Subject: [Srcomp] Section 3.1.2

From: Ron Bonica <[email-masked]>
Date: Mon, 23 Nov 2020 14:58:54 +0000

Folks,

Greg Mirsky and John Scudder both raised valid issues regarding Section 3.1.2.

John Scudder asks which is more expensive:

  *   Parsing a single extension header, with 20 fields, some of which are variable length
  *   Parsing two extension headers, each of which has 5 fixed length, fixed position fields

The answer is probably platform dependent. This suggests that our list of metrics (D.PRS and D.LKU) may be incomplete. This incompleteness may lead us to prefer solutions that perform less well.

The problem is exaggerated by the SRH tag, flag and TLV field. It appears that these need to be checked, even when the next hop is resolved by a uSID. (Darren, do I have this part right? Is it documented anywhere?)

I can see two ways to fix this problem:

  *   Spend lots of time specifying a benchmarking procedure, as Greg Mirsky recommends
  *   Limit metrics to D.PRS

Given my advanced age, I think that we only have time for the latter 😉

                                                                        Ron

Juniper Business Use Only