[j-nsp] vpls loop avoidance

[Phil Bedard]

Standards-based STP BPDUs are sent untagged, which might be an issue if
the links to your CE switches are tagged only.  Cisco PVST+ sends the
BPDUs with a VLAN tag.


I remember seeing some blurb about not connecting two CE devices to each
other if they are connected to two different PEs with the same site-id.
Is this one switch or two?


Phil 

On 10/11/11 4:14 PM, "Keegan Holley" <keegan.holley at sungard.com> wrote:

>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-confi
>>>guring-ethernet-switch-as-the-ce-device.html
>>>  _______________________________________________
>>> juniper-nsp mailing list juniper-nsp at puck.nether.net
>>> https://puck.nether.net/mailman/listinfo/juniper-nsp
>>>
>>
>>
>>
>> --
>> Humair
>>
>>
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