Switching - EtherChannels
We have covered that I would
consider the basics of switching. We've seen how to make a switchport an access
port that an end user would connect to. We've setup trunks between switches
utilizing DTP and with static configurations. We've taken a basic look at
802.1q, we've created a router-on-a-stick so we could route traffic between
vlans, and we've setup VTP so we could tell all out network switches about
vlans. Now let's get into some of the advanced topics. I'll start with
EtherChanneling and go from there.
EtherChanneling, also know as
PortChanneling, is taking multiple links and creating a single logical link.
This is mostly for spanning-tree benefit. I won't go over STP as this blog is
about etherchannels and not STP. If you have questions on STP feel free to
shoot me a message.
There are 3 types of EtherChannels,
1)static 2)PAgP 3)LACP. Static is just creating an etherchannel and putting it
in the on mode. PAgP is the Cisco proprietary negotiation method of creating an
etherchanel and LACP is the IEEE standard method of etherchannel negotiation.
When using one of the etherchannel negotiation methods PAgP and LACP these act
similar to DTP in that at least one end needs to be desireable or active. The
other end can be in auto or passive, but if both ends are auto or passive then
neither side will start the etherchannel negotiation.
