[AusNOG] MPLS/VPLS solution

[Lincoln Dale]

On 10/09/2010, at 11:48 AM, Ben Dale wrote:
> I think the article misses the key selling point of VPLS which is separation of routing from customer and provider, in which case there should never be any reason to see broadcast storms inside a VPLS when all CE devices are L3.  

actually, i see it differently.  VPLS is often used to transport L2 between datacenters, i.e. common L2 domain, a shared ethernet segment if you will.  that is what the article is mostly referring to.

the challenges outlined in the article are valid and real.
i've seen outages which have taken out both primary and DR facilities as a result of some of the challenges highlighted.

reality is that that the OP didn't say what they wanted a VPLS network for and what the characteristics they are looking for with it.
but if the requirement is L2 (e.g. for server virtualization and moving VMs across physical locations, or geographically-diverse clustering where the cluster software requires L2), then VPLS is one way that requirement can be met.
is it the only way?  no.  you could use any of: L2 ethernet trunks,  EoMPLS (point to point), L2TPv3 (pseudowires) over IP, PLSB -- or -- my favourite, if this is the application -- OTV.

each has their strengths and weaknesses., as always use the right tool for the right job.
while one can often shoehorn a technology to meet a solution, often the result is a technology or solution that is twisted and broken as a result of using the right (or wrong) tool .


cheers,

lincoln.