inline
^ ^
==============ooo====(.)v(.)====ooo=====
Javier Antich Romaguera
Network Consultant
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> -----Mensaje original-----
> De: Bala Subrahmanyam Venkata [SMTP:bsubrahm@doradosoftware.com]
> Enviado el: viernes 22 de junio de 2001 18:33
> Para: Javier Antich
> CC: juniper-nsp@puck.nether.net
> Asunto: RE: [j-nsp] Differentiating MPLS VPN
>
> Javier-
>
> Thanx. Its always nice to see a quick reply :-) I got some
> questions...please see them inline
>
>
> > > This question was actually posted by me even in the MPLS OPs list. I
> > > wanted
> > > to know Juniper's stand on this.
> > >
> > > Suppose if I have an MPLS core network with 4 PEs (PE1, PE2,
> > PE3 and PE4).
> > > Say I also have two LSPs between PE1 and PE2 - one with a
> > bigger bandwidth
> > > and the other one with a less bw. If I group these two PEs (PE1 and
> PE2)
> > > in
> > > a 2547bis VPN, can I steer the VPN traffic into one of those two LSPs
> I
> > > have
> > > between the PEs ? If so how ?
> > >
> > [Javier Antich]
> > First of all I would say that there are no "real" bandwidth
> > reservations for LSPs unless you police at the entry point.
>
>
> [Bala S Venkata]--->
> So what happens when I create an LSP using the "label-switched-path"
> statement under the "[edit protocols mpls]" hierarchy in a Juniper device
> ?
> I can specify a bandwidth for the LSP (in addition to my primpary and
> secondary named paths) correct? What is this bandwidth ?
[Javier Antich] Is a scalar value that is decremented at each hop
of the LSP or RSVP-TE session in the admission process of the LSP
> And I assume that when you say "police at the entry point" you are talking
> about schemes like rate limiting or access control ? How can this
> guarantee
> a bandwidth for an LSP ?
[Javier Antich] I mean that the current implementations of Traffic
Engineering using
RSVP-TE only make reservations in the control plane, not in the
forwarding plane. That is, you can make a reservation of 1 Mbps for one LSP
but there is no implicit mechanism that prevents you from sending 10 Mbps
through the LSP unless you limit it at the ingress point. The only way to
guarantee bandwitdh is limiting the resources others can use.
> >But let us
> > suppose that we have, between PE1 and PE2 two different LSPs, one
> default,
> > probably generated by LDP and other one, probably created by RSVP-TE. I
> am
> > not sure if what I am saying works, because I have not tested it, but I
> > would try to do:
> > Create the RSVP-TE Traffic Engineered LSP between secondary
> > loopback addresses (no loopback interfaces, as Juniper supports
> > only one) in
> > PE1 and PE2.
>
>
> [Bala S Venkata]--->
> I assume you are talking about the "from" and "to" statements in the
> "[edit
> protocols mpls label-switched-path lsp-path-name]" hierarchy, is that
> right
> ?
>
[Javier Antich] Yes.
> > In PE1 create a policy statement in the import and export
> > commands in the vrf configuration so that for routes with the
> appropriate
> > route-targets and whose next-hop is PE2 (from next-hop PE2) change the
> > next-hop to the secondary loopback address of PE2 (set next-hop ...).
> This
> > way traffic belonging to that VPN and going to PE2 would use the
> > traffic-engineered path (I hope so!).
>
>
> [Bala S Venkata]--->
> Again referring to JunOS specifically, this next hop statement should go
> in
> my "policy-satement <policyname> term <term> then" hierarchy, correct ?
>
>
[Javier Antich] Yes, the policy-statement that you will use in the
import <> command in the VPN routing instance.
> > However, probably this does not scale too much. Well, maybe even
> > does not work (can someone test it?).
> > > Also what happens if PE3 and PE4 now decide to be part of that
> > VPN ? Do I
> > > need to do the same between all the PEs if I want to steer the
> > VPN traffic
> > > between them into one of the LSPs between them ??
> > >
> > [Javier Antich]
> > And what if there are lots of VPNs?? Probably it is not a good idea
> > to have per-VPN LSPs between PEs.
>
>
> [Bala S Venkata]--->
> How else do you think a Service Provider can offer "differentiated" VPN ?
> Looke like he/she can use the LSP for that since LSPs seem to have that
> level of differentiation (in terms of say bandwidth..)
[Javier Antich] No they do not have it. In terms of QoS, packets
are not treated according to the LSP they belong to but according to the CoS
field they carry (exp bits). Maybe new MPLS implementations will do it.
> Thanx for your time !
>
> bala
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