[j-nsp] vpls loop avoidance

[Phil Mayers]

On 10/20/2011 08:28 PM, Sebastian Wiesinger wrote:
>
> One problem with active/standby is mac aging on the CE switch(es).
> When the primary PE goes down, the backup PE takes over and the
> CE-switches learn mac addresses on the link towards the backup PE.
> Now when the primary link comes online again, the VPLS on the primary
> PE goes active, forcing the standby PE to deactivate VPLS. The CE
> switches still have the mac addresses learned on the port to the
> standby PE so you have to wait until the mac addresses age out (or a
> packet with that source mac comes in from the primary PE).

I can think of a few ways vendors could solve this. Most simply, the 
backup PE could briefly down the link, to trigger an FDB flush. Hell, 
you could probably script this using EEM in cisco-land.