nanog mailing list archives

RE: useful bgp example


From: Vincent C Jones <v.jones () networkingunlimited com>
Date: Wed, 19 May 2010 15:04:15 -0400



On Wed, 2010-05-19 at 13:37 -0500, Jeff Harper wrote:
From: Jared Mauch [mailto:jared () puck nether net]
Sent: Wednesday, May 19, 2010 1:29 PM
To: Jeff Harper
Cc: Deric Kwok; nanog () nanog org
Subject: Re: useful bgp example

Nice, but you don't show it as-path filtering your transits out.  I
frequently see people take something learned from transit A and
sending
it to transit B, and if it happens to be the backup path in-use for
your customer, your transits will accept it and likely pick you as
best-path and hairpin through your network.

- Jared

Yeah, I left out the actual prefix-list contents, in hindsight I should
have added it, so here it is. Also, a typo in the network statement,
lol.

network 1.1.1.0 mask 255.255.0.0

ip prefix-list NETZ description The networks we advertise via BGP
ip prefix-list NETZ seq 10 permit 1.1.1.0/16
ip prefix-list NETZ seq 1000 deny 0.0.0.0/0 le 32

FYI: It's got to be either 1.1.1.0/24 or 1.1.0.0/16. And there is plenty
more that belongs in an appropriate setup for a realistic usage
scenario. This is why we are all advising the OP to get some
knowledgeable help. 

Vince
-- 
Vincent C. Jones
Networking Unlimited, Inc.
Phone: +1 201 568-7810
V.Jones () NetworkingUnlimited com



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