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| -rw-r--r-- | doc/user/vrrp.rst | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/doc/user/vrrp.rst b/doc/user/vrrp.rst index d99fc23ef5..cad850e7ac 100644 --- a/doc/user/vrrp.rst +++ b/doc/user/vrrp.rst @@ -519,6 +519,7 @@ Check: - Do you have unusual ``sysctls`` enabled that could affect the operation of multicast traffic? - Are you running in ESXi? See below. +- Are you running in a linux VM with a bridged network? See below. My master router is not forwarding traffic @@ -552,6 +553,24 @@ feature instead, explained `here Issue reference: https://github.com/FRRouting/frr/issues/5386 +My router is running in a linux VM with a bridged host network and VRRP has issues +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Issues can arise with VRRP (especially IPv6) when you have a VM running on top +of a linux host, where your physical network is in a bridge, and the VM +has an interface attached to the bridge. By default, the linux bridge will +snoop multicast traffic, and you will likely see sporadic VRRP advertisements failing +to be received. IPv6 traffic was be particularly affected. + +This was observed on a VM running on proxmox, and the solution was to disable +multicast snooping on the bridge: + +.. code-block:: console + + echo 0 > /sys/devices/virtual/net/vmbr0/bridge/multicast_snooping + +Issue reference: https://github.com/FRRouting/frr/issues/5386 + My router cannot interoperate with branded routers / L3 switches ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |