Adjusting the MaxAge Timer on a Set/Clear Command−Based IOS

To change the default MaxAge timer for a particular VLAN, use this Privileged mode command :

spantree maxage <time value> <VLAN>

In the following example, 5 refers to the MaxAge time and 1 refers to the VLAN:

spantree maxage 5 1

Preparing to Enable EtherChannel

When preparing to enable EtherChannel, you should check four items before configuring an EtherChannel bundle. They are as follows:

∙If a bundle uses trunked ports, each port must be configured with the same allowed VLAN range. If the VLAN ranges are not configured identically for both ends of all the trunked links in the bundle, the data traffic for the particular missing VLAN traffic is not allowed and the frames for that VLAN are dropped.

∙Trunked ports will not form a channel when set to the auto or desirable mode using the set port channel command. However, trunked ports on which VLANs are allowed will continue to transmit data traffic across their trunk links.

∙You must verify that port security is disabled on all channeled ports. By enabling port security, the port shuts down when it receives packets containing a source address that doesn’t match the secure address of the port.

∙All ports in a channel must be enabled. Any disabled ports are considered link failures by the switch, and traffic for those ports is automatically transferred to any remaining ports in the bundle.

If these criteria are not met, then you will receive an error for each item that is not configured correctly when you try to configure EtherChannel.

Viewing the Port Setting for EtherChannel on a Set/Clear Command−Based Switch

To view the port settings on ports you are configuring for EtherChannel on a Set/Clear command−based switch, use the following command in Privileged mode. Use this command to compare the settings to make sure they match the other ports waiting to be configured as a bundle:

show port capabilities <module number/port number>

For this example, 2 is the module number and 1 is the port number. The output shows that the port is already configured to participate in a bundle:

catalyst5000> (enable) show port capabilities 2/1

219

Creating an EtherChannel on a Set/Clear Command−Based Switch

To create an EtherChannel bundle, you must enable EtherChannel on two or more ports. On a Set/Clear command−based switch, use the following Privileged mode command to enable EtherChannel:

set port channel <port list> mode <on|off|desirable|auto>

The following output shows 2 as the module number and 1 through 4 as the port numbers:

catalyst5000> (enable) set port channel 2/1−4 ?

catalyst5000> (enable) set port channel 2/1−4 mode ?

catalyst5000> (enable) set port channel 2/1−4 mode auto Port(s) 2/1−4 channel mode set to auto.

catalyst5000> (enable)

Table 10.8 explains the syntaxes available for the mode option. The mode on each port can be set to on, off, auto, or desirable.

Table 10.8: The four mode options for configuring an EtherChannel bundle on a switch.

220

another port that is in the desirable or auto mode.

Verifying the EtherChannel Configuration

To verify the EtherChannel configuration on a Set/Clear command−based switch, use this command:

catalyst5000> (enable) show port channel ?

catalyst5000> (enable) show port channel 2/1 ? Usage: show port channel [mod[/port]] [statistics]

show port channel [mod[/port]] info [type] (type = spantree|trunk|protocol|gmrp|gvrp|qos)

catalyst5000> (enable)

———— ————————————————— ————————————— ——————————————

2/1

Defining an EtherChannel Administrative Group

To define the administrative group, use the following Privileged mode command:

set port channel <module/port list> <administrative group number>

For example:

Catalyst5002> (enable) set port channel 2/1−4 10

Port(s) 2/1−4 are assigned to admin group 10.

Viewing an EtherChannel Administrative Group

To view an administrative group configuration, use the following command:

show channel group [administrative group number]

For example, to view group 10, use the following command:

221

group

———— ———— —————————————————————————————— ————————————— ————————

10 2/1

10 2/2

10 2/3

10 2/4

Configuring EtherChannel on an IOS−Based Switch

To configure EtherChannel on an IOS command−based switch such as the 1900EN series and 2800 series switches, use the Global Configuration port−channel command followed by the mode (on, desirable, or auto):

port−channel mode <on|desirable|auto>

Here, the mode is auto:

port−channel auto

Identifying the Template Port

With the IOS−based switches, you must identify a template port for the port−channel parameters. To do so, use the following command in Global Configuration mode:

port−channel template−port <template port>

In this case, the FastEthernet 0/26 is port A on the 1900 series switch:

Catalyst1900(config)# port−channel template−port fastethernet 0/26

Verifying the EtherChannel Configuration on a Command Line Interface IOS

To verify the configuration on an IOS−based switch, use this Privileged mode command:

show interface

The output should look similar to the following on a CLI−based command switch:

PortChannel is Enabled

802.1d STP State: ForwardingForward Transitions: 1 Port−channel mode: auto, preserve−order: Disabled Port parameters template port: A

Active port: A PortMemberPriorityCap.PartnerPartnerPartnerPartner Device−idPort−idPriorityCap.

——————————————————————————————

AYes128100−00−00−00−00−0000

BYes128100−00−00−00−00−0000

The output should look similar to the following on a Set/Clear command−based IOS:

222

catalyst5000> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING>

slip 0.0.0.0 dest 0.0.0.0

sc0: flags=63<UP,BROADCAST,RUNNING>

vlan 1 inet 208.44.88.4 netmask 255.255.255.192 broadcast 208.44.88.63 catalyst5000> (enable)

Enabling PortFast on a Set/Clear Command−Based Switch

To enable PortFast on a Set/Clear command−based switch port, use the following Privileged mode command:

set spantree portfast <module/port> enable

In this example, 2 is the module number and 1 is the port number:

catalyst5000> (enable) set spantree portfast ?

catalyst5000> (enable) set spantree portfast 2/1 ?

catalyst5000> (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.

Disabling PortFast on a Set/Clear Command−Based Switch

To disable PortFast on a Set/Clear command−based switch port, use the following Privileged mode command:

set spantree portfast <module/port> disable

In this example, 3 is the module number and 8 is the port number:

set spantree portfast 3/8 disable

Enabling PortFast on a CLI−Based IOS Switch

To enable PortFast on a Cisco IOS command−based switch, use this Interface Configuration mode command:

spantree start−forwarding

223