[j-nsp] About RD in vpls multi-homing environment.

Pyxis LX pyxislx at gmail.com
Wed Apr 15 11:32:36 EDT 2015

Hi, Adam & Sebastian.

Thank you for the reply.
Unique RDs in VPLS indeed reduce the downtime which should be regarded
as the best practice.
I also forgot to consider the RR case.


On 4/14/15, Adam Vitkovsky <Adam.Vitkovsky at gamma.co.uk> wrote:
> Hi Nat,
> You should always want to use unique RDs (possibly type-2 RD using router-id
> IP address) in any MPLS services when RRs are involved.
> RD as the name suggests makes the route (or any information carried)
> distinguishable/unique thus not subject for BGP best path selection.
> As you know BGP only advertises best-paths to its neighbours so if two sites
> advertise the same information to the RR -RR will select only one and
> advertise it to the rest of the AS -unless you make the otherwise same
> information unique by prepending it with a unique RD.
> AS you might rightly infer using unique RDs will increase the amount of
> information flooded to the PEs but the advantage, as Sebastian pointed out,
> is that PEs will have a backup route at hand and thus can use techniques to
> fast failover to the backup path if the primary path is down.
> adam
>> -----Original Message-----
>> From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
>> Of Pyxis LX
>> Sent: 11 April 2015 19:18
>> To: juniper-nsp at puck.nether.net
>> Subject: [j-nsp] About RD in vpls multi-homing environment.
>> Hi, All.
>> I am not sure whether PEs connected to the same vpls site should be
>> configured with the same RD or not.
>> "JNCIS-SP Study Guide Part 3" P.415 states that both PE connected to
>> the same site should be configured with the same RD.
>> (The topology chart is available at P.409, PE2 & PE3 connect to the same
>> site)
>> However, when I configure them with the same RD, PE3 will not announce
>> any l2vpn routes to other PEs, is that normal?
>> And I found another configuration example on Juniper website:
>> http://www.juniper.net/documentation/en_US/junos14.2/topics/topic-
>> map/vpls-bgp-multihoming.html
>> This example suggests that PE1 and PE2 should use different RDs.
>>  Which one is correct, or I take the wrong example?
>>  Thank You.
>> -Nat
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