BGP Default Route

Lupi, Guy Guy.Lupi at eurekaggn.com
Sat Sep 14 18:18:15 UTC 2002


I was wondering how people tend to generate default routes to customers
running bgp.  Is it from the aggregation router that customers are directly
connected to, or from one or more core/border routers?  If one is using a
default route to null 0 on aggregation routers that maintain a full bgp
table (assuming that the full table represents all destinations on the
Internet, and therefore dumping traffic to a destination not in that table),
and assuming Cisco routers using the default-information originate command,
then as long as the router is up and it's bgp sessions with peers are up, it
is going to send the default route regardless of it's ability to forward
traffic to external destinations.  The same goes for the default route
announced by a core/border router, if it's default is generated by the null
route.  Is an assumption made that with a good network design, no router
will every be without valid routing information, with the exception of a
complete failure of the router? 

Guy H. Lupi





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