[c-nsp] iBGP not propogating route to 0/8

[Tassos Chatzithomaoglou]

I think it has to do with the default route "confusion"...

1) You can use "default-information originate" under the bgp process and trick bgp that this is the default route (i guess only 
the network part is checked). The network is shown as "0.0.0.0/8" which means that the router doesn't consider /8 to be the 
default length of 0.0.0.0, like in 3.0.0.0.

R1>sh ip bgp
BGP table version is 20, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
               r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

    Network          Next Hop            Metric LocPrf Weight Path
*>i0.0.0.0/8        1.1.1.2                  0    500      0 i
*>i3.0.0.0          1.1.1.2                  0    500      0 i


2) You can use "network 0.0.0.0 mask 255.0.0.0 route-map static-to-bgp" under bgp and force its advertisement.

Method 1 requires redistribution of the route, method 2 requires route to be present in IGP/static.
In your case, you have both ;)

--
Tassos


David Sinn wrote on 16/5/2008 7:06 μμ:
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> On May 15, 2008, at 2:31 PM, Justin Shore wrote:
> 
>> I can't think of any reason why this prefix wouldn't be advertised.   
>> Any
>> ideas?  I noticed it today because I have customers trying to hit 0/8
>> IPs (0.4.24.200 for example) that my egress ACLs are catching.
> 
> This is due to how Cisco treats martian networks per their  
> interpretation (or real meaning) of RFC 1812.  Since the following are  
> martians, to cover the "Should not" route part of 5.3.7, they won't  
> install them in the route table.
> 
> 0.0.0.0/8
> 127.0.0.0/8
> 128.0.0.0/16
> 181.255.0.0/16
> 192.0.0.0/24
> 233.255.255.0/24
> 240.0.0.0/4
> 
> I've only personally tested 240.0.0.0/4 and it will not install in the  
> route table.  I've also not tried to figure out what more or less  
> specific routes you could try and install to cover these blocks.
> 
> David
> 
> 
>> Thanks
>>  Justin
>>
>>
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-- 
***************************************
         Tassos Chatzithomaoglou
Network Design & Development Department
              FORTHnet S.A.
          <achatz at forthnet.gr>
***************************************