From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Thu Aug 23 2007 - 13:34:39 ART
A lot of large providers run IS-IS as their IGP, BGP at the edge,
and then MPLS in the core. Running MPLS not only enables advanced services
like traffic engineering and L2/L3 VPNs, it also removes the requirement of
transit devices having to carry the full public BGP table. It works this
way because the MPLS enabled routers don't need to know what the final
destination of a packet is, only what the exit point is.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Gregory Gombas
> Sent: Thursday, August 23, 2007 10:37 AM
> To: Cisco certification
> Subject: Question for you ISP guys
>
> For those of you with ISP experience, can you tell me what routing
> protocols do service providers typicall run within their AS?
>
> Do you have every single router running BGP? I can't imagine
> redistributing 225k+
> routes into an IGP, so how do you pass these routes withing your AS?
>
> If you are using iBGP what are you using to transmit next hop
> information (as iBGP does not normally update the next hop of the
> external AS)?
>
> Can someone point me to some documentation showing typical ISP routing
> design?
>
> Thanks,
> Greg
>
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