Information Technology Reference
In-Depth Information
Now at this point, we have received the
ping
responses on port 3/1, so when Switch B console sends a
response to Switch A, the EtherChannel uses port 2/1. Now we will shut down port 2/1 on Switch B.
From Switch A, we will issue another
ping
and see what channel the response comes back on. (Switch
A is sending on the same port to which Switch B is connected. We just show the received packets from
Switch B because the transmit packets are farther down in the
show mac
display.)
1999 Dec 19 01:30:23 %PAGP-5-PORTFROMSTP:Port 2/1 left bridge port 2/1-4
Switch-A (enable)
ping 172.16.84.17
172.16.84.17 is alive
Switch-A (enable)
show mac
Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast
-------- -------------------- -------------------- --------------------
2/1
3
37
0
2/2
1
27
0
2/3
0
7
0
2/4
0
7
0
Notice that now that port 2/1 is disabled, EtherChannel automatically uses the next port in the channel,
2/2. Now we re-enable port 2/1 and wait for it to join the bridge group; then we issue two more
ping
s.
1999 Dec 19 01:31:33 %PAGP-5-PORTTOSTP:Port 2/1 joined bridge port 2/1-4
Switch-A (enable)
ping 172.16.84.17
172.16.84.17 is alive
Switch-A (enable)
ping 172.16.84.17
172.16.84.17 is alive
Switch-A (enable)
show mac
Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast
-------- -------------------- -------------------- --------------------
2/1
5
50
0
2/2
1
49
0
2/3
0
12
0
2/4
0
12
0
Note that these
ping
s are sent from port 2/1, so when the link comes back up, EtherChannel will again
add it to the bundle and use it. All this is done transparently to the user.
Commands Used in This Section
Commands to use for setting the configuration include these:
•
set port channel on
—To turn on the EtherChannel feature
•
set port channel auto
—To reset the ports to their default mode of auto
•
set port channel desirable
—To send PAgP packets to the other side requesting that a channel be
created
•
set port enable
—To enable the ports after
set port disable
or after an errdisable state
•
set port disable
—To disable a port while other configuration settings are being made
•
set trunk desirable
—To turn on trunking by causing this port to send a request to the other switch
that this be a trunk link and, if the port is set to negotiate (the default setting), to negotiate the type
of trunking to use on the link (ISL or 802.1q)
Commands to use for verifying the configuration include these:
•
show version
—To display what version of software the switch is running
