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Show 27 — Layer 2 Data Centre Interconnection

Scott Lowe and I planned to have a discussion around L2 Data Centre connection the VMworld 2010 in Copenhagen but Scott and I could not meetup. So we recorded this podcast to start talking about some of the issues, technology and solutions on L2 DCI. I’m not sure that we have all the technology or knowledge in place, so keep watching for more discussions in the future. We have only scratched the surface. If anyone else wants to discuss the topic, please get int contact as more would be better.

Because the recording lasted for a hour and a half, we split the show into two parts. This is Part 1 — Layer 2 Data Centre Interconnection where we talk about the problems, challenges. Next week we go into more esoteric topics on vCloud networking, OTV, VEPA and network appliances as virtual machines.


Scott Lowe Ivan Pepelnjak @ioshints

Layer 2 Data Centre Interconnect — open discussion

  • The challenges of extending L2 DCI network betweens sites.
  • Outlining the threats of large Layer 2 spaces in terms of network vulnerability.
  • quick review of vMotion traffic and its requirements.
  • Reviewing the impact of fault domains and L2 VLAN space as uncontrollabl
  • It’s all about the application.
  • Latency, latency and the impact on vMotion switchover.
  • Greg’s ariticle on the Traffic Trombone and Ivan’s extensions to it.
  • It’s worth remembering that Network Load Balancers can be more effective than using vMotion is certain use cases.
  • vMotion is not for unplanned outages or DR. More for planned outages or possibly workload balancing.
  • Debating whether we are able to QoS L2 traffic when flowing between data centers thus answering the question about guaranteeing levels of service for multiple hosts in a VLAN.
  • Some humour on Pseudowire over MPLS over GRE over IP. But’s its actually real.
  • Some review on the F5 EtherIP technology and whether it’s relevant to the solution.


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About the author

Greg Ferro

Greg Ferro is the co-host of Packet Pushers. After surviving 25 years in Enterprise IT with only minor damage, he uses his networking expertise for good in the service of others by deep diving on technology and industry. His unique role as an inspirational cynicist brings a sense of fun, practicality and sheer talent to world of data networking and its place in a world of clouds.

He blogs regularly at and the podcasts are at

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