Hi Les,
On 8/26/15, 8:49 PM, "Les Ginsberg (ginsberg)" <[email protected]> wrote: >Pushpasis - > >> -----Original Message----- >> From: spring [mailto:[email protected]] On Behalf Of Pushpasis Sarkar >> Sent: Wednesday, August 26, 2015 7:44 AM >> To: Les Ginsberg (ginsberg); [email protected]; Uma >> Chunduri; Peter Psenak (ppsenak); Eric Rosen; SPRING WG >> Subject: Re: [spring] SRGBs, indexes, and topologies within a domain >> >> Hi Les, >> >> >> >> >> On 8/26/15, 7:45 PM, "Les Ginsberg (ginsberg)" <[email protected]> >> wrote: >> >> >Stephane - >> > >> >Implementations based on the drafts that currently exist advertise a >> topology independent SRGB. A SID which is advertised in a specific MT Prefix >> Reachability advertisement is interpreted as an index into the topology >> independent SRGB. This is NOT compatible with an implementation which is >> written assuming that a SID is an index into a topology specific SRGB. So the >> introduction of topology specific SRGBs would have to be supported >> network-wide before it could be deployed. Sub-TLVs cannot resolve this >> incompatibility. >> [Pushpasis] What if we use the current SR-capability sub-TLVs only for single >> topology deployments? And use a new MT-SR-Capability SubTLV for MT >> deployments? Please note, I am not saying MT cannot be supported with >> current SR-Cap SubTLV. It can be, but with the limitation (as I like to see >> this >> cuurently) is that we MUST use separate SID-index for the same prefix in >> separate topologies. If operator does not want to live with the limitation >> then all the vendor implementations must implement the new MT-SR-Cap >> SubTLV and make it happen. If the operator can live with the implementation >> they continue with per-topology SID-index and single SRGB for all topology. > >[Les:] What you propose does not alter the fact that unless all >implementations agree that SIDs in MT prefix advertisements have to be applied >against a topology specific SRGB we will have interoperability problems. So >the specs have to be revised and the implementations have to be revised to >match. >Existing code will not interoperate. [Pushpasis] My understanding is that in such partial deployment of this proposal it will still work if operator still used distinct indexes per-topology. However to use the same index for the same prefix across all the topologies all the nodes in the network needs to be upgraded to the new proposal. It will be better if we introduce this right away. Further delay will only result in complicating things in future. Thanks -Pushpasis > > Les > >> >> Thanks >> -Pushpasis >> >> > >> > Les >> > >> > >> >> -----Original Message----- >> >> From: spring [mailto:[email protected]] On Behalf Of >> >> [email protected] >> >> Sent: Wednesday, August 26, 2015 12:25 AM >> >> To: Pushpasis Sarkar; Les Ginsberg (ginsberg); Uma Chunduri; Peter >> >> Psenak (ppsenak); Eric Rosen; SPRING WG >> >> Subject: Re: [spring] SRGBs, indexes, and topologies within a domain >> >> >> >> Hi Pushpasis, >> >> >> >> I just want to remember that the discussion is not only for MT, but >> >> there was also a thread for per algorithm SRGB (as presented in >> >> Prague). IMO, there must be some consistency in the choice we do. >> >> Regarding encoding nothing is impossible (as example a new subTLV can >> >> be created ensuring backward compatibility). >> >> I would say let's first have a consensus of what is good to do >> >> independently of the encoding. >> >> >> >> Best Regards, >> >> >> >> -----Original Message----- >> >> From: Pushpasis Sarkar [mailto:[email protected]] >> >> Sent: Wednesday, August 26, 2015 07:36 >> >> To: Les Ginsberg (ginsberg); Uma Chunduri; LITKOWSKI Stephane >> >> SCE/IBNF; Peter Psenak (ppsenak); Eric Rosen; SPRING WG >> >> Subject: Re: [spring] SRGBs, indexes, and topologies within a domain >> >> >> >> Hi Les, >> >> >> >> >> >> >> >> >> >> On 8/26/15, 7:13 AM, "Les Ginsberg (ginsberg)" <[email protected]> >> >> wrote: >> >> >> >> >[Les:] Topology specific SRGBs requires a specification change for the >> IGPs. >> >> The new advertisements are NOT backwards compatible w existing >> >> implementations. So we cannot simply say "do what you please". >> >> >Peter has repeatedly made this point - and also pointed out that >> >> >since the >> >> prefix advertisements as currently defined in the IGP drafts includes >> >> topology identifiers including the topology identifier in the SRGB >> >> advertisement is redundant. >> >> [Pushpasis] Why not add a MT-SR_Capability Sub/TLV then? That way it >> >> won’t break backward compatibility? >> >> >> >> Thanks >> >> -Pushpasis >> >> >> >> >> __________________________________________________________ >> >> >> __________________________________________________________ >> >> _____ >> >> >> >> Ce message et ses pieces jointes peuvent contenir des informations >> >> confidentielles ou privilegiees et ne doivent donc pas etre diffuses, >> >> exploites ou copies sans autorisation. Si vous avez recu ce message >> >> par erreur, veuillez le signaler a l'expediteur et le detruire ainsi >> >> que les pieces jointes. 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