1 Overview of MS-SPRing and GMPLS Multiplex Section - Shared Protection Ring Prepared by: –Diego Caviglia – –Huub van Helvoort – Background reading: draft-caviglia-gmpls-msspring-req

2 Overview of MS-SPRing - Introduction Multiplex Section - Shared Protection Ring – MS- SPRing Protects the multiplex sections (lines) in a ring configuration. –2-fiber sections –4-fiber sections The protection capability of the ring is shared –If no protection required it can be used for extra traffic –The size around the ring is equal to largest working capability on any section of the ring

3 Overview of MS-SPRing - MS-SPRing 2-fiber A working traffic protecting traffic B C D E F

4 Overview of MS-SPRing - MS-SPRing 4-fiber A B C D E F working traffic protecting traffic

5 Overview of MS-SPRing - MS-SPRing 4-fiber A B C D E F working traffic protecting traffic

6 Overview of MS-SPRing - MS-SPRing 4-fiber (ring-switching) A B C D E F working traffic protecting traffic

7 Overview of MS-SPRing - MS-SPRing 4-fiber (ring-switching) A B C D E F working traffic protecting traffic

8 Overview of MS-SPRing - MS-SPRing 4-fiber transoceanic(ring-switching) A B C D E F working traffic protecting traffic

9 Overview of MS-SPRing - MS-SPRing 4-fiber (span-switching) A B C D E F working traffic protecting traffic

10 Overview of MS-SPRing - MS-SPRing 4-fiber (span-switching) A B C D E F working traffic protecting traffic

11 Overview of MS-SPRing - Provisioning Ring topology: every node in the ring is assigned a unique identifier; Used by the APS protocol Traffic matrix: represents the allocation of transport entities in the ring; Used to determine required protection capability Squelching map: represents the connection matrix of the ring; Used to prevent mis-connections in case of ring node failure/isolation

12 How does this relate to GMPLS? GMPLS provides ideally a robust and flexible control plane protocols set designed for application over generalized transport network; A typical application of GMPLS is, among others, the control of transport networks based on SDH/SONET technology; The typical SDH/SONET network topology is made by interconnected rings; the main protection scheme for interconnected rings is MS-SPRing; Usually network operators: Don’t want to dismiss protection scheme they are used to; Wants to sell high value services that need recovery time, at least for the first failure, in order of milliseconds (e.g. 50 ms); In this scenario, the introduction of GMPLS based control plane should ensure support of and/or compatibility with the most important and widely exploited SDH/SONET features, making possible a seamless interworking with inherent data plane requirements.

13 What signaling/routing problems arise? In general, when setting up and configuring a data plane circuit traversing a MS-SPRing ring (or segments of it) via traditional management plane control, special constraints, which are specific to this kind of technology, have to be considered in order to ensure its correct operation; The same constraints have to be carefully taken into account when the data plane circuit is no more set up in a traditional way, but through a GMPLS based control plane; The specific constraints imposed by MS-SPRing are related to: Time Slot Interchange (TSI) Ring Map filling in case of squelching

14 What signaling/routing problems arise? - TSI TSI is the connection function capability of changing the time slot position of through-connected traffic (i.e. traffic that is not added or dropped from the node); At present there is no TSI capability specified in nodes belonging to a MS-SPRing sub network; Channels at MS-SPRing node’s egress are nailed to the same timeslot used by the same channels at node’s ingress; From a Control Plane point of view that means that Ring Ingress Node (first Node of the LSP that is also part of a MS-SPRing) should know in advance witch labels (Timeslots) are free on the ring or some crankback mechanism should be implemented inside the ring.

15 What signaling/routing problems arise? - Squelching Squelching is defined as the process of inserting AU-AIS in order to prevent misconnections; The squelching process application over traffic results in an all 1’s signal; In order to perform squelching each TNEs in the ring should know, for every LSP, wich TNE is Ring Ingress and witch one is Ring Egress; From a Control Plane point of view that means that during the LSP set the above information is distributed among the TNEs that are traversed by the LSP.

16 What signaling/routing problems arise? – Data Plane Control Plane misalignment Before failures The LSP goes through A, B, C and D; The data traffic goes through A, B, C and D; After failure The LSP goes through A, B, C and D; The data traffic goes through A, B, A, F, E, D, C and D Control Plane Needs to be re-aligned with data plane A B C D E F A B C D E F

17 Next Questions