 84 controls ~yl~cllLul.ized frame pointer 82 and ~iPtPrm;nP~ if the receive frame is sy-nchronized with the incoming data stream. If it i8 not, top of frame synchronizer finds the top of f rame and f orces the f rame pointer into ~Iy~ L~ ;7~t;nn. Pad filter 86 recovers pad or intra packet fill rhArArtPr~ from the received data stream and removes them before P~ND intPrfAce 74 can perform any opPrAt;nn~ on them. In this way, the DS0 channels associated with packet data traf f ic that also contain these pad characters effectively do not exist as far as PBND ;ntPrfAce 74 is C ~ P~Pd. The effect i8 to allow uninterrupted packet data flow during the dy-namic packet bandwidth modif ication process, otherwise known as " breathing " .
Node receiving portion 70 in FIG. 2 also inrlll~iP~ a number of data t ~ inn paths 66, 68, 90, 92, 94, 96, 98, 100, 102, and 104, the tr~ ~inn directions of which are in~lirAtP~i by arrowheads. Data path 90 couples receive demultiplexer 72 to pad filter 86, and data path 92 couples pad filter 86 to packet band intPrfAre 74.
Data path 94 couples receive demultiplexer 72 to time division multiplex ;ntPrfAre 76, and data path 96 couples receive demultiplexer 72 to time division multiplex interface 78.
Additionally in the receiving portion 70, data path 98 couples frame RAM 80 to receive demultiplexer 72, data .
path 100 couples receive demultiplexer 72 to top of frame synchronizer 84, data path 102 couples top of frame synchronizer 84 to synchronized frame pointer 82, and ~ w0 95/2g570 2 1 7 7 1 4 1 data path 104 couples synchronized ~rame pointer 82 to frame RAM 80. Finally, data path 66 ~a c~nt;mlAt;on Of data path 66 in transmitting portion 10 in FIG. 1) is coupled from miuLu~ULucessoL 14 (in FIG. 1) to frame ~AM
5 ao, and data path 68 (a r~nt;nllAtir~n of data path 68 in transmitting portion 10 in FIG. 1) is coupled from packet band network interface 74 to channel rPA~ message rl~tert~lr 34 in mioLu~Luce~uL 14 (in FIG. 1).
FIG. 3 illustrates the manner in which FIGS. 1 and 2 10 are ~ ;nPd to form a complete asynchronously re~nfi~rAhle network node embodying the invention. As shown, FIG. 1 is placed 1 ~;AtPly above FIG. 2, with ~nnn~Dct; r1n~ between the two f igures consisting of data path~ 66 and 68.
FIG. 4 shows a complete packet data system 110 which ;nr~ P~ a source node 112, a dest;nAt;~n node 114, a data path 116 from source node 112 to dest;nAt;l~n node 114, and a data path 118 from destination node 118 to source node 112. Source node 112 and dest;nAt;nn node 114 are both asyn,_llru.luusly rec~nf; g--rAhl e packet network nodes embodying the invention and each; nrl llrlPF~ both a transmitting portion 10 (as shown in FIG. 1) and a receiving portion 70 ~as ghown in FIG . 2 ) . E ach of data paths 116 and 118 may, by way of example, take the form of a 1.544 megabit T-1 Carrier rPrPAtPred digital t ~si~n line, supporting 24 time division mult;r~YPd 64 kilobit DS0 rhAnnpl~
FIGS. 5 through 8 illustrate the ~nntPnt~ of frame RAM 26 in source node 112 and frame RAM 80 in degt;nAt;~n node 114, respectively, during s~r~ ive stages of packet band PYrAn~ion in A~C ., ~ e with the invention.
In FIG. 5, frame RAM 26 and frame RAM 80 store, for each of the 24 digital carrier rhAnnPl ~ (DS0 level) supported by a T-1 Carrier digital t ~;,n line, ;~Pnt;f;cAt;~n of the network ;nt~rfAcP, whether packet band or time division 1 t;rl PY, ~Acc~bq~l by that channel. The result, in each frame RAM, is a complete identif ication of the transmit f rame in source node 112 Wo9sns570 21 771 4 1 and the receive frame in dest;nAtinn node 114. Prior to packet band PYpAnAinn, the rnntPnt~ of both frame RAM 26 and frame RAM 80 are t~lPnt; rAl .
By way of illustration, system 110 in FIG. 4 begins with 8 DS0 rhRnnPl ~ A~ nP~l to a 512 kilobit per second packet band (PBND), 8 DS0 channels Aq~;~nPd to a first 512 kilobit per second time division multiplex band (TDM1), and 8 DS0 channels A~s;gnPd to a second 512 kilobit per second time division multiplex band (TDM2).
In practice, there may be more packet bands and more or fewer time division multiplex bands, and the packet bands _nd time division multiplex bands may contain more or ~ewer DS0 channels than shown in the example. As illustrated in FIG. 5, the initial channel lineups, prior to packet band expansion, include DS0 nhAnn~l~ 1, 4, 7, 10, 13, 16, 19, and 22 A~ nPd to TDM1, DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 assigned to TDM2, and DS0 channels 3, 6, 9, 12, 15, 18, 21, and 24 assigned to the packet band (PBND). For synchrnn;7At;nn purposes, both frame RAM 26 and frAme RAM 80 contain a top of fr_me (TOF) marker associated with DS0 channel 1. As illustrated, the channel lineups in both frame RAM 26 and ~rame RAM 80 are originally ;~lPnt;~Al FIG. 6 illustrates the channel lineups in fr_me RAMs 26 and 80 during the first stage of packet band expansion. A disconnect request has been received by time division multiplex ;nter~Ace 20 for each of DS0 ~hAnnP1~ 2, 5, 8, 11, 14, 17, 20, and 23 constituting TDM2 . In frame RAM 26, a pad or tl~ < y character PAD
has replaced the TDM2 designation for each of those newly available DS0 ~ hAnnPl ~. All channel assignments in frame RAM 80 remain the same as in FIG. 5. Dest;nA~;nn node 114 ignores all pad rhArArtPr~ PAD and a channel rPA~ ;n;t;2tinn signal is sent, by way of example, from source node 112 to ~lP~t;nAt;nn node 114 over packet band PBND. Alternatively, the channel rPA~is initiation signal may be sent over any other DS0 channel or nAt;nn of DS0 channels.
~ w095129570 21 77 t 4 1 I`l/L~
FIG . 7 illustrates the channel lineups in f rame RAMs 26 and 80 during the second stage of packet band P'rr~nqi''n- The pad rh~r~rtPrq PAD and the channel rP~qq;3 initiation signal have been received in 5 dest;n~t~nn node 114 but pad ~ilter 86 removes the pad characters PAD before they can be acted upon by PBND
interface 74. The channel lineup in frame RAM 26 remains the same as in FIG . 6, but the channel lineup in f rame RAM 80 has changed 80 that DS0 chlnnPlq 2, 5, 8, 11, 14, 17, 20, and 23 have been disrnnnPctPd from TDM2 and reassig~ed to packet band PBND. At the same time, a channel reassignment acknowls~, signal i8 sent, by way of example, in a packet band from dest;n~t;r~n node 114 to aource node 112 . ~1 t~rn~t~vely, the channel reassignment acknowledg signal may be sent over any other DS0 cha~nel or 'n:-t;r,n of DS0 rh~nnPlq Sixteen DS0 rh~nnPlq (2, 3, 5, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, and 24) are now assigned to packet band PBND in f rame RAM 8 0 . In the ; , packet band 20 PBND has lost no bandwidth, there has been no ;ntPrr~rtion of packet traffic, and no ~y..,l.L.,~ized frame switch has been needed.
FIG. 8 illustrates the channel lineups in random access memories 26 and 80 after packet band PYr~nq;nn has been completed. The chamlel reassignment acknowl~
signal has now been received from dest;n~t;c~n node 114 by source node 112. As illustrated, the channel lineup in frame RAN 80 remains the same as in FIG. 7 and the channel lineup in frame RA~I 26 is the same as that in frame RAM 80. The pad or tllL~ ~ y rh~r~rtPrs PAD have been removed from DS0 rh5lnn"lq, 2, 5, 8, 11, 14, 17, 20, and 23 and those rhP~nnPl q have been reassigned to packet band PBND. I~ both source node 112 and dest;n~t;on node 114, packet band PBND now ncc-lr; Pq both the original packet band DS0 rh~nnPlq 3, 6, 9, 12, 15, 18, 21, and 25 and the dis~ ed TDM2 ch~nnPlq 2, 5, 8, 11, 14, 17, 20, and 23. At this point, packet band P13ND is using the Wogsl29s70 2~77t4~
full h~ntlw;rlth of both the DSO Channel8 of the nr;~;nAl packet band and the original TDM2 DS0 rh~nnPl ~.
FIGS . 9 through 12 illustrate the contents of f rame RAM 26 in source node 112 and frame RAM 80 in de8tinAt;rn 5 node 114, respectively, during surrP~ive stages of packet band, ~ lon in Arrortl~nre with the invention.
In FIG. 9, frame RAM 26 and frame R~M 80 store, for each of the 24 digital carrier channels (DS0 level) supported by a T- 1 Carrier digital i ~ n line, 10 ;~iPnt;fication of the network ;ntPrfAce, whether packet band or time division multiplex, accessed by that channel. The result, in each frame RAM, is once again a complete ;~iPnt;f~cation of the transmit frame in source node 112 and the receive frame in dest;nAt;nn node 114.
15 Prior to packet band compression, the contents of both frame ~AM 26 and frame RAM 80 are originally ;tiPnt;r2l.
By way of ~urther illustration, system 110 in FIG. 4 begins with 16 DS0 rhAnnPl ~: A~si ~nP~l to a 1024 kilobit per second packet band ~PBND) and 8 DS0 channels assigned 20 to a first 512 kilobit per second time division multiplex band (TDM1). In rr~r~tirP, there may be more packet bands and more or fewer time division multiplex bands, and the packet bands and time division multiplex bands may contain more or fewer rh~nnF~l ~ than shown in the example.
25 As illustrated in FIG. 9, the initial channel lineups, prior to packet band: ~ ~s~3ion, include DS0 channels 1, 4, 7, 10, 13, 16, 19, and 22 assigned to TDM1 and DS0 channels 2, 3, 6, 8, 9, 11, 12, 14, 15, 17, 18, 20, 21, 23, and 24 ~ ; gnPd to the packet band (PBI~D) . For 30 synchr--n; 7Ati~n purposes, both frame RAM 26 and frame RAM
80 contain a top of frame (TOF) marker A~or;AtPd with DS0 channel 1. As illustrated, the channel lineups in both frame RAM 26 and frame RAM 80 are ;~lPnt;rAl.
FIG. 10 illustrates the channel lineups in frame 35 RAMs 26 and 80 during the f lrst stage of packet band compression. A connect re~auest has been received by time division multiplex interface 20 for each of DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 constituting TDM2. In 2 ~ 77 t 4 1 ~rame RAM 26, a pad or throw away rh~r~tPr PAD has replaced the PBND ~3P~; gnAt1 r,n ~or each of those no longer available DS0 rh~nnPl ~ . All channel assignments in frame RAM 60 remain the same as in FIG. 9. Dest;n~t;rn node 114 ignores all pad rh~r~rtPr~ PAD and a channel - reassignment initiation signal is sent, by way of example, from source node 112 to dest;n~t;rln node 114 over packet band PBND. Alternatively, the channel reassignment initiation signal may be sent over any other DS0 channel or ;n~t;r,n of DS0 rh;-nnPl~.
FIG. 11 illustrates the channel lineups in frame RAMs 26 and 80 during the second stage of packet band ~ e.-~lon. The pad rh~r~rtpr~ PAD and the channel reassignment signal have been received in des~;nAt;r~n node 114 but pad filter 86 removes the pad rh~r~r~tPr~ PAD
before they can be acted upon by PBND interface 74. The channel lineup in frame RAM 26 remains the same as in FIG. 6, but the channel lineup in frame RAM 80 has changed 80 that DS0 channels 2, 5, 8, 11, 14, 17, 20, and 20 23 have been rl;~rrnnPctPrl from packet band PBND and rP ~ nPrl to TDM2. At the same time, a channel reassignment acknowledy signal is sent, by way of example, in a packet band from dest;n~t;on node 114 to source node 112. Alternatively, the channel rP~
25 acknowledgemeIlt signal may be sent over any other DS0 channel or 'n:-t;rn of DS0 rh~nnPlQ. In frame RAM 80, DS0 rh~nnPl~ 1, 4, 7, 10, 13, 16, 19, and 22 are assigned to TDMl, DS0 rh~nnPl ~ 2, 5, 8, 11, 14, 17, 20, and 23 are assigned to TDM2, and DS0 rh~nnPl~ 3, 6, 9, 12, 15, 18, 30 21, and 24 are ~signP~l to packet band PBND ln frame RAM
80. In the --~ ; , packet band PBND has c~nt;m~Pd to operate at a 512 kilobit per second bit rate (its bit - rate after, _ es~ion), there has been no interruption of packet traffic, and no synchronized frame switch has 3 5 been needed .
FIG. 12 ;llll~tr~tP~ the channel lineups in frame RAMs 26 and 80 after pack band ~ ession has been completed. The channel reaggignment acknowl ~ ~
W095129570 2 ~ 7 7 ~ 4 ~
aignal haa been received from dest;n~t;nn node 114 by source node 112. As illustrated, the charmel lineup in frame RAM 80 remains the same aa in FIG. 11 and the channel lineup in frame RAM 26 is the same as that in frame RAM 80. The pad or throw away nh~r~ct~r~ PAD have been removed from DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23 and thoae rh~nn~-l q have been reasaigned to TDM2.
In both source node 112 and deattn~t~nn node 114, packet band PBND now occupies only DS0 nh~nn~ 3, 6, 9, 12, 15, 18, 21, and 24 and TDM2 now occupiea DS0 channels 2, 5, 8, 11, 14, 17, 20, and 23. Packet band PBND, TDM1, and TDM2 are now all operating at 512 kilobit per aecond bit rates .
Two ~ of actual data streams tranamitted in a packet band from aource node 112 to dest;n~t;nn node 114 during aucc~a~; ve packet band f'Yp~n~i nn and packet band ~a~ion are illuatrated in TABLES 1 and 2 below.
EXAMPLE OF SINGLE C~ANNEL PACRET BAND RYP~ ~ AND
DATA: 24,12,15,62,5A,75,10,27,40 n~ OUT
~5L ~3E~ 8 INACT 8 ADDED 9 ~rTIVE 9 D~OPPED
ESC~5A
REPLACE 5A WITEI 5A, 7A (SEND PBAIN TEXT 5A AS 5A, 7A) REPLACE 24 WITEI 5A, 64 (SEND PI,AIN TEXT 24 AS 5A, 64) ~1 7~ 4 1 ~ WO 95,29570 ~ ........
TA3~iE 1 illustrate~ the manner in which the invention permits a~yllo1lLu.luus packet band PYp~n~inn and e~Dion ~rom the gt:lntlrn;nt of rh~r~rtPr~ actually transmitted ~rom source node 112 to dest;n~t;nn node 114.
5 In this example PYp~n~inn and es,iion both involve only single DS0 rh~nnPl ~. As shown, it is assumed, by way of example, that the data actually being transmitted over the packet band channel consist o~ a sPrl~Pnt;~1 rh~ractPr stream 24,12,1s,62,sA,7s,10,27,40... An actual 10 data stream will contain many additional rh~r~rtPrq, but these will suffice for illustration purposes. It is assumed that the packet band, before P~r~n~inn, consists of DS0 rh~nnPl~ 1, 2, 5, 7, 9, 15, 16, and 17 and that DS0 channel 8 is assigned to a time division multiplex 15 channel. It i8 further assumed, by way o~ example, that 5A is tlP~ign~tP~l as an escape character and that 24 is designated as the pad rh~r~CtPr. To send a plain text 5A, by way of example, the rh~r~rtPr~ actually sent are 5A,7A and to send a plain text 24, by way of example, the 20 rh~ractPr~ actually sent are 5A, 64. For ease of illustration, each column begins with the same sequence o~ data rh~r~rtPr~. In practice, each column would begin with whatever data rh~r?ctpr was being transmitted when the tr;ln~:;t;nn to the status le~Lese~ed by the column 2 5 began .
The first column (DS0) in TAi3I,E 1 irlPnt;~;Pq the DS0 rh;lnnPl~ with Which the example is c~ rPI"Pd. Before packet band PYr~n~inn, the characters shown in the second column (BEFORE) are transmitted in the; n~; r~ted packet 30 band DS0 rh~nnPl ~. DS0 channel 8 is shown blank in the second column because at this stage it is not carrying packet band infnrr-t;on. Note that, because 24 has been Leselved to Le~lése~t the pad rh~r?rtpr~ it has been replaced in the second column by the sP~rlPnre 5A, 64 and 35 that, because 5A has been leselved to represent an escape rh~r~ctPr~ it ha8 been replaced in the second column by the serlllPnre 5A, 7A.
wo95n9s7o 2 ~ 7 7 1 4 1 I_1/L_ ~
me third colum~ ( 8 INACT) in TA3LE 1 shows what happens when DS0 cha~nel 8 goes inactive in L~ ullse to a disconnect request. The pad rh ~r~rt~r 24, which destin~t;r,n node 114 has been yL."_ ' to ignore or discard, is transmitted in DSO channel 8. Pad rh~rPct~r 24 has been it:~l;r~ fl in TABLE 1 for: _h~
me fourth column (8 ADD3D) in TAB3~E 1 shows what happens after DS0 channel 8 has been added to the packet band. Packet band data rh~r~rt~r~ are now tra~smitted in 10 se~l~nre in the respective packet band DSO channels.
me fifth columrl (9 ACTIVE) in TABIE 1 shows what happeIls af ter DS0 channel 9 is about to be preempted by a time division multiplex channel in L_~i~Ull3C to a connect request. Pad rh~r~t~r 24 is transmitted in DS0 channel 15 9 and the packet band data stream is cnnfin~fl to DSO
channels l, 2, 5, 7, 8, 15, 16, and 17.
The sixth column (9 DROPPED) in TABLE 1 shows what happen~ after DS0 channel has been dropped from the packet band channel. The packet band data stream is 20 rr,nf;nPfl to DS0 rh~nn~l~ 1, 2, 5, 7, 8, 15, 16, and 17.
W095129570 2 1 77 ~ 4 ~
BXAMPLE OF PACRET BAND ~ L .~ Sl~
DATA: 24,12,15,62,5A,75,10,27,40 n~T~ OU~ ~
8,10,11 8,10,11 15,16 15,16 ~Q ~ INACT ~= ~E DROPP3D
8 j~ 62 62 62 2~ 7A 7A 7A
1515 5A 5A 10 j~
ESC~5A
PAD~24 20REPLACE 5A WITH 5A, 7A (SEND PIAIN TEXT 5A AS 5A, 7A) REPLACE 24 WITH 5A, 64 (SEND PI,AIN TEXT 24 AS 5A, 64) TABLE 2 further illustrates the manner in which the invention permits a.iy.lcll~ull.,us packet band PYrAn~inn and , _ ession from the stAn~lro;nt of r~hAr~rtpr~ actually transmitted from source node 112 to dest;n~t;on node 114.
In this example PYr~nqir~n and ~ ession both involve multiple DSO rh~nnPl ~ . As shown, it is again assumed, by way of example, that the data actually being transmitted over the packet band channel con8i8t of the 8PqllPnt; Al character stream 24 ,12 ,15, 62, 5A, 75 ,1 0, 2 7, 4 0 . . . An actual data stream will contain many additional -hArArtPrA, but these will suffice for illustration ~uL~08e8. It is again assumed that the packet band, bef ore PYr~n~ n, consists of DSO rhAnnPl~ 1, 2, 5, 7, 9, 15, 16, and 17.
This time, it is assumed that DSO rhAnnPl~ 8, 10, and 11 are assigned to one or more time division multiplex ~ h:lnnPl ~ . It ig again further assumed, by way of w09s/2gs70 2177~4t ~ o o example, that 5A is designated as an escape rhArArtPr and that 24 is ~lP~ign~ted as the pad rhArACtPr. To send a plain text 5A, by way of ex_mple, the rhAr~ACtPrR actually sent are 5A,7A and to send a plain text 24, by way o~
5 example, the rhArArtprs actually sent are 5A, 64. For ease of illustration once more, each column begins with the same ae~lpn~e of data rhAr~ActPrR. In rrA~-t~ce, each column would begin with whatever data rhAractPr was being transmitted when the transition to the status represented 10 by the column began.
The first column (DS0) in TABLB 2 j~lPnt~fiPR the DS0 channels with which the exAmple is rnnrPrnP~. Before packet band PYrAnR~-7n, the characters shown in the second column ~BEFORE) are transmitted in the ~n~l~r~tPd packet band DS0 channelR. DS0 channels 8, 10, and 11 are shown b~Lank in the second column because at this stage they are not carrying packet band infnr~--tinn. Note that, because 24 haR been LeseLved to le~LesellL the pad rhArRctPr, it has been replaced in the second column by the sP~I~nre 5A,64 and that, because 5A has been reserved to LeyLesellL
an escape rhAr~CtPr, it has been replaced in the second column by the 8PrltlPnr~ 5A, 7A.
The third column ( 8 ,10 ,11 INACT) in TA~LE 2 shows what happens when DS0 channels 8, 10, and 11 go inactive in response to disconnect requests. The pad ~hArActPr 24, which dest;nAt1nn node 114 has been ~ u' ' to ignore or discard, is transmitted in DS0 channels 8, 10, and 11. Pad rh~r~rtPr 24 has been italicized in TABLE 2 for --R~ R, .
The fourth column (8,10,11 ADDED) in TAB~E 2 shows what happens after DS0 channels 8, 10, and 11 have been added to the packet band. Packet band data rh;~rArterR
are now transmitted in 8etrl~nre in the respective packet band DS0 rhAnnpl R .
The fifth column (15,16 ACTnrE) in TAB~E 2 shows what happens af ter DS0 channels 15 and 16 are about to be preempted by a time division multiplex channel in le~ e to connect requests. Pad rhAr~rtPr 24 is ~ W0 95129570 2 1 7 7 t ~
t~:~n~--~ ttPd in DS0 ~h~nnPl ~ 15 and 16 aI~d the packet ba~d data stream i8 cr-nfinPcl to DS0 rh~nnPl~ 1, 2, 5, 7, 8, 9, 10, 11, and 17.
The ~ixth column (15,16 DROPPED) in TABLE 1 shows 5 what happen~ after DS0 rh~nnPl ~ 15 and 16 have been dropped from the packet barld chaImel. The packet band data ~tream i~ c~nfinpd to DS0 ~-h~nnPl ~ 1, 2, 5, 7, 8, 9, 10, 11, and 17.
Claims (7)
1. An asynchronously reconfigurable packet network node for transmitting digital message data to a remote packet network node over an outgoing digital transmission path and receiving digital message data from said remote node over an incoming digital transmission path, each of said digital transmission paths comprising plurality of time division multiplexed digital channels and each of aid digital channels having active and inactive states in response to respective channel connect and disconnect requests, said reconfigurable node comprising:
means for assigning to a packet data channel n of said digital channels in said outgoing transmission path, where n is an integer equal to or greater than zero;
means for detecting a status change in the connect/disconnect requests for any of said digital channels in said outgoing transmission path;
means for transmitting predetermined unique pad characters in any of said digital channels in said outgoing transmission path in response to detection of a status change in the respective connect/disconnect requests of such channels, where said pad characters are ignored by said remote node whenever received and the flow of data in said packet data channel continues without interruption;
means for transmitting a channel reassignment initiation signal to said remote node over said outgoing transmission path;
means for receiving a channel reassignment acknowledgment signal from said remote node over said incoming transmission path; and means responsive to receipt of said channel reassignment acknowledgment signal for changing the bandwidth of said packet data channel by changing the assignment with respect to said packet data channel of any of said digital channels in said outgoing transmission path containing said pad characters;
whereby the flow of data in said packet data channel continues without interruption through said bandwidth change.
means for assigning to a packet data channel n of said digital channels in said outgoing transmission path, where n is an integer equal to or greater than zero;
means for detecting a status change in the connect/disconnect requests for any of said digital channels in said outgoing transmission path;
means for transmitting predetermined unique pad characters in any of said digital channels in said outgoing transmission path in response to detection of a status change in the respective connect/disconnect requests of such channels, where said pad characters are ignored by said remote node whenever received and the flow of data in said packet data channel continues without interruption;
means for transmitting a channel reassignment initiation signal to said remote node over said outgoing transmission path;
means for receiving a channel reassignment acknowledgment signal from said remote node over said incoming transmission path; and means responsive to receipt of said channel reassignment acknowledgment signal for changing the bandwidth of said packet data channel by changing the assignment with respect to said packet data channel of any of said digital channels in said outgoing transmission path containing said pad characters;
whereby the flow of data in said packet data channel continues without interruption through said bandwidth change.
2. The asynchronously reconfigurable packet network node of claim 1 in which n is a positive integer and said channel reassignment initiation signal is transmitted over said packet data channel.
3. The asynchronously reconfigurable packet network node of claim 1 in which at least some digital channels in said outgoing transmission path having status changes in their connect/disconnect requests are voice channels.
4. The asynchronously reconfigurable packet network node of claim 1 in which at least some digital channels in said outgoing transmission path having status changes in their connect/disconnect requests comprise a single broad band time division multiplexed channel.
5. The asynchronously reconfigurable packet network node of claim 1 in which at least some digital channels in said outgoing transmission path having status changes in their connect/disconnect requests comprise another packet data channel.
6 . The asynchronously reconfigurable packet network node of claim 1 in which said means for detecting status changes detects disconnect requests, said means for transmitting transmits pad characters in response to detection of respective channel disconnect requests, and said means responsive to receipt expands the bandwidth of said packet data channel by adding any of said digital channels in said outgoing transmission path containing said pad characters to the digital channels assigned to said packet data channel;
whereby the flow of data in said packet data channel continues without interruption through said bandwidth expansion.
whereby the flow of data in said packet data channel continues without interruption through said bandwidth expansion.
7. The asynchronously reconfigurable packet network node of claim 1 in which said means for detecting status changes detects connect requests, said means for transmitting transmits pad characters in response to detection of respective channel connect requests, and said means responsive to receipt contracts the bandwidth of said packet data channel by subtracting from said packet data channel any of said digital channels in said outgoing transmission path containing said pad characters;
whereby the flow of data in said packet data channel continues without interruption through said bandwidth contraction.
whereby the flow of data in said packet data channel continues without interruption through said bandwidth contraction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/232,952 US5467344A (en) | 1994-04-25 | 1994-04-25 | Packet data transmission with asynchronous bandwidth switching |
| US232,952 | 1994-04-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2177141A1 true CA2177141A1 (en) | 1995-11-02 |
Family
ID=22875239
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002177141A Abandoned CA2177141A1 (en) | 1994-04-25 | 1995-04-21 | Packet data transmission with asynchronous bandwidth switching |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5467344A (en) |
| EP (1) | EP0720809B1 (en) |
| AU (1) | AU698020B2 (en) |
| CA (1) | CA2177141A1 (en) |
| DE (1) | DE69513136T2 (en) |
| WO (1) | WO1995029570A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2595904B2 (en) * | 1994-07-06 | 1997-04-02 | 日本電気株式会社 | Demand assignment communication control system |
| DE59507871D1 (en) * | 1994-07-12 | 2000-04-06 | Ascom Ag | Device for switching in digital data networks for asynchronous transfer mode |
| US5561791A (en) * | 1995-04-10 | 1996-10-01 | Digital Equipment Corporation | Method and apparatus for conditioning timed program independent of transport timing |
| US5805595A (en) * | 1996-10-23 | 1998-09-08 | Cisco Systems, Inc. | System and method for communicating packetized data over a channel bank |
| US6510145B1 (en) | 1997-07-25 | 2003-01-21 | Samsung Electronics, Co., Ltd. | Method and apparatus for providing packet data service in a communication system |
| KR100258221B1 (en) | 1997-07-25 | 2000-06-01 | 윤종용 | Ignition method of packet traffic channel for communication system |
| US6011801A (en) * | 1997-10-09 | 2000-01-04 | Timeplex, Inc. | Rate control of channels on a time division multiplex bus |
| US6009106A (en) * | 1997-11-19 | 1999-12-28 | Digi International, Inc. | Dynamic bandwidth allocation within a communications channel |
| US6434166B1 (en) * | 1998-09-10 | 2002-08-13 | Cisco Technology, Inc. | Method for universal channel allocation based on DS-0 channelized format |
| US6781956B1 (en) | 1999-09-17 | 2004-08-24 | Cisco Technology, Inc. | System and method for prioritizing packetized data from a distributed control environment for transmission through a high bandwidth link |
| US7349393B2 (en) * | 1999-12-02 | 2008-03-25 | Verizon Business Global Llc | Method and system for implementing an improved universal packet switching capability in a data switch |
| JP4410921B2 (en) * | 2000-09-22 | 2010-02-10 | 富士通株式会社 | Circuit rearrangement method and circuit therefor |
| US7127653B1 (en) * | 2001-07-05 | 2006-10-24 | Pmc-Sierra, Inc. | Apparatus and method for efficient data transport using transparent framing procedure |
| US7085860B2 (en) * | 2002-01-11 | 2006-08-01 | International Business Machines Corporation | Method and apparatus for a non-disruptive recovery of a single partition in a multipartitioned data processing system |
| US8794458B2 (en) * | 2010-06-28 | 2014-08-05 | Mead Johnson Nutrition Company | Container seal |
| WO2013115798A1 (en) * | 2012-01-31 | 2013-08-08 | Hewlett-Packard Development Company, L.P. | Flexible port configuration based on interface coupling |
| US10957445B2 (en) | 2017-10-05 | 2021-03-23 | Hill-Rom Services, Inc. | Caregiver and staff information system |
| US11316718B1 (en) | 2019-11-08 | 2022-04-26 | Rockwell Collins, Inc. | Dynamic spectrum access control traffic over military radio voice channel |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2162022B (en) * | 1984-07-17 | 1988-03-02 | Stc Plc | Data transmission system |
| DE3580481D1 (en) * | 1985-08-13 | 1990-12-13 | Ibm | MECHANISM FOR THE DYNAMIC ASSIGNMENT OF BANDWIDTH BETWEEN SWITCHING CHANNELS AND PACKET BIT CURRENT IN A MESSAGE NETWORK. |
| US4763319A (en) * | 1986-05-19 | 1988-08-09 | Bell Communications Research, Inc. | Multi-rate synchronous virtual circuit network for voice and data communications |
| US4819226A (en) * | 1987-11-10 | 1989-04-04 | Bell Communications Research, Inc. | Framer circuit for use in a DTDM network |
| JPH021671A (en) * | 1988-03-17 | 1990-01-05 | Toshiba Corp | Load control system for packet switchboard |
| JP2595025B2 (en) * | 1988-03-18 | 1997-03-26 | 株式会社日立製作所 | High-speed packet switching equipment using space division type switches |
| DE3919154A1 (en) * | 1988-05-21 | 1990-12-13 | Telefonbau & Normalzeit Gmbh | Digital data transmission for ring bus communication exchange - accelerating complete cell transmission and reception with transition command by central control with switching mode alteration |
| US4980886A (en) * | 1988-11-03 | 1990-12-25 | Sprint International Communications Corporation | Communication system utilizing dynamically slotted information |
| US4914650A (en) * | 1988-12-06 | 1990-04-03 | American Telephone And Telegraph Company | Bandwidth allocation and congestion control scheme for an integrated voice and data network |
| US5042032A (en) * | 1989-06-23 | 1991-08-20 | At&T Bell Laboratories | Packet route scheduling in a packet cross connect switch system for periodic and statistical packets |
| US5136584A (en) * | 1990-07-11 | 1992-08-04 | At&T Bell Laboratories | Hardware interface to a high-speed multiplexed link |
| US5138440A (en) * | 1990-10-29 | 1992-08-11 | General Instrument Corporation | Method and apparatus for communicating a plurality of asynchronous signals over a digital communication path |
| US5278827A (en) * | 1991-05-28 | 1994-01-11 | British Technology Group Ltd. | Variable data rate channels for digital networks |
-
1994
- 1994-04-25 US US08/232,952 patent/US5467344A/en not_active Expired - Fee Related
-
1995
- 1995-04-21 WO PCT/US1995/004958 patent/WO1995029570A1/en active IP Right Grant
- 1995-04-21 CA CA002177141A patent/CA2177141A1/en not_active Abandoned
- 1995-04-21 EP EP95917626A patent/EP0720809B1/en not_active Expired - Lifetime
- 1995-04-21 AU AU23611/95A patent/AU698020B2/en not_active Ceased
- 1995-04-21 DE DE69513136T patent/DE69513136T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE69513136D1 (en) | 1999-12-09 |
| DE69513136T2 (en) | 2000-06-15 |
| EP0720809B1 (en) | 1999-11-03 |
| AU2361195A (en) | 1995-11-16 |
| US5467344A (en) | 1995-11-14 |
| AU698020B2 (en) | 1998-10-22 |
| EP0720809A1 (en) | 1996-07-10 |
| WO1995029570A1 (en) | 1995-11-02 |
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