Routing-Bits

I am currently attending a 2-day Cisco PVT seminar for Service Providers, where the Cisco boys are sharing some of the new and upcoming technologies and hardware on the roadmap from 2010 onwards.

Cisco Systems are where they are today because of their groundbreaking innovation.
After seeing some of the specifics and configuration, OTV really seems impressive.

What is OTV (Overlay Transport Virtualization)?

A critical network design requirement for deployment of distributed virtualization and cluster technologies between separate date centers are having all servers in the same Layer 2 VLAN. Meeting this requirement means extending VLANs over Layer 3 networks, but current data centre interconnect (DCI) solutions introduce operational and resiliency challenges.

To address these challenges, Cisco developed a new DCI solution, called Overlay Transport Virtualization (OTV).

OTV can be thought of as MAC-address routing, in which destinations are MAC addresses, and next hops are IP addresses. OTV simply maps MAC address destinations to IP next hops that are reachable through the network cloud. Traffic destined for a particular MAC address is encapsulated in IP and carried through the IP cloud (typically the backbone) to its MAC-address routing next hop.

The greatest part, implementing OTV does not require new or complex protocols or a network redesign; it simply overlays over the existing IP network. No MPLS or any tedious tunnel technologies are required, only IP.

OTV does not rely on traffic flooding to propagate reachability information for MAC addresses. Instead OTV does it in-house. Flooding of unknown traffic is suppressed by OTV. Address Resolution Protocol (ARP) traffic is forwarded only in a controlled manner, and Spanning tree Bridge Protocol Data Units (BPDUs) are not forwarded. Instead the MAC address locations are distributed dynamically between the OTV edge devices. Which is really great in preserving most of the scalability, resiliency, multipathing, and failure-isolation characteristics of a Layer 3 network.

It is recommended to use Multicast in the core transit, (although not required), to really see the true efficiency of OTV.With Multicast enabled unnecessary header duplication of packets are avoided, thus optimizing the encapsulated MAC flows between sites.

The configuration to achieve all of this is only a few lines. A truly powerful technology which is extremely simple to implement.

From what was said today, the launch is scheduled for April. And OTV will initially be available only on the Nexus 7000. But the ASR 1k and Cisco-6500 are on the roadmap.

It seems that although this is based on standards technologies, OTV will initially be exclusive to the networking gods Cisco. Cisco has filed patents for this ground breaking technology, but also claims they will submit the IETF drafts by the end of 2010. Will have to wait and see.