LACP Prob

[is84]

i'm using 3com switches.

Actually I have a prob in configuring LACP. I try to connect 3 switches together, each switches at different building.

When I try to connect switch A to switch B with link aggregation group 1, the port is UP,

then connect switch B to switch C with link aggregation group 2, the port is also Up

But the problem appear when I try to connect switch A to switch C with link aggregation group 3. but if I connected switch A to switch C without Link aggregation the connection is Fine.

All the port are configured with same priority.

At first I thought the prob is because of Spanning tree, but when I enable the STP the prob is still the same.

P.S. This thread has been moved from Switches, Hubs, Modems (Legacy ITRC forum) to Comware-Based. - Hp Forum Moderator

[Vince-Whirlwind]

You definitely need STP enabled on all 3 switches before you create a link from A to C.

[sdide]

Hi,

The following sentence, makes me a bit cautios

"At first I thought the prob is because of Spanning tree, but when I enable the STP the prob is still the same."

I strongly advise you enable STP in a topolygy with physical loops - unless you use some other loop-prevention technology you are confident with. Loops are a bad thing.

If you didn't have STP enabled at first in a triangle topology, you would probably have a loop. If you had STP enabled, a link would be blocked (depending on the root-bridge)

Regards