[j-nsp] Application of L2 VPN in Real World Scenario

[Ian MacKinnon]

Steinar,
Do you have any decent refs or axamples for getting started with L2circuit?

ie we have an existing pure L3 set up, what do we need to do to add L2 
fuctionality across multiple sites?

Thanks

sthaug at nethelp.no wrote:
>> I have to jump in, since I am also interested :-)
>>
>> My question is, what do you think the cost/benefit of L2VPN over VPLS?
>> It seems that L2VPN is restricted to point-to-point and there is a
>> separate vrf (and a routing table) for each link, while VPLS maintains
>> a single vrf and routing table. Have you guys thought about using
>> VPLS? Or is there any problems with it? Maybe scalability?
>
> Can't really comment the (Juniper proprietary) L2VPN. However, we use
> both Martini tunnels (L2circuit in Juniper terminology) and VPLS. The
> two technologies are quite different:
>
> - L2circuit (and L2VPN) give you a point-to-point link. You can think
> about the technology as a pipe where packets are inserted at one end
> and come out at the other end. No MAC address learning is necessary.
> Troubleshooting is fairly simple (no need to go looking for specific MAC
> addresses and where they originate). Scaling is fairly good - we have
> M7i routers with more than 2000 L2circuits.  You need to watch your FEB
> memory utilization, though.
>
> - VPLS give you a layer 2 multipoint network - in effect you are making
> your network look like a large LAN. MAC address learning is necessary,
> and only the MX boxes are able to do this in hardware. Replication of
> broadcast/multicast/unknown unicast traffic is at the *source*, which
> has the potential to melt down your network (e.g. one 100 Mbps stream
> replicated to 20 different PE routers gives you 2 Gbps of traffic from
> your ingress router towards your network core). Both the technology
> and the troubleshooting is significantly more complex than L2circuit/
> L2VPN.
>
> I don't want to give the impression that VPLS is all gloom and doom.
> Juniper has done a reasonable job of making the technology stable,
> especially in later JunOS versions, and P2MP LSPs help significantly
> with the ingress replication problem. However, L2 point-to-point is
> still a significantly simpler technology no matter how you look at it.
>
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
> _______________________________________________
> juniper-nsp mailing list juniper-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/juniper-nsp


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