[j-nsp] vpls loop avoidance

[Keegan Holley]

2011/10/11 Humair Ali <humair.s.ali at gmail.com>

> Hi Keegan
>
> As far as I know , in VPLS, it uses split horizon as loop avoidance
> mechanism , and  you should not see any loop occurring in a VPLS
> setup,(pending the rest of config is correct)
>

Yes it is BGP signaled so that will solve the loops on the core facing
interfaces.


>
> The only way you could have a loop in VPLS is when you start having your CE
> dual homed , where in that case you need to either configure STP , or you
> could use the primary/backup knob to define which PE is the primary and
> which is the back up.
>

STP doesn't seem to work here.  Only cisco PVST which doesn't help me on an
EX4200.  Primary/backup has to do with multihoming which works as well.  I'd
like to know why this works when the site-id's are the same and why the
l2forwarding instance doesn't work.  I'm also curious why cisco pvst works
and none of the standards based protocols.



>
> On 11 October 2011 20:19, Keegan Holley <keegan.holley at sungard.com> wrote:
>
>> I'm trying to get my handle on vpls loop avoidance and I can't remember
>> the
>> default behavior regarding site-id's and node-id's.  I remember reading
>> about it in one config guide or another but I can't seem to find it now.
>> I'm trying to remember if broadcast, multicast and unknown unicast is
>> flooded between PE router interfaces with the same site id's and maybe
>> just
>> some general guidelines on their behavior.  I'm trying to understand best
>> practices for loop avoidance.  It seems to loop with any standards based
>> STP
>> protocol if two or more interfaces are connected to routers configured
>> with
>> the same site-id.  The behavior I see seems to be the opposite of what the
>> website says.
>>
>>
>> http://www.juniper.net/techpubs/en_US/junos10.4/topics/concept/vpn-configuring-ethernet-switch-as-the-ce-device.html
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>
>
>
> --
> Humair
>
>