CA2530907C - System and method for re-using wavelengths in an optical network - Google Patents

System and method for re-using wavelengths in an optical network Download PDF

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Publication number
CA2530907C
CA2530907C CA2530907A CA2530907A CA2530907C CA 2530907 C CA2530907 C CA 2530907C CA 2530907 A CA2530907 A CA 2530907A CA 2530907 A CA2530907 A CA 2530907A CA 2530907 C CA2530907 C CA 2530907C
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network
sub
nodes
communications
networks
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CA2530907A
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French (fr)
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CA2530907A1 (en
Inventor
David W. Jenkins
Mark E. Boduch
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Coriant Operations Inc
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Tellabs Operations Inc
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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0227Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0227Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0241Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
    • H04J14/0242Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
    • H04J14/0245Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU
    • H04J14/0246Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU using one wavelength per ONU
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0227Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0241Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
    • H04J14/0242Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
    • H04J14/0249Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
    • H04J14/025Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0278WDM optical network architectures
    • H04J14/0283WDM ring architectures
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0278WDM optical network architectures
    • H04J14/0284WDM mesh architectures
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J14/00Optical multiplex systems
    • H04J14/02Wavelength-division multiplex systems
    • H04J14/0278WDM optical network architectures
    • H04J14/0286WDM hierarchical architectures

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)
  • Small-Scale Networks (AREA)

Abstract

A network design that reduces the number of wavelengths needed to support commmunications in a Wavelength Division Multiplexing (WDM) network is disclosed. Wavelengths are reused in isolated sub-networks that do not share common network paths, allowing for the reduction in cost of the WDM equipment supporting the communications in the network.

Description

-SYSTElvl A,ND..METROD FORIM:USINGWAILLENCir-lS IN AN
FTYCAII.M.3VORK
BACKGROUND OF 'THE INVENTIM4 Wavelength Division Multiplexing (WDM) is a method by which single-mode optical fibers are nsed to carry multiple light waves of clifferent frequencies.
ta In a WDM network many Wavelengths are combined in a single fiber, thus increasing the carrying Capacity of the fiber. Signals are assigned to specific frequencies of light (wavelengths) within a frequency band, This multiplexing of optical wavelengths is analogous to the way radio stations broadcast on different wavelengths as to not interfere with each other. Because each channel is transtained ;s on a different wavelength, a desired channel may be selected using a tuner. WDM
channels (wavelengths) are selected in a similar manner. in a WDM network, all wavelengths are transmitted through a fiber, and decaultiplexed at a receiving end.
The fiber's capacity is an agercgate of the transmitted wavelengths, each wavelength having its own dedicated bandwidth.
20 Dense Wavelength Division Multiplexing (DVVDM) is a Arom network in which wavelengths are spaced more closely than in a coarse WDM network. This provides for a greater overall capacity of the fiber.
WPM may be used with dedicated protection techniques such as a Unidirectional Path Switched Ring (UPSR) in a Synchronous Optical Network 25 (SONET). Such u dedicated protection technicitte Uses dual counter-rotating rings that fonti hi-directional connections between the nodes of the network. A
fully protected bi-directional connection between any two nodes may be established and dedicated to a particular wiwelcngth. A working wavelength travels in one direction, and a protection wavelength travels in the Opposite direction. The working wavelength typically takes a shorter path between the two nodes while the protection 'wavelength takes a longer path. The frequent:), ofthe working and protection WIIvniCrigth$ may be identical, as they travel in opposite directions. Every section of the duel counter-rotating rings ate oceupied by either the working wavelength or the protection wavelength (a section may be defined as the fibers directly connecting two nodes within a ring). Therefore, the working wavelength and the protection wavelength cannot be used to establish any additional connections le between any other two nodes. Additional connections require the use of additional wavelengths.
It should be noted that WDM equipment within a given WDM node can only support a finite number of wavelengths; therefore, there is often an economic benefit associated with limiting the nuttaVr of wavelengths used when designing a WIWI
is network_ SUMMARY OF THE IN VENTION
An embodiment of the present invention includes a network, or corresponding method, with at least four network nodes that are each coupled to at 2a least three network paths. At least two of the at least three network paths couple the network nodes. The network also includes at least two siab-nerworks that each include at least two of the network nodes and use at least one wavelength in common with the other sub-network.
Another embodiment of the present invention includes a network, or 2s corresponding method, with (i) at least one network node coupled to at least four network paths and (ii) at least two sub-networks each including the at least one network node and using al le= one wavelength in common.
BRIEF DESCRIPTION OF TUE DRAWINGS
The foregoing and other objects, features and advantages of the invention win be apparent from the following more particular description of preferred -3,., embodiments of the invention, as illustrated in the accompanying drawings in which like reference diameters refer to the Same parts throughout the different views. The diawing s are not necessarily to scale, emphasis instead being placed upon ilinsnating the principles of the invention.
FIG. 1 is a logical view of a reconfigurable. 2-degree1 optical. add/drop node according to an embodiment of the present invention;
FIG_ 2 is a logical view of a ieconfigurable. 3-degree, optical, add/drop node according to an embodiment of the present invention;
FIG. 3 is a physical perspective of a reconfigurable, 2-degree. optical, ip add/drop node;
F10. 4 is a physical perspective of a reconfigurable, 3-degree. optical.
add/drop node;
FIG. 5 is a network diagram of a multi-ring design using 2-ciegree nodes and 3-dcgree nodes;
FIG. 6 is a block diagram of a drop unit according to an embodiment of the present invention;
FIG. 7 is a block diagram of an add unit =cording to an embodiment of the present invention;
FIG. 8 is a block diagram of a 2-degree node with two, reconfigurable, optical interfaces.
FIG. 9 is a block diagram of a 3-degree node with three, reconfigurable, optical interfaces;
FIG, 10 is a block diagram of a 4-degree node with four, reeonfigurable, optical interfaces, 21 FIG. 11 is a network diagram of a single ring network design utilizing 2-degree nodes;
FIG. 12 is a network diagram of a single ring network design inilizing 2-degree nodes where a fully protected hi-directional connection is established between nodes C and F;
PIG. 13 is a network diagram of a network where nodes B, C. 13, and F (torn FIG. 12 are replaced with 3-degree nodes;
FIG. 14 is a network diagram of a network where nodes 13. C, 0, and F from FIG. 12 are replaced with 4-degree nodes;
FIGS. 15-18 are network diagrams illustrating how mu degree nodes may be added to an existing, single ring, Dwr)m network to mare additional sub-3 network rings that reduce the munher of wavelengths used for communications in The network.
DETAILED DESCRIPTION OF TI-LE INVENTION
A description of preferred embodiments of the invention follows.
30 ACCOrdin8 to some embodiments of the present invention, a total number at wavelengths used in a wpm network may be reduced by designing a network using multi-degree noricts that form multiple stib-networks. Isolated sub-networks that do not share common network paths may reuse the mune wavelengths used for communications within the other sub-networks.
15 An embodiment of the present invention includes a network, or corresponding method. with at least four network nodes that are each coupled to at least three network paths. Al least two of the at least three network paths couple the network nodes. The network also includes at least two sub-network that each include at least two of the network nodes and use at least one wavelength in ar common with the other sub-network.
The sub-networks may use at least one wavelength, in ;addition to the at least one wavelength in common. that supports conmannications between the nodes of different sub-networks. The sub-networks may be ring networks, mesh networks, or a combination thereof as The network may include at least four network paths that couple the network nodes and define a third sub-network, Additional sub-networks may be defined with an addition of an even nomber of network paths. The network paths may themselves include multiple network nodes or sub-networks.
The network nodes may be reconfigurable; that is, they may be used tin, so selectively reconfigure the optical interconnections associated with the network paths_ 'This reconfiguration may be in the optical domain and may be achieved through the use a RccoiZgurable Optical Add/Drop Multiplexers (ROADMs).
-5-.
Additiowilly, the nodes of the network may include add/drop ports alai are used for adding or dropping wavelengths to and from the network.
A network path carries a data stream between network nodes and may be a single fiber for ti-directional traffic or multiple fibers for hi-directional S communications.
Details of the network embodiments described above are presented below in reference To FIGS. $ and 13-18. FIGS. 1-4 and 6-12 illustrate embodiments of nodes, add/drop multiplexeis, and network protection techniques (e_g., lJnictircetional Path Switched Ring (1../PSR)) useful for understanding aspects of the )3 present invention.
F La. 1 illustrates a logical view of a reconfigurable, 2,-degree, optical, add/drop node 100 according to an embodiment of the present invention. The node 100 includes two reeonfigurable optical interfaces (ROW- The ROls are labeled Eltst 110 and West 120 in FIG. 1. F.ach ROI. includes a =hi-wavelength input port )5 130a. 130b and a multi-wavelength output port 1404, 140b. According to one embodixttent, the multi-wavelength parts nansport multiple wavelengths over single fibers I50a, 1501} and 160; 160b by using wavelength division multiplexing (WDM) techniques.
According to an embodiment of the present invention, add and drop ports io (not shown) are associated with each ROI. Multiple wavelengths may be dropped at a given ROI. When wavelengths are dropped, each dropped wavelength is placed on an. individual fiber 170; 170b. It should be appreciated that the single line 170a, 170b in FIG, 1 used to show drops may represent multiple individual fibers.
When wavelengths are added, each added 'wavelength is received on an individual fiber Ig0a, 180h_ It should be appreciated that the single line 180a, 1110b in FIG.
1 used to show adds may represent multiple individual fibers.
A wavelength (%) arriving On the multi-wavelength input port 130a. 130b of a given ROI 110,120 may be directed to either the associated drop poll 170;
170b or may be passed-through TO the multi-wavelength output port 140b, 140a of the ao other ROI 120,110, Pass-through channels / 904,19013 are illustrated in FIG. 1 by the dashed lines. Because the node in FIG. 1 has two ROls, it may be referred to as a 2-degree node (i.e., FIG. 2 illustrates a logical view of a 3-degree node (i.e.. K=3) 200. ROIs 210, 220, and 230 arc labeled East, West. and North, respectively. For this node 200, a wavelength (A) artivin8 on she multi-wavelength input port of a µ'ivcn ROI
may be directed to either the associated drop port or may be passed-through to the S mu-wavelength output ports of either of she two other ROIs, as indicated in FIG.
2.
FIG. 3 illustrates a physical perspective of a node 300. The node 300 includes two ROls 310, 320. The node 300 may be impletnensed as the node 100 shown in FIG. 1. As shown, add units 311 and 321 may he used to add wavelengths to multi-wavacrtgth output ports. At a given ROT 310, these Wavelengths can come from either the add ports or front the drop unit 522 of she other ROI 320, as indicated. Drop units 312 and 322 may be used TO drop wavelengths to individual fibers of an associated drop port. A-1a given 13.01 310, these wavelengths may come from the multi-wavelength input port associated with The given ROI 310.
13 FIG. 4 illustrates a physical perspective of a node 400. The node 400 includes three ROIs 410, 420, and 430. The node 400 may he implemented as she node 200 shown in FIG. 2 and operate in a similar manner as the 2-degree node described in reference to FIG. i FIG. 5 illustrates a multi-ring design 500 using 2-degree nodes and 3-degree nodes, Nodes A 510 and C 510 sire 2-degree nodes. Nodes B $20 and D 540 arc 3-degree nodes. As shown, there are three distinct rings, referred to as Ring 1 550, Ring 2 560, and Ring 3 570, Ring 1 includes nodes A, 13. C. and D. Ring 2 includes nodes A, B. and D. Ring 3 includes nodes B, C and D. The rings 550, 560, 570 share some common paths (or ring sections). For instance, Ring 2 and Ring 3 share a path between nodes 13 and D. According so one embodiment, this implies that the wavelengths used within Ring 2 must be different from she wavelengths used within Ring 3. since all the wavelengths of both of these rings are placed on she same path 580 (i.e.. fiber that runs between nodes B and r)). According to one aspect of this embodiment, this assumes the use of a dedicated fiber optical protection technique Stleb. 145 LTPSR.
FIG. 6 illustnnes a drop unit 600 according, to an embodiment of the present invention. The drop unit 600 may he implemented as One of she drop units illustrated in FIGS. 3 and 4. The optical directivity element 610 may be used to direct wavelengths (MXIP) arriving via a fiber 605 on the multi-wavelength input port 607 to its various multi-wavelength output ports 615. This may be achieved through the utilization of apical switches, optical couplers. or other appropriate s technologies (not shown). The wavelengths exiting the lower multi-wavelength output port 617 of the optical directivity element 610 are sent to a wpm de-multiplexer 620, The WM/ de-multiplexer 620 de-multiplexes the WDIV1 signal into its individual wavelengths (S).DP/ - SIDPN) and directs each wavelength to a specific individual fiber. fiecause there are N possible wavelengths carried within ie the multi-wavelength parts, the dc-multiplexer 620 supports up in N
"drop" fibers 630, Wavelengths (WOE/ ¨ ?MORK 1) that arc not dropped may be directed via output fibers 640 to one or more of the other multi-wavelength output ports 615 on the drop unit 600.
FIG. 7 illustrates an add unit 700 according to an embodiment of the present invention. The add unit 700 may be implemented as one of the add units illustrated in FIGS. 3 and 4. A set of WDM de-multiplexers 710 (such its an Arrayed Waveguide Grating (AWG)) arc used to de-multiplex the wavelengths (M1J14/ ¨
MXI.F'K) arriving on multi-wavelength input ports 705 into individual wavelengths XN). The wavelengths are then sent to a set off,/ K-to-1 optical switches 720, ra In some embodiments, there is one switeh associated with each of The N
wavelengths. Therefore, the source of a given wavelength OR a multi-wavelength output port 750 of a WI)M multiplexer (MT.JX) 740 can come from any of the le.-multi-wavelength input ports 705 or from the individual single wavelength add ports 707. as shown, Once the switches select a given wavelength, the selected 25 wavelengths can be "power balanced" via the set of N adjustable attenuators 730.
FIG. 8 illustrates a 2-clegree node 800 with two ROls 81 0a, 81 Ob. each including both an add unit 820a, 820b and a drop unit 830a, 8301).
FIG. 9 illustrates a 3-degree node 900 with three ROls 910a, 91 Ob, 910c, each including both an add Unit 920a, 920b, 920c and a drop unit 930e. 930b, 930c.
FIG. 10 illustrates a 4-degree node 1000 with four ROIs 1010; 1010b, 1010e, 1010d, each including both an add unit 1020a. I020b, 1020cõ 1020d and a drop unit 1Q30; 1030b, 1030e, 10304.
FIG, II illustrates a single nag network design 1100 utilizing 2-degree nodes 1110a-f. Tic network 1100 includes dual "counter-rointing" rings 1105a, 1105b, Dual counter rotating rings are used in dedicated protection techniques such tts UPSR. A bi-directional connection between two nodes (e.g., nodes 1110a and FIG. 12 shows an example network having working and protection WDM equipment within a given WDM node can only support a futile number a wavelengths (e.g., 4 wavelengths, 3 wavelengths, or 12 wavelengths, 25 bidireetiOnal counections between ever) pair of nodes (e.g., using UPSR
protection).
As illustrated in Table 1 below, a total of fifteen wavelengths are needed to establish all the connections.
Connection Wavelength Number Ring A 1 main Outer Ring A-C X 2 Main Outer Ring A-D 1 Main Outer Ring A-E X 4 Math Outer Ring A-F X 5 Main Outer Ring B-C X 6 Main Outer Ring B-I) X 7 Main Outer Ring B-E X 8 Main Outer Ring A-F X 9 Main Outer Ring C-D X 10 Ivtairs Outer Ring CE X 11 Main outer Ring X 12 Main Outer Ring D-F X 13 Main outer Ring D-F X 14 Main Outer Ring E-F. - _______________________ X 15 Main Outer Ring Table 1 FIG. 13 illustrates a network 1300 where nodes B, C. D. and F flora FIG. 12 are replaced with 3-clegrec nodes. In this embodiment, two "isolated" 11lb-rings are formed: Sub-Ring 1310 and Sub Ring3 1330. These sub-rings may be referred to s as -hiulated sub-rirt8S" because they share no common ring sections.
Another sub-ring, Sub-Ring 2 1320, is also formed. In FIG. 13, Sub-Ring 3 1330 includes the sub-ring fonued by nodes A. B, and C; Sub-Ring 1 1310 includes the sub-ring formed by nodes ID, B. and F; and Sub-Ring 2 1320 includes she sub-ring formed by nodes B, C, D, and F. Sub-rings that arc isolated from 013C another (e.g. Sub-Rings 1 and 3) may use the same wavelengths to establish connections between the nodes of their associated sub-rings. For ingranCe, in FIG. 13 a connection may be established between nodes D and E on Sub-Ring 11310 using wavelength number I
(Al), while this same wavelength number 1 (41) can simultaneously be used to establish a connection between nodes A and B on Sub-Ring 3 1.330.
Aq an rxtimpIe of hew the number of wavelengths may be reduced by utilizing the four 3-degree nodes. suppose that a network such as she network shown in FIG. 13 is used so establish folly protected bidirectional connections between every pair of nodes (e.g., using UPSR protection). As illustnned in Table 2 below, a total of twelve wavelengths may he used to establish all the connections.
Therefore, three wavelern,,,tlis are saved by using the 3-degree nodes shown in FIG.
13 (as compared to using only 2-degree nodes). In this example, Sub-Ring 1 and Sub-Ring 3 use three wavelengths in common, namely wavelength numbers 1, 2, aria 3.
Connection Wavelength NOMber Ring A-B X 1. Sub-Ring 3 A-C X 2 Sub Ring 3 ¨,---A-D X 4 Main Outer Ring A-E X 5 IViain Outer Ring A-F X 6 Main OW= Ring 13-C X 3 Sub-Ring 3 B-D X 7 MairiZwer Ring .13-E A 8 Main 01;icr Ring B-F X 9 Main Outer Ring Main Outzr Ring C-13 All Main Outer Ring C-F X12 Main Outer Ring D-B X 1 Sub-Ring 1 D-F X 2 Sub-Ring _______________________________________________ -E-F X 3Sub-Ring 1 'Lit-707-- ¨
Sub-Ring 1 1310 and Sub-Ring 3 1330 may 0Se the same wavelengths for communications between their nodes because they are isolated from each other (e.g., s wavelength number 1 (X1) is used for communications between both nodes A
and B, and D and E). Sub-Ring 2 1320 may not use thc same wavelengths as Sub-Ring I
1310 or Sub-Ring 3 1330 because Sub-Ring 2 1320 ShaZeS network paTINin common with Sub-Ring 1 1310 and Sub-Ring 3 1330 (e.g., the paths between nodes B end C, and the paths between nodes D and F), instead, Sub-Ring 2 1320 must use is wavelengths that arc not used by either Sub-Ring 33310 or Sub-Ring 3 1330 (e.g., wavelength number 7 (X7) is used for communications between nodes 13 and D).
Communications berwcen nodes of clilYerent sub-rings coniuninications along a main atm ting 1340) must use wavelengths that are not used by any of the sub rings (e.g., wavelength number 4 (14) is used for communications between nodes A
13 and D), FIG. 14 illustrates a network 1400 where nodes B. C. I), and F from FIG. 12 are replaced with 4-degree nodes with the extra degrees used to create two additional links using ber pairs dimmed from node B to node C and from node 1) to node F.
In this embcxliment, three -isolated" 51k-ritle5 ;Ire formed: Sub-Ring 1 1410, Sub-Ring 2 1420, and Sub-Ring 31430. In FM. 14, Sub-Ring 3 1430 includes the sub-ring formed by nodes A, B, and C using vertical fiber paths T .and V. Sub-king 1420 includes a sub-ring formed by nodes B. C. D. and F using vertical fiber paths s W and X. Sub-Ring I 1410 includes a sub-ring formed by nodes E. and F
using vcrticel fiber paths Y and Z.
LU1 exarnple of how the number or wavelengths may be reduced by utilizing the four 4-clegroe nodes. suppoge that a network such as the zuttwork 1400 shown in FIG. 14 .S used To establish fully protected bidirectional connections to between every pair of nodes (e.g., using MISR protection). As illustrated in Table 3 below, a total of nine wavelengths may be used to establish all the connections.
Therefore, six wavelengths are saved by using the 4-degree nodes shown in FIG.

(.4$ Compared to using only 2-degree nodes). In this example. Sub-Ring 1. Sub-Ring 2, and Sub-Ring 3 use three wavelengths in common, namely wavelength numbers 15 1, 2, and 3.
Connection Wavelength Number Ring A-B 1 Sub-Ring 3 A-C ;c. 2 Sub-Ring 3 A-D 13 Main Outer Ring A-E 6 Main Outer Ring A-14 A 7 Main Outer Ring D-C 13 Sub-Ring 3 13-D A 1 Sub-Ring 2 13-E 18 Main Outer Ring B-F 12 Sub-Ring 2 C-C) 13 Sub-Ring 2 C-F 19 Main Outer Ring C-F 14 Sub-Ring 2 D-E 11 Sub-Ring I
D-F A 2 Sub-Ring 1 Sub-Ring-1 ____________________ ¨
Table 3 Because each sub-ring is isolated from the other sub-rings, the same wavelengths may be used in each of the sub-rings (e.g, wavelength number 1 Q.1) may be used for communications berween nodes A and B. nodes B and D, and nodes D and E). Sub-Ring 2 1420 uses tui additional wavelength because it includes foot s nodes (e.g., wavelength number 4 (X.4) may be used for communications between nodes C and F). It should be noted that ?A can be reused in sub-ring 3 in order to transport additional traffic between two nodes on sub-ring 3. Similarly, A.4 can he reused in 5;b-ring] in order to transport additional 'traffic between two nodes on sub-ring 1. Communications between nodes of different sub-rings must use to wavelengths that are not used by any of the sub-rings (e.g., wavelength number (KS) is used for communications between nodes A and E).
Additional isolated sub-networks may be created by adding To the network 1400 an even number ot paths that couple at least two of the mufti-degree nodes.
For example, in FIG. 14, an additional isolated sub-ring may be created with an 15 addition of two paths that couple any two of the 4-degiee nodes. Both of the newly coupled nodes thug become 6-degree nodes.
FIGS_ 15-18 illustrate how multi-degree nodes may be added to an existing, single ring, DWDIvt network to create additional sub-ring networks to reduce the number of wavelengths needed for communications in the network.
20 rio. 15 is an illustration of an exisTing, single ring, Dw-Dm network cOntAining nodes A-L. Many wavelengths are needed for communications between the nodes_ A thick dashed line illustrates an exemplary ring 1510 within the network.
FIQ. 16 illustrates a designation 1610, 1620, 1630 and 1640 of nodes C. F.
25 and K. respectively. in Ring 1 that arc replaced with 4-degree nodes FIG. 17 illustrateT.,anaddition of."eut-throlighbers= 1710,- 1-720 rola= tiug The new 4-degree nodes C, E, 1, and K. Two fiber pairs may be used for each cut-Tluougli to prevent wavelength blocking by creating isolated sub-networks. The addirion of the cut-throughs creates three, new, isolated sub-network rings 1730.
39 1740, 1750.
FIG. 18 is a perspective of the resulting DWDM network that contains a Total of four rings. Rings 1-3 1730. 1740, 1750 are The newly created rings, while Ring 4 1510 is the original. Network traffic may be routed so that each demand traverses only one ring. This reduces the number of wavelengths that are needed for communications in the network.
In the description above, for purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to one skilled in the art that specific details in the description may not be required to practice the embodiments of the present invention. In other instances, well-known components are shown in block diagram form to avoid obscuring embodiments of the present invention unnecessarily.
In the foregoing specification, embodiments of the invention have been described with reference to specific exemplary embodiments thereof. The scope of the claims should not be limited by particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense.
While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims (22)

1. A network, comprising:
at least four network nodes each coupled to at least four network paths, at least four of the network paths used to couple the at least four network nodes; and at least three isolated sub-networks each including different ones of the network paths and using at least one wavelength in common, at least two of the sub-networks each including at least two of the at least four network nodes that others of the at least two sub-networks do not include, and at least one of the sub-networks including at least four of the network nodes.
2. The network of Claim 1 wherein at least two of the at least four network nodes are coupled by an additional even number of network paths, each pair of the additional network paths forming an additional isolated sub-network.
3. The network of Claim 1 wherein the at least four network nodes are reconfigurable in an optical domain.
4. The network of Claim 1 wherein at least one of the network paths includes multiple network nodes or sub-networks.
5. The network of Claim 1 wherein at least one of the at least four network nodes includes at least one add/drop port.
6. The network of Claim 1 wherein the sub-networks are ring networks, mesh networks, or a combination of ring networks and mesh networks.
7. The network of Claim 1 wherein at least two of the sub-networks use at least one wavelength, in addition to the at least one wavelength in common, supporting communications between nodes of the at least two sub-networks.
8. A method of supporting communications in a network including four network nodes each being coupled to four network paths, the four network nodes being coupled by at least four of the network paths, the method comprising:
carrying first communications on at least one given wavelength in a first isolated sub-network of the network, the first communications being carried through two of the four network nodes and through a first pair of the network paths;
carrying second communications on the at least one given wavelength in a second isolated sub-network of the network, the second communications being carried through the other two of the four network nodes and through a second pair of the network paths;
carrying third communications on the at least one given wavelength in a third isolated sub-network of the network, the third communications being carried through the four network nodes and through four of the network paths other than the first and second pairs of network paths; and carrying fourth communications on at least one wavelength, in addition to the at least one given wavelength, between two of the isolated sub-networks, the first, second, third, and fourth communications being concurrently carried in the network.
9. The method of Claim 8 further including carrying additional communications through an additional even number of network paths coupled to two of the network nodes, each pair of the additional network paths forming an additional isolated sub-network.
10. The method of Claim 8 further including optically reconfiguring the network paths.
11. The method of Claim 8 wherein carrying first communications includes carrying the first communications through multiple network nodes or sub-networks.
12. The method of Claim 8 wherein carrying first communications includes adding or dropping wavelengths to or from the first sub-network.
13. The method of Claim 8 wherein carrying first communications includes carrying the first communications in a sub-network that is a ring network, a mesh network, or a combination of ring networks and mesh networks.
14. A method of supporting communications in a network, comprising:
carrying first communications on at least one given wavelength in a first sub-network of the network, the first communications being carried through at least two network nodes coupled by at least four network paths and through at least two of the at least four network paths;
carrying second communications on the at least one given wavelength in a second sub-network of the network, the second communications being carried through the at least two network nodes and through at least two other paths of the at least four network paths;
carrying third communications on at least one wavelength, in addition to the at least one given wavelength, between the first sub-network and the second sub-network, the first, second, and third communications being concurrently carried in the network; and carrying additional communications through the at least two network nodes and through at least two additional paths defining a third sub-network, the additional communications being carried on the at least one given wavelength in the third sub-network.
15. A network, comprising:
at least two network nodes each coupled to at least four network paths, at least two of the at least four network paths coupling the at least two network nodes;
at least two isolated sub-networks each including at least two of the network nodes, the at least two isolated sub-networks using at least one wavelength in common; and at least two additional network nodes each coupled to at least four network paths, the at least two additional network nodes coupled to the at least two network nodes by at least two of the network paths and coupled by at least two others of the network paths, at least four of the network paths (i) interconnecting the at least two additional network nodes with the at least two network nodes and (ii) defining a third isolated sub-network.
16. The network of Claim 15 wherein the at least two network nodes are coupled by an additional even number of network paths, each pair of the additional network paths forming an additional isolated sub-network.
17. The network of Claim 15 wherein the at least two network nodes are reconfigurable in an optical domain.
18. The network of Claim 15 wherein at least one of the at least two network nodes includes at least one add/drop port.
19. The network of Claim 15 wherein the sub-networks are ring networks, mesh networks, or a combination of ring networks and mesh networks.
20. The network of Claim 15 wherein at least two of the sub-networks use at least one wavelength, in addition to the at least one wavelength in common, supporting communications between nodes of the at least two sub-networks.
21. A network, comprising:
four network nodes each coupled to four network paths and coupled by four of the network paths; and three isolated sub-networks each including different ones of the network paths and using at least one wavelength in common, two of the sub-networks each including two of the four network nodes that the other sub-network does not include, and one of the sub-networks including the four network nodes.
22. A method of supporting communications in a network having two-degree nodes coupled by network paths, the method comprising:
replacing four two-degree nodes of the network with four four-degree nodes;
coupling two pairs of the four-degree nodes each with two additional network paths to create first, second, and third isolated sub-networks;
carrying first communications on a given wavelength in the first sub-network;
carrying second communications on the given wavelength in the second sub-network; and carrying third communications on the given wavelength in the third sub-network, the first, second, and third communications being concurrently carried in the first, second, and third sub-networks.
CA2530907A 2005-12-20 2005-12-20 System and method for re-using wavelengths in an optical network Expired - Fee Related CA2530907C (en)

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