I am trying to create an etherchannel between a Cisco 2950 and 3550 in a lab first. I want to use 2 ports on each switch as a trunk for load balance and redundancy.
If I just have one fa0/1 from each switch connected the PC's in fa 0/24 on each switch (VLAN 10) can ping each other as soon as I add the second trunk from fa0/2 on each switch the pings stop and I get the spanning tree blocking one of the ports:
01:11:14: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk FastE thernet0/3 VLAN1.
01:11:14: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking FastEthernet0/3 on VLAN0001. Inconsistent port type.
You can't bring them up one at a time . Also my self I would use " channel group X mode desirable non-silent but that is just a preference which lets the switch negotiate the etherchannel. Do a shut on the port channel itself not the interfaces . Then bring up the "port channel" (no shut) which should bring up both interfaces at the same time. Do this for both sides . When you do 1 at a time it treats it as an individual trunk link and then you have a mismatch from the far side of the link and a spanning tree loop so it shuts down 1 port , when you bring the "port channel active " it puts both ports into the port channel and should eliminate the spanning tree blocked port condition .
Shutting down the port channel and bring it back up fixed it and all is working, I can ping other the devices across the switches even when I pull out the a trunk port or shut it down, so by default is it load balancing?
Can I tell which of the trunks is getting used most?
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