[AusNOG] VPLS OSPF question

[John Edwards]

Hi Brad,

One caveat that I would add here is that not all VPLS' are created equal, and that there are non-unique cases where they don't support multicast. All VPLS will have some kind of multicast limitation, but not usually one that you'll notice.

This is important to your question, because OSPF requires multicast to function out of the box on a LAN, even a virtual private one. Not many applications rely on multicast, so it's easily overlooked by purveyors of VPLS.

It is possible to work around this, but in doing so you might be overlooking better solutions. If none of your 200 sites have redundant connectivity and your VPLS cannot logically split, then you may even find that static routes help you to get more sleep.

John


On 16/04/2013, at 4:44 PM, Brad McGinn wrote:

> My fairly basic understanding of VPLS is kind of like EoMPLS or even one big broadcast domain.  I assume any IGP could potentially work across it but some factors must be taken into consideration:  eg flapping sites, latency, reference bandwidth, DR/BDR placement, multicast transmission and so on.
>  
> So, with that in mind, I'm wondering the following:
> -    would it be wise to run an IGP across a VPLS backbone with over 200 sites? or would BGP be better? or even something else?
> -    if an IGP is the go, would one use OSPF?

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