OSPF to BGP Redistribution Max Prefixes issue

[marioderosa2008]

Hi,

we have a BGP peer with our ISP and they have a maximum number of prefixes threshold which we seem to breach causing them to shut down the BGP session.

Now we have configured aggregate addresses so we actually only send our ISP 4 prefixes however upon reboot of the router it appears that all prefixes are initially sent as the BGP process terminates with the Max Prefix Limit Reached error code shortly after OSPF converges.

Is there a way to stop this from happening?

Is this a known bug? We are running image asr1001-universalk9.03.04.02.S.151-3.S2.bin

Thanks

Mario                  

[de1denta]

Hi,

A simple way to prevent this is to filter your outbound advertisements using a prefix-list or route-map to only permit the aggregate address.

[marioderosa2008]

Hi,

we use a prefix list & route-map which only permits the aggregate routes. But it seems on boot up of the router ALL prefixes get leaked.

Once the ISP enables the BGP session again, only the 4 aggregate addresses are advertised.

I think its a bug,.

Mario

[daniel.dib]

Are you using summary-only? Otherwise you will send both the aggregate and all the more specific routes. Did you only see this issue at reboot?

Daniel Dib
CCIE #37149

[marioderosa2008]

HI Daniel,

not sure what you mean by summary only.

We have a prefix list permitting 4 x /22 subnets. Then we advertise those networks in BGP using the aggregate address commands.

Yes we only see this happening on boot up. I guess the same may happen if we shut and no shut the interface too. Not sure. It seems that all prefixes get leaked which causes the ISP to shut down BGP session.

Once the ISP re-enables BGP, they only receive our 4 prefixes.

Mario