[c-nsp] AS override

[Oliver Boehmer (oboehmer)]

Danny,

Re-writing AS paths is a dangerous thing (as you will take BGP's only
loop prevention mechanism away), so we are not allowing it except within
the MPLS-VPN setup using as-override. 

	oli

Danny Vernals <mailto:danny.vernals at gmail.com> wrote on Wednesday,
October 05, 2005 4:16 PM:

> Hi Oliver,
> 
> I just had concerns over routing table security / integrity but now I
> think about it the same issues arise with override as with
> allowas-in.  I think I can mitigate against these issues with careful
> design.   
> 
> Ideally I'd only like to re-write the ASN  for  certain prefixes that
> are matched in a route map matching on community / prefix list etc. 
> However as far as I'm aware this is not possible?  
> 
> Thanks for the reply
> 
> Danny
> 
> 
> On 10/5/05, Oliver Boehmer (oboehmer) <oboehmer at cisco.com> wrote:
> 
> 
> 	>
> 	> Do you know of a way to configure AS override functionality
not in
> 	a > VRF? I need to allow prefixes oringated from an AS to be
> 	advertised > back into it. Ideally I'd like to avoid using
> 	allowas-in. I have > admin control of both of the connected
AS's.
> 
> 	as-override is, as you have observed, only available in ipv4-VRF
> 	context. Why do you want to avoid allowas-in?
> 
> 	        oli