Dear Authors, Ordinary BGP services use "BGP Path Attributes" (with MP_REACH_NLRI and Extended Communities inside Path Attribute). SRv6 needs additionally to explain the structure of SID. "BGP Prefix SID TLV" was chosen for this task. This TLV is at the same BGP level, not inside Path Attribute. So far so good.
I am trying to understand how the correlation should be done between routes sent inside "Path Attributes" and SID structure sent inside "Prefix SID TLV". 1. Potentially it is possible to send the SID structure 1 time. Remote PE could calculate "Label Filed" by transposition scheme out of full SID and put it in some table. Then for every route received in Path Attribute it would be possible to check that such "Label Filed" is already known from this next hop. If known then it is possible to reconstruct full SID and use it for SRH or whatever. 2. The alternative solution is to always supply "BGP Prefix SID TLV" together with every route in "BGP Path Attributes". (chatty approach) Then a separate table is not needed - it is possible to derive SID directly out of "BGP Prefix SID TLV" that is always attached to the route. I have not understood what strategy is assumed by "draft-ietf-bess-srv6-services". I have not found any recommendation on this matter. Potentially it could create an interoperability issue if one side would choose option 1, but the remote side would be capable only to option 2. [cid:image001.png@01D3A7DF.E7D86320] Best Regards Eduard Vasilenko Senior Architect Europe Standardization & Industry Development Department Tel: +7(985) 910-1105, +7(916) 800-5506
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