Robert, Rafal,
Can we summarize this thread by saying that abstract-nh has the following
goals (listed in order of importance) :
1. Rapid deactivation of all routes that resolve through an ANH when the ANH
is withdrawn
2. Reduction in churn when one or more (but not all) of the BGP sessions
that map to an ANH terminates
3. Reduction the number of routes advertised to the RR
These benefits are not without cost. Because fewer routes are advertised to the
RR, some information is lost.
Do I have this much right?
If Rafal points out this issue in the draft, might network operators be able to
make informed decisions regarding whether the costs outweigh the benefits in
their network?
Ron
From: GROW <[email protected]> On Behalf Of Robert Raszuk
Sent: Monday, March 4, 2019 4:19 PM
To: Rafal Jan Szarecki <[email protected]>
Cc: [email protected]; Natrajan Venkataraman <[email protected]>
Subject: Re: [GROW] Review request for
draft-szarecki-grow-abstract-nh-scaleout-peering-00
[RJS] What if eBGP goes down while BFD stays up, for whatever reason? IMO
tracking BGP session state is correct think to do.
Not a problem :) Add as many as you like additional tracking rules.
Example:
event syslog pattern “.*%BGP-5-ADJCHANGE:neighbor x.x.x.x DOWN”
[RJS] It is matter of opinion. I see drawback of “READ_ONLY” – it delays
propagation of (potentially) large data set --> make entire BGP convergence
slower. W/ technique described in draft I propagate large data set ASAP but
prevent other speaker from use it, until ANH become active in IGP.
The main point of READ_ONLY mode is to reduce control plane churn when paths
learned first would not keep the "best path" status upon other peers coming up
and bringing better paths on the given ASBR.
Besides it matters only during the initial session bring-up.. As you have many
peers giving you similar set of routes anyway it really does not affect your
reachability at all.
Thx,
R.
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