L3 Port channel point to mutipoint

[collinsjl]

Currently we have 4 remote sites and one main site

The main site has 2 redundant 250M connections to the ISP VPLS circuit

All remote sites have 2 redundant 50M connections to the same ISP VPLS

I have assigned routed ports on all connections and basically have split off the two links in to separate broadcast domains ie:

172.16.200.0/24

172.16.201.0/24

We are running EIGRP so we have ECMP running to all locations.

The VPLS is configured basically as on big mesh so really its like one VLAN - I am segmenting traffic at L3 but at L2 really its not.

I am wondering if I can run L3 portchannels on the links instead and run one ip at each location and get the same result?

So in a 2960XR at remote location 1 I would have

Int range g 1/0/1-2

No switchport

channel-group 10 mode on  (I dont think LACP will work multipoint)

int po 10

IP address 172.16.200.X 255.255.255.0

Still run EIGRP for dynamic routing

And do this at all the remote locations

At the main site 3850

just do the same for the two interfaces that are going into the VPLS.

Will this work if the port channels are not point to point?  Kind of hard to lab this up without a hub and who has those nowadays.

[Reza Sharifi]

Point to multi-point Portchannel will not work.  You can do the same using point to point Portchannels with /30s. So, instead of putting everything in one subnet, you put them in multiple /30s.

HTH 

[collinsjl]

Unless you can have subinterfaces in a L3 port channel that wont work for the design.  All remote sites need to be connected to the main site and each other.  Thanks for the reply.  I think that because the ISP is basically a huge wire nut with all the cables bundled together (they do not run spanning tree) that this might be possible if the mode was on but I guess not. 

I was thinking this could be a good use case for L3 port channels.  I will stick with EIGRP and ECMP. 

CDP is all jacked up between the switches and shows all ports connected even though they are segmented L3 because of the way the VPLS is meshed together.

Thanks again.

[Reza Sharifi]

I agree with you for keeping the design you have. I don't think it is worth going through all the trouble to eliminate a few subnets.

Good Luck!

[Joseph W. Doherty]

I have assigned routed ports on all connections and basically have split off the two links in to separate broadcast domains ie:

BTW, regarding separate broadcast domains, no, I don't believe you have.  Basically, you have two networks within the same broadcast domain (assuming broadcasts are replicated to all connections).

I am wondering if I can run L3 portchannels on the links instead and run one ip at each location and get the same result?

Yea, you should, if you could get port-channel to work, but both (physical) sides (of link) need to agree on it, and as far as I know it requires same physical device on both ends.  That's something you would need to discuss with your VPLS provider, but my guess, they wouldn't support it.  Even if they did, and you did, you would need to consider port-channel load-balancing being used.  With router ECMP, you usually already have L3 load balancing.

Will this work if the port channels are not point to point?  Kind of hard to lab this up without a hub and who has those nowadays.

It should, again if you could get your provider to support it.  Remember port-channel is a binding of L2 links.  No requirement for a L3 p2p on top of it.

As to using a hub, port-channel won't work with a hub, it requires another switch that supports it.  With a hub and a router, the router would need to bridge between its ports, then you have a L2 loop which you needs to deal with.  You would end of, somehow, blocking one link, i.e. you would only be actively using one while the other was a warm standby.

There are other link binding technologies, but again, those require both (physical) sides to support them.

What you doing now is probably "good enough".  However, if you wanted to get the most out of your current setup, something like PfR's PIRO could dynamically load balance using both links.  PfR can adjust its outbound, not only to load balance on its immediate egress ports, but also based on the destination sites ingress.  Unfortunately, I don't think it's supported on low end switches.