Juniper: The VPLS Odd-Ball?

PARIS -- A demonstration of MPLS interoperability at the MPLS World Congress ’05 conference here has illustrated a couple of key points about Virtual Private LAN Service, the multi-point Ethernet service supported by Multiprotocol Label Switching (MPLS) (see MPLS Bigwigs Get Edgy).

First, significant progress has been made in solving scaleability and manageability issues that have held back VPLS deployments until now.

Second, everything isn't quite sweetness and light, notably because Juniper Networks Inc. (Nasdaq: JNPR) is persevering with promoting an alternative (and some would say better) version of VPLS that's imcompatible with everybody else's.

The interoperability demo was organized by the MPLS/Frame Relay Alliance and facilitated by European Advanced Networking Test Center AG (EANTC) (Light Reading’s testing partner).

Test equipment from Agilent Technologies Inc. (NYSE: A) and Ixia (Nasdaq: XXIA) was used (see Agilent Touts Multiservice Testing & Deal and Vendors to Demo MPLS Interoperability).

The demo indicates a fair degree of interoperability among vendors that have implemented hierarchical VPLS -- a new(ish) version of VPLS that sidesteps the issue of creating too many MPLS label-switched paths if a fully-meshed network is extended towards customer sites.

Hierarchical VPLS has a fully meshed core, which is linked to customer sites via pseudowires (point-to-point connections over MPLS infrastructure).

A total of 10 vendors participated in the interoperability demo, which spanned basic traffic engineering signaling, various pseudowire technologies, and management tools in addition to hierarchical VPLS. The gear that was tested for hierarchical VPLS interoperability was:

• Alcatel's (NYSE: ALA; Paris: CGEP:PA) 1662 PRS and 7750 SR
• MRV Communications Inc.'s (Nasdaq: MRVC) OSM
• Native Networks Ltd.’s EMX3706
• RAD Data Communications Ltd.’s ETX-510
• Riverstone Networks Inc.'s (OTC: RSTN.PK) 15008 and RS8600

Cisco Systems Inc. (Nasdaq: CSCO) and Ciena Corp. (Nasdaq: CIEN) also participated in the demo, but didn’t field equipment supporting hierarchical VPLS.

Although the demo shows that hierarchical VPLS gear from different vendors interoperates in a small configuration, there are still some rough edges.

For instance, equipment extending VPLS towards customers often doesn’t support OSPF (Open Shortest Path First), so devices have to be configured manually. Also, vendors had implemented different versions of label switching path “ping” and “traceroute,” which meant that interoperability of operations, administration, and management (OAM) functions couldn’t be achieved in all cases.

Among notable absences from the demo is Juniper. Its version of VPLS is based on BGP (Border Gateway Protocol) rather than LDP (Label Distribution Protocol). It maintains that its BGP version of VPLS doesn’t suffer the scaleability issues of LDP-based VPLS, and thus doesn’t need a hierarchical structure.

The issue of which version is best is “a dead debate. Only Juniper is trying to revive it,” says Marc Lasserre, Riverstone’s chief scientist, noting that the proposal needs support from at least three vendors to become an Internet Engineering Task Force (IETF) RFC (request for comment).

Sources say that Juniper’s BGP version of VPLS is better technically than the LDP version, and that Juniper has persevered with it because of encouragement from some of its carrier customers. Although Juniper’s equipment wouldn’t interoperate with LDP-based VPLS equipment in the same cloud, carriers can connect Juniper VPLS clouds to LDP VPLS clouds, notes Hector Avalos, Juniper’s technical director of product and technology, EMEA.

Another notable absentee from the interoperability demo was Nortel Networks Ltd. (NYSE/Toronto: NT), which only announced VPLS equipment this week, and has yet to introduce hierarchical VPLS (see Nortel Adds to Multiservice Portfolio).

— Peter Heywood, Founding Editor, Light Reading