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Live VM Mobility Network Requirements

Every time someone mentions how awesome new technologies solve live VM mobility across WAN networks, I start muttering unmentionables. Live VM mobility across disjoint layer-2 subnets works great in demos, but usually fails in real life due to stale ARP caches. The only way to solve this problem for good is to implement EC2-like layer-3 forwarding in hypervisor soft switches.

Update: LISP Host Mobility seems to be a potential exception; see the comment from Nico.

For more details, watch the VM Mobility Requirements video (part of Enterasys-sponsored DCI webinar), read the Hot and Cold VM Mobility blog post or watch the recording of NFD4 session with Cisco’s Victor Moreno.

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3 comments:

  1. Hello Ivan,

    From what I've seen when playing with LISP ASM (host mobility accross subnets), the stale ARP caches resident in other VMs in the same subnet are cleared by a gratuitous ARP sent by local XTR devices so that on-subnet server to server traffic is then LISP encapsulated.

    Replies
    1. That sounds cool, but the moved VM also has an ARP cache. How is that one flushed/replaced?

    2. Use anycast gateway.

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