Multiple lan connection - trunking - STP

[yuhefm]

Hi,

We have 2 main site connected with a 1 GB FO link, with 2 minor site on the way (no user there). I'm looking to get a new point to point link (layer 2) for redundancy between the 2 main site only . We have the same network on both side plus some vlan.  (see attachment)

As I understand, there is no way to trunk (link aggregation) when there is other device between the two trunking switch, is that right ?

So the only solution here would be to connect both link and to turn STP on ? In this case it will always use the link with the highest priority ?

Is there any device I could plug on both side to manage the load balancing and failover ?

Thank you

[Vince_Whirlwind]

I've never used 4200s (I remember 4100s) but if they support tunnel interfaces, perhaps you could setup a tunnel via both routes then link aggregate the two tunnel interfaces on eache end. Just a wild idea - I have never tried link aggregating tunnel interfaces before.

Alternatively, you could put a pair of circulators on each end of the 5km & 2km links, then patch through one link so it goes directly 4200-4200 so you can then link aggregate that link with the new ISP link. You still need spanning tree, and the two branch offices will only communicate with each other via the two main offices as a result.

[yuhefm]

I had a look but I can't setup tunnel.. as the 4202 are only switch and have no router module in them. I've got no room to add one. I may contact my hp reseller to see if a tunnel solution could work, and then maybe add new routers.

About the circulator it's a good idea but I don't have my hand on every part of the line.

Thank you !