Re: [Tsv-art] Tsvart last call review of draft-ietf-idr-te-pm-bgp-15

[Alvaro Retana <[e-mail]>]

On December 14, 2018 at 9:49:28 AM, Susan Hares ([e-mail]) wrote:

Sue:

Hi!

I think we might be talking about two different things…or I got lost, which
is completely possible. :-)

I think Yoshi is asking about the format of the TLVs, which happens to be
the same as the OSPF ones (rfc7471), but slightly different than ISIS
(rfc7810bis): the type and length fields are different.  I had already
pointed this out in my AD review, so the text changed from "The semantic of
the TLV is described in [RFC7810] and [RFC7471]” (in -14) to "The semantics
of the value field in the TLV are described in
[I-D.ietf-lsr-isis-rfc7810bis] and [RFC7471]” (in -15)…and the text about
"TLV formats follow the rules defined in [RFC7752]” was added, as Les
pointed out.  I think this is enough.

When you say "align with IGP TLVs”, are you talking about the format of the
TLV, or are you referring to something else?

In some BGP-LS document I’ve seen tables that map the BGP-LS TLVs to the
corresponding ISIS/OSPF TLVs — with the understanding that the format is
different.  One such example is in §2.4/2.5
of draft-ietf-idr-bgp-ls-segment-routing-ext [1].  Is that the alignment
you’re asking about?  If so, then I think that such a table would be useful.

Thanks!

Alvaro.


[1]
https://tools.ietf.org/html/draft-ietf-idr-bgp-ls-segment-routing-ext-11#section-2.4




You both raised two sides of the issue regarding the BGP-LS TLVs when these
TLVs align with IGP TLVs.



Side 1: It is helpful to note that the TLVs are the same

Side 2: It is confusing to have this information in individual drafts.



This is not a single draft issue but a concern regarding several drafts in
the BGP-LS series from IDR.



Yoshi -  Would it help the clarity of the BGP-LS series to have an
explanatory draft that indicates the places to find the alignment?  Or
should we suggest a note to IANA registration to provide clarity.



Thank you for raising both sides of this issue.   Your IDR chairs and AD
have been discussing how to make this easier to understand for implementers
and those who deploy the BGP-LS code.