Transparent mode & L2TPv3 not working on HA clusters

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Peter
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Joined: 10 Apr 2008, 14:14
Location: Clavister HQ - Örnsköldsvik

Transparent mode & L2TPv3 not working on HA clusters

Post by Peter » 23 Apr 2015, 14:35

This FAQ applies to:
  • Clavister cOS Core, version 10 and up.
Question:
  • Why is it not possible to configure L2TPv3 or Transparent mode on a high availability cluster?
Answer:

There is no state synchronization for Transparent Mode and no loop avoidance.

Basically, running transparent mode on a HA cluster would result in the same situation as when two switches are connected to each other over multiple links. One single packet entering the system could in the worst case cause a never-ending packet loop between the two nodes. Besides keeping the HA cluster fully busy, this will also mean that multiple copies of the packet will be generated on all involved interfaces, meaning that the HA cluster would more or less become a packet generator (if it was allowed)

And since L2TPv3 relies on transparent routing to bridge the networks using layer 2, it will not work on high availability clusters as well.

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