useful bgp example

Dan White dwhite at olp.net
Wed May 19 13:58:38 CDT 2010


On 19/05/10 13:37 -0500, Jeff Harper wrote:
>> -----Original Message-----
>> From: Jared Mauch [mailto:jared at puck.nether.net]
>> Sent: Wednesday, May 19, 2010 1:29 PM
>> To: Jeff Harper
>> Cc: Deric Kwok; nanog at 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

You should be using 192.168.2.0 for documented examples,or at least private
space. Configs like this tend to get cut and pasted into routers and get
changed only when they don't work.

I just had to change a router config a couple of months ago that a consult
had set up using 11.0.0.0/24 and 12.0.0.0/24, for point to point links.

-- 
Dan White




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