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[Xav Paice <xav.paice@xxxxxxxxxxxxx>]

Public bug reported:

OS: Xenial, Ocata from Ubuntu Cloud Archive
We have three neutron-gateway hosts, with L3 HA enabled and a min of 2, max of 3.  There are approx. 400 routers defined.

At some point (we weren't monitoring exactly) a number of the routers
changed from being one active, and 1+ others standby, to >1 active.
This included each of the 'active' namespaces having the same IP
addresses allocated, and therefore traffic problems reaching instances.

Removing the routers from all but one agent, and re-adding, resolved the
issue.  Restarting one l3 agent also appeared to resolve the issue, but
very slowly, to the point where we needed the system alive again faster
and reverted to removing/re-adding.

At the same time, a number of routers were listed without any agents
active at all.  This situation appears to have been resolved by adding
routers to agents, after several minutes downtime.

I'm finding it very difficult to find relevant keepalived messages to
indicate what's going on, but what I do notice is that all the agents
have equal priority and are configured as 'backup'.

I am trying to figure out a way to get a reproducer of this, it might be
that we need to have a large number of routers configured on a small
number of gateways.

** Affects: neutron
     Importance: Undecided
         Status: New


** Tags: canonical-bootstack

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https://bugs.launchpad.net/bugs/1731595

Title:
  L3 HA: multiple agents are active at the same time

Status in neutron:
  New

Bug description:
  OS: Xenial, Ocata from Ubuntu Cloud Archive
  We have three neutron-gateway hosts, with L3 HA enabled and a min of 2, max of 3.  There are approx. 400 routers defined.

  At some point (we weren't monitoring exactly) a number of the routers
  changed from being one active, and 1+ others standby, to >1 active.
  This included each of the 'active' namespaces having the same IP
  addresses allocated, and therefore traffic problems reaching
  instances.

  Removing the routers from all but one agent, and re-adding, resolved
  the issue.  Restarting one l3 agent also appeared to resolve the
  issue, but very slowly, to the point where we needed the system alive
  again faster and reverted to removing/re-adding.

  At the same time, a number of routers were listed without any agents
  active at all.  This situation appears to have been resolved by adding
  routers to agents, after several minutes downtime.

  I'm finding it very difficult to find relevant keepalived messages to
  indicate what's going on, but what I do notice is that all the agents
  have equal priority and are configured as 'backup'.

  I am trying to figure out a way to get a reproducer of this, it might
  be that we need to have a large number of routers configured on a
  small number of gateways.

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