Information Technology Reference
In-Depth Information
Showing What Happens When a Link Breaks and Is Restored
When a port in the channel goes down, then any packets that would normally be sent on that port are
shifted over to the next port in the channel. You can verify that this is happening by using the
show mac
command. In our test bed, we will have Switch A send
ping
packets to Switch B to see which link the
traffic is using. First we will clear the counters and then use
show mac
, send three
ping
s, and use
show
mac
again to look at which channel the
ping
responses were received on.
Switch-A (enable)
clear counters
This command will reset all MAC and port counters reported in CLI and SNMP.
Do you want to continue (y/n) [n]? y
MAC and Port counters cleared.
Switch-A (enable)
show port channel
Port Status Channel Channel Neighbor Neighbor
mode status device port
----- ---------- --------- ----------- ------------------------- ----------
2/1 connected on channel WS-C5505 066509957(Sw 2/1
2/2 connected on channel WS-C5505 066509957(Sw 2/2
2/3 connected on channel WS-C5505 066509957(Sw 2/3
2/4 connected on channel WS-C5505 066509957(Sw 2/4
----- ---------- --------- ----------- ------------------------- ----------
Switch-A (enable)
show mac
Port Rcv-Unicast Rcv-Multicast Rcv-Broadcast
-------- -------------------- -------------------- --------------------
2/1
0
18
0
2/2
0
2
0
2/3
0
2
0
2/4
0
2
0
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)
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
24
0
2/2
0
2
0
2/3
0
2
0
2/4
0
2
0
