[j-nsp] l2circuit for ATM cells carrying IP/MPLS traffic

[Piotr Marecki]

----- Original Message ----- 
From: "Tomasz Szewczyk" <tomeks at man.poznan.pl>
To: <juniper-nsp at puck.nether.net>
Sent: Thursday, January 26, 2006 12:55 PM
Subject: [j-nsp] l2circuit for ATM cells carrying IP/MPLS traffic


> Is it possible to transmit "MPLS over ATM" traffic over l2circuit?
> On both PE (Juniper M5) routers atm-ccc-vc-mux encapsulation is used on
> ATM interfaces towards CE routers. The l2circuit connection is used to
> transmit ATM traffic from CE routers through MPLS network. The PE
> routers are connected with GE interfaces (MTU 4700).
>
> [CE router]---ATM----[PE router]--GE--[PE router]----ATM-----[CE router]
>
> This connection works only if on CE routers (cisco) IP traffic is
> transmitted but doesn't work if IP/MPLS is used on CE routers.
> I think the problem is caused by encapsulation used on CE routers.
> Unfortunately cell-relay mode on one of PE routers can not be used (what
> in my opinion should solve the problem).
> Is there any way to solve this problem without changing to cell-relay
> mode on PE routers?
>
> -- 
> Tomasz Szewczyk
>
> e-mail: tomeks at man.poznan.pl
>

First , i think we need little bit clarification here. By "MPLS over ATM" do 
you mean MPLS+IP encapsulation in
so-called "frame mode" where MPLS packets are nothing more than AAL5SNAP 
PDU's with 0x8847 ethertype ,
or you have CE routers ( presumably C vendor ) that are using cell mode ( 
where label is encapsulated in vp.vc fields).
In first case , there should be nothing wrong with that setup , e.g assuming 
that you have ATM PIC in AAL5 mode , MPLS and
IP packets shall be transported without problems over L2cuircuit  AAL5 SDU 
PWE mode( assuming that aal5snap encaps
is configured on CE , with VC-MUX , IP+MPLS won't work together on same vc). 
In second case , imho it wont work
without cell mode.

regards

Piotr Marecki