January 30, 2003

By Jenny Carless, News@Cisco

Sprint recently announced that it is offering its customers new IP services based on Cisco Systems' Layer 2 Tunneling Protocol version 3 (L2TPv3), a new protocol that enables Layer 2 (L2) transport over a packet-based core. L2TPv3 was pioneered by Cisco in collaboration with Sprint. News@Cisco asked Barry Tishgart, director of product management for Sprint Business, and Sangeeta Anand, vice president of product management for Cisco's Internet Technologies Division, to discuss this technology and the services and business benefits it offers.

What is L2TPv3, and why is it important?

Sangeeta Anand: Cisco's Layer 2 Tunneling Protocol version 3 (L2TPv3) is a new capability that we've incorporated into Cisco. IOS Software. Essentially, it tunnels Layer 2 frames across an IP-based packet network in a way that is as transparent as possible to both end-users and applications.

It's an important step forward because it allows Layer 2 data services to be provided over an IP backbone. So service providers can now deliver traditional services such as Frame Relay, ATM, Ethernet, and Leased Line over their packet-based core. Another enabled service can be described as "bridging" over the packet-based core without having to use traditional bridging mechanisms.

Multinational corporations and other customers benefit because they can have an L2TPv3-based Frame Relay service for less cost than a similar service provided from a traditional Frame Relay network. This is because of the inherently lower operational and investment costs of a multi-service IP-based network. In addition, L2TPv3 enables our customers to expand their global reach by utilizing their existing IP infrastructures to connect geographically disparate networks.

Why did Sprint decide to deploy L2TPv3?

Barry Tishgart: At Sprint, we're always looking for ways to better meet our customers' needs while leveraging our existing network assets, and L2TPv3 allows us to do just that. In fact, by deploying L2TPv3 across our global IP backbone, we were able to roll out three new high-performance, cost-effective data networking services in a matter of months with no additional capital investment. It's really a win-win solution for us and our customers.

What are the new services L2TPv3 has enabled you to offer?

Barry Tishgart: Our new L2TPv3-enabled services include SprintLink Frame Relay, SprintLink Packet Private Line and SprintLink Virtual LAN Service. In a nutshell, all three of these services are about helping our customers meet their data networking needs in the most flexible, reliable, secure and cost-effective manner possible. They each offer innovative alternatives to traditional WAN connectivity solutions that, when combined with the rest of our product portfolio, allow us to construct robust, requirements-based solutions for our customers.

Can you describe how this new protocol came about and the technology behind it?

Sangeeta Anand: Cisco pioneered the L2TPv3 protocol in order to transport Layer 2 access over native IP backbones. With IP networks that support multiple services, service providers can deliver more and more of their services from a single network infrastructure, thereby lowering the cost of providing those services and gaining an important competitive edge.

The protocol is based on optimized extensions to the underlying L2TP standard and includes signaling enhancements, a new encapsulation header, and a protocol identifier to support the end-to-end transportation of multiple Layer 2 protocols. It incorporates support for Frame Relay, ATM, HDLC, PPP, and Ethernet and can also provision transit tunnels across multiple MPLS and IP packet core networks.

There are two core capabilities that enable L2TPv3. The first is IP encapsulation/de-capsulation: L2TPv3 gives Sprint's Cisco routers the ability to take Layer 2 traffic at the edge and encapsulate it (add an IP header) and traverse Sprint's IP core, SprintLink. Conversely, at the egress point of the IP core, the IP header is removed, or de-capsulated, and the traffic returns to its original Layer 2 state. This couldn't be done before.

The second core capability is tunneling. L2TPv3 enables the creation of tunnels across SprintLink. These tunnels can be mapped to Layer 2 sub-interfaces, effectively creating permanent virtual circuits across the SprintLink core. These tunnels "lock" traffic between sub-interfaces on SprintLink ports.

The L2TPv3 protocol is just one part of Cisco's new Unified VPN Suite; how do you see this new suite fitting in to the market?

Sangeeta Anand: Cisco's Unified VPN Suite is the industry's most complete set of Layer 2 and Layer 3 VPN technologies. Integrated across Cisco's core and access platform portfolio, it supports the largest common set of IP services and provisioning capabilities.

The Unified VPN Suite delivers new VPN technology for IP and MPLS backbone networks, and that's good news for everyone. It enables service providers to expand their reach, introduce new IP service offerings and transport existing access traffic cost effectively over their packet backbones. For enterprises, it means significantly improved choices and flexibility.

Jenny Carless is a freelance writer based in Santa Cruz, CA.