Information Technology Reference
In-Depth Information
To verify that PAgP is off, use the show port channel command, which follows. Be sure to specify the
module number (2, in this case) so that the command will show you the channel mode even if there is no
channel formed. If we do show port channel with no channels formed, it just says “no ports channeling.”
We want to go further and see the current channel mode.
Switch-A (enable) show port channel
No ports channeling
Switch-A (enable) show port channel 2
Port Status Channel Channel Neighbor Neighbor
mode status device port
----- ---------- --------- ----------- ------------------------- ----------
2/1 notconnect auto
not channel
2/2 notconnect auto
not channel
...
Switch-A (enable) set port channel 2/1-2 off
Port(s) 2/1-2 channel mode set to off.
Switch-A (enable) show port channel 2
Port Status Channel Channel Neighbor Neighbor
mode status device port
----- ---------- --------- ----------- ------------------------- ----------
2/1 connected off
not channel
2/2 connected off
not channel
...
To verify that trunking negotiation is off, use the set trunk off command. We show the default state here.
Then we turn trunking to off and show the resulting state. We specify module number 2 so that we can
see the current channel mode for the ports in this module.
Switch-A (enable) show trunk 2
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
2/1
auto
negotiate
not-trunking 1
2/2
auto
negotiate
not-trunking 1
...
Switch-A (enable) set trunk 2/1-2 off
Port(s) 2/1-2 trunk mode set to off.
Switch-A (enable) show trunk 2
Port Mode Encapsulation Status Native vlan
-------- ----------- ------------- ------------ -----------
2/1
off
negotiate
not-trunking 1
2/2
off
negotiate
not-trunking 1
...
We do not show an example here of turning off speed/duplex autonegotiation by manually setting the
speed and duplex on the switch; it should not be necessary except in the rarest of cases. We give an
example of how to do this in Step 10 of the next section, if you feel that it will be necessary for your
situation.
Timing Tests with and Without DTP, PAgP, and PortFast on a Catalyst 5000
The following test shows what happens with switch port initialization timing as the various commands
are applied. The default settings of the port are used first to give a benchmark. They have PortFast
disabled, PAgP (EtherChannel) mode set to auto (it will channel if asked to channel), and the trunking
mode (DTP) set to auto (it will trunk if asked to trunk). The test then proceeds to turn on PortFast and
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