Re: inter-domain link recovery

[Roland Dobbins <rdobbins () cisco com>]

On Aug 15, 2007, at 12:07 AM, Chengchen Hu wrote:

> is it always possible for BGP to automatically find an alternative  
> path when failure occurs if exist one? If not, what may be the causes?

Barring implementation bugs or network misconfigurations, I've never  
experienced an operational problem with BGP4 (or OSPF or EIGRP or IS- 
IS or RIPv2, for that matter) converging correctly due to a flaw in  
the routing protocol, if that's the gist of the first question.   
There are many other factors external to the workings of the protocol  
itself which may affect routing convergence, of course; it really  
isn't practical to provide a meaningful answer to the second question  
in a reasonable amount of time, please see the previous reply.

The questions that you're asking essentially boil down to 'How does  
the Internet work?', or, even more fundamentally, 'How does routing  
work?'.  I would strongly suggest familiarizing oneself with the  
reference materials cited in the previous reply, as they provide a  
good introduction to the fundamentals of this topic.

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Roland Dobbins <rdobbins () cisco com> // 408.527.6376 voice

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