Information Technology Reference
In-Depth Information
Configuration
Here is an example of setting PortFast on a Fast Ethernet port. These examples use Enterprise edition
software, version 8. The 1900 automatically saves the configuration after changes have been made.
Remember, you would not want PortFast enabled on any port that connects to another switch or
hub—only if the port attaches to an end station. The configuration is saved automatically to NVRAM.
1900#
show version
Cisco Catalyst 1900/2820 Enterprise Edition Software
Version V8.01.05
Copyright (c) Cisco Systems, Inc. 1993-1998
1900 uptime is 0day(s) 01hour(s) 10minute(s) 42second(s)
cisco Catalyst 1900 (486sxl) processor with 2048K/1024K bytes of memory
Hardware board revision is 5
Upgrade Status: No upgrade currently in progress.
Config File Status: No configuration upload/download is in progress
27 Fixed Ethernet/IEEE 802.3 interface(s)
Base Ethernet Address: 00-50-50-E1-A4-80
1900#
conf t
Enter configuration commands, one per line. End with CNTL/Z
1900(config)#
interface FastEthernet 0/26
1900(config-if)#
spantree start-forwarding
1900(config-if)#
exit
1900(config)#
exit
1900#
Verification
One way to verify that PortFast is on is to look at the configuration. Remember, a Fast Ethernet port must
say that it is on. An Ethernet port has PortFast enabled unless the configuration shows that it is off. In
the configuration that follows, interface Ethernet 0/1 has PortFast turned off (you can see the command
to turn it off), interface Ethernet 0/2 has PortFast on (you see nothing, which means that it is on), and
interface Fast Ethernet 0/26 (port A in the menu system) has PortFast on (you can see the command to
turn it on).
1900#
show running-config
Building configuration...
...
!
interface Ethernet 0/1
no spantree start-forwarding
!
interface Ethernet 0/2
!
...
!
interface FastEthernet 0/26
spantree start-forwarding
!
