Summary: New voices gather in the Packet Pushers virtual boardroom for a discussion of Cisco's layer 2 extension technology, Overlay Transport Virtualization (OTV). Ethan Banks hosts a recording of about two hours worth of content about OTV; this show is the second hour (well, almost another hour). Joining Ethan are first-time guests Jamie Caesar, Colby Glass and Ken Matlock. Jamie, Colby and Ken have all done real-world OTV deployments. Among the three, both the Cisco Nexus 7000 platform and ASR1000 platforms are represented. What's OTV and why do you care? OTV is a layer 2 extension technology aka data center interconnect (DCI). By L2 extension, we mean extending a VLAN from one data center into a different data center, when those data centers are separated by a layer 3 boundary. OTV is a tunneling overlay that encapsulates Ethernet frames so that they can cross the layer 3 area separating the 2 data centers. While simple in concept and fairly simple to deploy, OTV is rather complex behind the scenes, which is why this was a nearly 2 hour discussion instead of 20 minute one. Here in part two, we cover the following high level topics. Redundancy of OTV edge devices. What is traffic tromboning? How do you minimize it? Managing ARP & CAM timeouts to prevent the overlay from becoming a black hole, since OTV doesn't flood unknown unicasts. Coping with MTU sizes and the overhead added by OTV encapsulation. Designing your IGP to avoid forming a routing adjacency across the overlay, which would probably result in suboptimal forwarding paths forming. Licensing. Preparing your network to add OTV. CLI configuration of OTV. Useful OTV "show" commands. Our favorite OTV documentation. LINKS Cisco OTV Home Page Cisco OTV White Papers (excellent resources) NX-OS and Cisco Nexus Switching: Next-Generation Data Center Architectures (2nd Edition) by Ron Fuller, David Jansen, Matthew McPherson (chapter dedicated to OTV)
