Can combine from two to eight parallel Ethernet links
1900 Switches need 8.00.03 or later Enterprise Edition software
2900 Switches need IOS 11.2(8)SA or later
2950 Switches need IOS 12.0(5.2)WC(1) or later
There are three different modes for EtherChannelauto, desirable, and on:
- auto tells switch to wait for other switch to start EtherChannel negotiations. If auto is set on both sides, EtherChannel will never formboth sides are waiting for the other side to start negotiating!
- desirable tells switch it is willing to turn EtherChannel on.
- on tells switch it wants to form an EtherChannel.
Only the combinations of auto-desirable, desirable-desirable, and on-on will allow a channel to be formed.
If a device on one side of the channel does not support PAgP, such as a router, the device on the other side must have PAgP set to on.
All ports must be identical
- Same Speed and Duplex
Cannot mix Fast Ethernet and Gigabit Ethernet
Must all be VLAN trunk or non-trunk operational status