[j-nsp] as-path rewrite

[Sorin CONSTANTINESCU]

On 9/27/05, Pedro Roque Marques <roque at juniper.net> wrote:
> Sorin CONSTANTINESCU wrote:
> > Hi, all.
> >
> > I have the following topology:
> >
> > AS1 - AS99 (L3 Mpls VPN) - AS2 - AS99 - INTERNET
> >
> > My customer (AS2 - public AS Number) buys from the company i work for
> > 2 services:
> >
> > 1) Internet Access
> > 2) VPN between his location, and AS1 (also public AS Number).
> >
> > The problem i have is that when i receive a prefix originated by AS1
> > on the Internet Transit BGP session, the AS-PATH is: 1 99 2 . Our
> > network is a mixture of Juniper and Cisco routers. I used "allowas-in"
> > on the neighbor to the customer, but the Juniper routers won't import
> > this prefix throughout the network. I know i can use
> >
> > Has anyone ever ran into this problem? As far as i see it, i have the
> > following options:
> >
> > - use private "local-as" for the BGP sessions between AS99 and AS1/AS2
> > for the MPLS VPN BGP sessions (haven't tested this one so far)
> > - ask the customer to configure EBGP Multihop between AS1 and AS2, so
> > that my own AS won't be in the AS-PATH
> >
> > I wish i could AS-PATH rewrite :))
>
> There is another option, which is pass the iBGP information of your
> customer transparently across the VPN network. i.e. the routes on the
> customer side will not see the AS(es) that are used on the VPN network.
>
> On juniper boxes you can do this by configuring a VRF such that:
>
> routing-instance {
>     customer {
>         routing-options autonomous-system <customer-as> independent-domain;
>         protocols {
>             bgp {
>                 group pe-ce {
>                     type internal;
>                     neighbor <x.x.x.x>;
>                 }
>             }
>         }
>     }
> }
>
> This will instruct the PE to transport the customer network BGP
> attributes transparently over the VPN infraestructure. The protocol
> extension is documented in draft-marques-l3vpn-ibgp-01.

Thanks very much! It's indeed a very useful feature.

>
>   Pedro.
>

Regards,
--
Sorin CONSTANTINESCU
Cisco CCNP / JNCIA #845
consta at gmail.com