Information Technology Reference
In-Depth Information
There can be complications, though, if you turn off autonegotiation on the switch but leave it active on
the workstation. Because the switch will not negotiate with the client, the client might not choose the
same duplex setting that the switch is using. See the section “Troubleshooting Ethernet 10-/100-Mb
Half-/Full-Duplex Autonegotiation,” earlier in this chapter, for additional information on the caveats of
autonegotiation.
How to Reduce Startup Delay on the Catalyst 4000/5000/6000 Switch
The following five commands show how to turn on PortFast, turn off PAgP negotiation, turn off trunking
negotiation (DISL, DTP), and turn off speed/duplex negotiation. The
set spantree portfast
command
can be done on a range of ports at once (
set spantree portfast 2/1-12 enable
). Usually
set port channel
must be turned off using a valid group of channel-capable ports. In the case that follows, module 2 has
the capability to channel with ports 2/1-2 or with ports 2/1-4, so either of these groups of ports would
have been valid to use.
Version 5.2 of Cat OS for Catalyst 4000/5000 has a new command called
set port host,
which is a macro that combines the commands
set spantree portfast, set portchannel off
,
set trunk off
into one command.
Note
Configuration
Use the following commands to reduce startup delay on the Catalyst 4000/5000/6000 switches.
Switch-A (enable)
set spantree portfast 2/1 enable
Warning: Spantree port fast start should only be enabled on ports connected
to a single host. Connecting hubs, concentrators, switches, bridges, etc. to
a fast start port can cause temporary spanning tree loops. Use with caution.
Spantree port 2/1 fast start enabled.
Switch-A (enable) set port channel 2/1-2 off
Port(s) 2/1-2 channel mode set to off.
Switch-A (enable)
set trunk 2/1 off
Port(s) 2/1 trunk mode set to off.
The changes to the configuration will be automatically saved to NVRAM.
Verification
The version of the switch software used in this document is 4.5(1). For the full output of
show version
and
show module,
refer to the section “Timing Tests with and Without DTP, PAgP, and PortFast on a
Catalyst 5000,” later in this chapter.
Switch-A (enable)
show version
WS-C5505 Software, Version McpSW: 4.5(1) NmpSW: 4.5(1)
