[Idr] draft-ietf-idr-aigp-00

["Ilya Varlashkin" <Ilya.Varlashkin at de.easynet.net>]

Hi,

I've read through draft-ietf-idr-aigp-00 and find the idea quite good.
In fact it was long on my wish-list since as necessary tool to optimise
routing within BGP confederation. There are couple concerns, however,
regarding details of proposed functionality.

First, section 4.1 sugests to evaluate AIGP before LOCAL-PREF.
Considering that AIGP is close in ist nature to IGP cost, it seems more
natural to evaluate it right where IGP cost is evaluated. One
possibility could be: if a route has AIGP attribute with value X, then
add X to IGP cost of the NEXT_HOP and use result as tie-breaker instead
of plain IGP cost. It should be noted that if BGP implementation has
knob to consider length of CONFED_SEQUENCE and it's turned on, then
length of CONFED_SEQUENCE will take precedence, so if operator wants to
use AIGP they should consider turning off CONFED_SEQUENCE length knob.

Second, section 3.3.1 explicitly forbids adding AIGP to routes learned
from outside of AS. From operational prospective this rips off most of
the benefits that AIGP could provide. If a route learned by two
confederation member-AS are then injected into third member-AS, it would
be benifical to choose best of them based on AIGP value but the draft
won't allow this. Seems like serious drawback.

Comments from authors on the above would be appreciated.

Kind regards,
iLya