Hi Stefano, As much I understand the LDP mapping server functionality the Label-Binding TLV shall be used to map a SR Node-SID-Index with a FEC originated by SR-incapable node.
Now in regular SPRING domain a SR-capable node does not generate one Node-SID-Index for a given node address (loopback) per topology. The index is still one for the address across all topologies. Do you suggest that there should be a Node-SID-Index configured for every topology? If not, then I don¹t see a need of mapping different node-sid-index for the same prefix under different topology. Thanks -Pushpasis On 5/21/15, 10:13 PM, "Stefano Previdi (sprevidi)" <[email protected]> wrote: >Hi Hannes, > >On May 21, 2015, at 4:34 PM, Hannes Gredler <[email protected]> wrote: >> hi stefano, >> >> On Thu, May 21, 2015 at 01:55:07PM +0000, Stefano Previdi (sprevidi) >>wrote: >> | [... ] >> | SP> Can you clarify in a new thread what is your problem in making >>the Binding TLV _not_ MT aware in ISIS ? >> >> very simple explanation: >> >> Binding TLV only carries non-IP (e.g. MPLS labels, SRGB Indexes) >>information >> at no point it carries information which directly affects IP >>forwarding state. > > >it propagates information about paths that are useable in a topology. > > >> in contrast all exisiting MT TLVs carry information which have direct >>relevance >> to the generation of IP forwarding state (e.g. >> -MT-ISREACH affects metrics for IP routes, >> -MT-IPREACH affects advertisment and metrics for IP routes). >> >> what is not clear to me: >> why do we need to augment non-IP advertisments with extensions >> that are only relevant for IP path construction. - >> the intersection between the two seems zero to me. > > >ok, let's try to clarify the point then. > >ISIS is used to propagate information pertaining to prefixes and >topology. This information has been contextualized with the introduction >of MT-ISIS. This resulted into adding a MT-ID to each piece of topology >advertised by ISIS, including prefixes and adjacencies. > >SR introduced the Binding TLV which is also a piece of topology since it >represents a useable path in the topology. > >Therefore, it makes sense to me to add a MT-ID to the Binding TLV. > >Note also that the Binding TLV is used by the Mapping Server. There too, >the information propagated by the Mapping Server MAY be related to a >topology. An example is the deployment of IPv6 using MT-ISIS where all >IPv6 information (prefixes, adjacencies) are advertised within topology >ID 2. It wouldn't make sense to advertise IPv6/SID mappings without any >topology identifier. > >Therefore, to me, it is straightforward to enhance the Binding TLV with >MT capability. > > >> | SP> Also, would you also suggest to make it _not_ MT aware in OSPF ? >>In such case we have to change the OSPF spec. >> >> same reasoning here: in case its not clear what/how to use MT in the >>binding TLV for, we should remove it. > > >well, it looks to me the ospf wg clearly understood and acknowledged the >need of the MT-ID and I believe we did the right thing there. > >Now, I'd be interested to know other people opinion on this (from both >isis and spring wg's). > >s. > > >> >> /hannes >> >> | On May 21, 2015, at 3:26 PM, Hannes Gredler <[email protected]> >>wrote: >> | >> | > hi stefano, >> | > >> | > On Thu, May 21, 2015 at 10:14:20AM +0000, Stefano Previdi >>(sprevidi) wrote: >> | > [ ... ] >> | > | > | SP> why not creating a new thread explaining the issue and >>including isis and spring wg ? >> | > | > >> | > | > HG> thats a good suggestion - please do it ! - >> | > | > HG> we need to be clear on the protocol requirements *before* >>adding >> | > | > HG> protocol extensions. >> | > | >> | > | SP> well, we agreed already at multiple occasions (last one was >>during the meeting in Dallas >> | > | SP> where you and me agreed to add MT support to the Binding TLV) >>so we're inline with the process, right ? >> | > >> | > again this is meant as a friendly reminder to document (e.g. in >>some of the SPRING documents >> | > where you have the pen) how you want to intend to use the MT >>extensions for the binding TLV. >> | > >> | > its not yet clear to me and i'd like to get an answer on this >>before progressing the >> | > protocol extensions in the ISIS and OSPF working groups. >> | > >> | > /hannes >> | > >_______________________________________________ >Isis-wg mailing list >[email protected] >https://www.ietf.org/mailman/listinfo/isis-wg _______________________________________________ spring mailing list [email protected] https://www.ietf.org/mailman/listinfo/spring
