[quagga-users 11401] Re: Puzzled with filters.

Nick Hilliard nick at inex.ie
Wed Mar 10 22:19:02 GMT 2010


On 10/03/2010 21:32, Xavier Beaudouin wrote:
> The main problem is that I have 24 routes from 193.xxx.xxx.5 that should
> be also redistributed into 193.xxx.xxx.1, but I got only 4 routes : the
> default gateway and the 3 subnet defined in network stuff.
> 
> Now when I do sh ip bgp prefix-list igppfx, I got the corrects routes
> that should be announced into 193.xxx.xxx.1...

This is a FAQ.  In fact, an EFAQ (an Extremely Frequently Asked Question).

You have 3 routers: 193.xxx.xxx.1, 193.xxx.xxx.3 and 193.xxx.xxx.5.  You
want to exchange prefixes between .1 and .5, where .3 is in the middle.
iBGP will not do this for you by default;  this is to avoid routing loops:

> http://www.ripe.net/ripe/meetings/ripe-42/presentations/ripe42-eof-bgp/sld006.html

To propagate prefixes between the .1 and .5, you either need to set .3 up
as a route reflector, or else set up full mesh BGP so that .1 talks
directly to .5.  As you appear to have a proper IGP setup, the latter
shouldn't be a problem.

Nick


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