The MPLS-OPS Archive

[Aamer Akhter <aakhter@cisco.com>]

On Oct 19, 2004, at 1:16 PM, vishwanathan mv wrote:

> Mine was a more design based question.
> >
> >Lets assume that I decided not go in for CR-LDP but to go with only
> >LDP.  In this case, the label assignment by LDP will be either
> solicited
> >or unsolicited downstream.  In either case, the initial route it takes
> >from the source to the destionation (before LDP can initiate the label
> >assignment downstream) is the default IP route i.e. SPF specified in
> each
> >of the routers (from source to destination).  This implies that we
> lost
> >out on MPLS's ability to route data through a LSP.  Am i making a
> mistake
> >in this observation?

Your observation is correct as far as the LSP following the regular IP 
path. The data (let's say l2vpn or l3vpn traffic, or any traffic) is 
still routed thru a LSP.

Regardless, RSVP-TE and CR-LDP is how you could create a LSP that does 
not follow the IP path.

thanks.

> >
> >Thanks
>
>
> Aamer Akhter <aakhter@cisco.com> wrote:
>
>  On Oct 18, 2004, at 8:22 AM, vishwanathan mv wrote:
>
> > The purpose of using LDP is to automate the label distribution.  But
>  > the basic route that the packets take initially is the default ip
> > routes.  Is this what we wanted?
>
> depends on how LDP is used. as you've said, LDP is for label
>  distribution- how those labels are used is a different matter. For
>  example in the case of martini you have a case of network
>  ingress-egress. But if your point is that regular use of LDP relies on
> regular IP hop-by-hop forwarding that is a true and was the intention.
>
>
> >   Haven't we lost out on our power to use MPLS (design our own 
> routes)
>  > - the reason for which it was designed?  I know that using CR-LDP 
> one
>  > can get over this.
>
> RSVP-TE is one way to get around the hop-by-hop model.
>
> hope this helps
>
> >  
> > Thanks in advance.
> >
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>
> -- 
> Aamer Akhter / aa@cisco.com
> NSITE cisco Systems
>
>
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-- 
Aamer Akhter / aa@cisco.com
NSITE cisco Systems


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