Re: BGP LABEL LSP

Anybody get this ? ANy thoughts on this ?

On Mon, Dec 10, 2012 at 10:41 PM, Routing Freak <routingfreak_at_gmail.com>wrote:

> Hi
>
> I have a topology like this
>
> ____________ibgp______________
>
> R5------------------R1-------------------R2-----------------------R3
> ibgp ebgp ebgp
>
>
> R1 and R3 are running iBGP in AS 100 and R1 and R2 are running eBGP with
> R2 in AS 200 and respectively R2 and R3 are eBGP neighbors.
>
> There is no physical connection between R1 and R3 . There is an iBGP peer
> between R1 and R3 via R2 which is a eBGP peer with both R1 and R3
>
> Now R1 is a RR and R5 and R3 are clients
>
> MPLS is enabled between R1 and R2 and R2 and R3. But there is no LDP or
> RSVP enabled on those interfaces.I have just enabled the forwarding place
> saying that this interface can receive labelled packets.
>
> R3 is learning R5's routes via R1's iBGP connection with a next hop as R5.
>
> R5's loopback is advertised as ebGP route to R2 from R1 and it is passed
> to R3 from R2 as eBGP route.
>
> Now when R1 is sending as Ipv4 Unicast routes with Labels on it. ( with
> Send label option ) to R2.
>
> R2 is also having the send label in the eBGP peering with R3 .
>
> So now for R3 to reach R5s loopback there it should use a label sent from
> eBGP neighbor R2.
>
> So now here is the problem part. I dont have a label for the prefixes ( ie
> R5 advertised prefixes ) and i only have the next hop which is R5 loopback
> label ( ie advertised by R2 to R3 ) .
>
> So when R3 is sending traffic to R5's prefixes, will it use the BGP label
> to R2 and R2 will use the BGP label to reach R1 and then R1 will strip the
> label and do a normal routing lookup to send traffic to R5
>
> Will BGP label forms an LSP ?. When a next hop in a BGP table is again
> learned by BGP, will it use the BGP label to send the traffic ?
>
> Without the prefix label , will only the next hop BGP label will work to
> form LSP ?

Blogs and organic groups at http://www.ccie.net
Received on Tue Dec 11 2012 - 07:30:55 ART