• United States
by Steve Taylor and Joanie Wexler

Tunneling and interworking over MPLS and IP

Oct 02, 20032 mins

* Alliance approves TDM-MPLS spec

Much work is afoot to port existing Layer 2 services to converged Multi-protocol Label Switching and IP networks. In a nutshell, these efforts should eventually enable you to add new services at certain sites, which can intercommunicate with legacy technologies in other locations.

Last month, the MPLS/Frame Relay Alliance approved a TDM-over-MPLS implementation agreement (IA).  The specification outlines a method for carriers to offer private-line services alongside packet network services across a converged MPLS network. 

The IA will lead to the availability of converged services when supported in the provider-edge routers, multi-service edge switches and dedicated gateway equipment used in carrier networks, according to the alliance. The alliance says it is also working on Layer 2 service interworking over MPLS in the spirit of FRF.8 frame relay-to-ATM interworking, which has been available over ATM backbones for many years.

Meanwhile, Cisco is already offering its own Interworking over Any Transport over MPLS (AToM) set of capabilities in its router software. The technology feature allows the service providers that use its gear to tunnel Layer 2 services over their MPLS backbones and mix and match Layer 2 subscriber services at different sites. In addition, Interworking over Cisco Layer 2 Tunneling Protocol Version 3 (L2TPv3) enables the same capabilities over a native IP carrier backbone, Cisco says.

The Cisco capabilities are based on an emerging IEFT Draft called “L2VPN Interworking.”

Carriers that deploy Cisco interworking over AToM or over L2TPv3 should be able to accommodate the protocol you prefer to run at each site. So if this is something you are interested in, ask your carrier about it.