nanog mailing list archives
Re: "Neighbor maximum-prefix" option on routers
From: Alexander Koch <efraim () clues de>
Date: Mon, 20 Nov 2006 09:53:06 +0100
On Mon, 20 November 2006 09:03:17 +0100, Mikael Abrahamsson wrote: [..]
Having both max-prefix and route-map and prefix-list makes for good engineering over time.
Ain't that a bit over- engineered? If you have a prefix list (presumably to a customer) do you want to seriously shutdown the session when he sends you random prefixes because it is easy to break when you are new to it? Would create unneeded tickets I'd say. Prefix lists (exact match) with no max-prefix (as those are then rejected anyway) work fine here... But then, I was not wondering what you or Joe do as you know what you do and why for sure. ;-) But I would really be interested in how smaller ISPs do it. Given how many ppl still use prefix-lists outbound (and leak whatever is best in their routing table when a customer is not announcing a prefix to them) I wonder what can be done. Let alone the random appearance of /24 announcements out of a /20 or so, and when you check and ask and insist on it you find out there is a redistribute statement and they just added a /24 internally... Back on track, what is max-prefix good for anything but peers? A transit session is pretty much 'all' already, and customer are filtered anyway? (coming back to the initial question in this thread) Let alone how many operators monitor sessions down for prefixes -- some ISPs deserve to be depxxxxx when they find out after one month (been there, more than once) the sessions are down, and they ask you why those are down, cutting and pasting the 'Idle (pfxcount)' in their email even. That is my personal view though. So max-prefix is good for peers, maybe for customers, hardly for transit sessions, and whenever you do it, MONITOR IT ;)=) A three- line perl / sh script on top of your syslog or during logrotate or so is advised if only that. Alexander
Current thread:
- "Neighbor maximum-prefix" option on routers Ricardo V. Oliveira (Nov 19)
- Re: "Neighbor maximum-prefix" option on routers Jay Hennigan (Nov 19)
- Re: "Neighbor maximum-prefix" option on routers Alexander Koch (Nov 19)
- Re: "Neighbor maximum-prefix" option on routers Mikael Abrahamsson (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Joe Abley (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Alexander Koch (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Daniele Arena (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Mikael Abrahamsson (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Niels Bakker (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Jeff Aitken (Nov 20)
- Re: "Neighbor maximum-prefix" option on routers Alexander Koch (Nov 19)
- Re: "Neighbor maximum-prefix" option on routers Jay Hennigan (Nov 19)
- <Possible follow-ups>
- Re: "Neighbor maximum-prefix" option on routers Scott Weeks (Nov 19)