Re: [Idr] John Scudder's Discuss on draft-ietf-idr-bgp-ls-app-specific-attr-11: (with DISCUSS and COMMENT)

[John Scudder <[e-mail]>]

Hi Ketan,

Sorry for the delay while I swapped the context back in. 

I think the §4 (2.C) text is clear now. Thank you!

I have a question about the §4.1 example you added, I’m afraid (sorry). Here’s the text from -14:

   The corresponding BGP-LS advertisements for that link are determined
   as follows:

   First, based on rule (1), the advertisements are conveyed to BGP-LS
   to get the following:

   1.  ASLA with S, F, and X bits set on it carrying link attributes
       from IS-IS advertisement (a)

   2.  ASLA SRLG with zero-length bit masks with a set of SRLGs from IS-
       IS advertisement (b)

   3.  ASLA SRLG with the X bit set on it with a set of SRLGs from IS-IS
       advertisement (c)

   The next rule that applies is (2)(c) and it is determined that
   collation is required for applications S and F; therefore, we get the
   following:

   1.  ASLA with the S bit set on it carrying link attributes from IS-IS
       advertisement (a) and SRLGs from IS-IS advertisement (b) (this is
       collation for application S based on (2)(c))

   2.  ASLA with the F bit set on it carrying link attributes from IS-IS
       advertisement (a) and SRLGs from IS-IS advertisement (b) (this is
       collation for application F based on (2)(c))

   3.  ASLA with the X bit set on it carrying link attributes from IS-IS
       advertisement (a) (remaining application not affected by
       collation based on (2)(c))

   4.  ASLA SRLG with zero-length bit masks with SRLGs from IS-IS
       advertisement (b) (not affected by (2)(c))

   5.  ASLA SRLG with the X bit set on it with SRLGs from IS-IS
       advertisement (c) (not affected by (2)(c))

I think what you’re saying is that a naive implementation will emit a total of eight (ASLA or ASLA SRLG), right? The first list 1-3, plus the second list 1-5? You’re not saying that the second list 1-5 is the final output, with list 1-3 having been an intermediate result?

If that’s your intent, I think it would be clearer if you numbered the items 1-8, so first 1-3 and then 4-8 instead of restarting the numbering. This is especially the case because you follow it with a third list, 1-4, which *is* a distinct set of (ASLA, ASLA SRLG).

It’s late-ish on a Friday so I haven’t checked through the example in excruciating detail, and I kind of hope someone else is also checking, but if my understanding above is correct, I think maybe the change I’ve described gets us to the finish line.

In any case the fix to §4 (2.C) is enough for me to clear my DISCUSS, although I hope we can finish tuning up the example anyway of course.

Thanks,

—John