Mapping VLANs to a Trunk Port

In the last example, we assigned port 2/1 as a trunk port using ISL encapsulation. Notice that we did not specify the VLANs to trunk. By default, all VLANs would be trunked. You can assign only VLANs 1 through 200 to be trunked across this configured trunk link, as shown here:

Console> (enable) set trunk 2/1 on 1−200 isl Adding vlans 1−1005 to allowed list.

Please use the Ôclear trunk’ command to remove vlans from allowed list. Port(s) 2/1 allowed vlans modified to 1−1005.

Port(s) 2/1 trunk mode set to on. Port(s) 2/1 trunk type set to isl.

Configuring a Trunk Port on a Cisco 1900EN Series

To configure a trunk on a 1900EN series switch, you use the trunk command. The 1900 switch has the same port negotiation options as the 5000 series, but only runs the DISL encapsulation method. You can see the syntaxes available for configuring a 1900EN series switch by using the trunk option from Interface Configuration mode:

trunk is the only command needed to trunk a port once you are in Interface Configuration mode for the port that needs to be trunked. You can set the trunked port to always be a trunk link, using the following command:

1900EN(config−if)#trunk on

Clearing VLANs from Trunk Links on a Cisco 5000 Series

All VLANs are configured on a trunk by default. They remain configured unless cleared by an administrator. If you want a trunk link not to carry certain VLAN information—perhaps because you want to stop broadcasts on a certain VLAN from traversing the trunk link, or you want to stop topology change information from being sent across a link where a VLAN is not supported—use the clear trunk command:

5000> (enable) clear trunk 2/1 4−1005 Removing Vlan(s) 4−1005 from allowed list.

Clearing VLANs from Trunk Links on a Cisco 1900EN Series

To remove VLANs from a trunk port on a 1900, use the no trunk−vlan command in Interface Configuration mode. First, to view the possible options for the command, use the following:

1912(config−if)#no trunk−vlan ? <1−1005> ISL VLAN index

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To remove VLAN 2 from a trunked port use the following command:

1912(config−if)#no trunk−vlan 2 1912(config−if)#

Note No command is available to clear more then one VLAN at a time on the 1900.

Verifying a Trunk Link Configuration on a 5000 Series

To verify your trunk ports on a Catalyst 5000 series, use the show trunk command as follows:

Console> (enable) show trunk 2/1

The following shows the results:

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

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

2/1 1−3

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

Console> (enable)

Verifying a Trunk Link Configuration on a 1900EN Series

The 1900EN series uses the show trunk command just as the 5000 series does, but can view only the two Fast Ethernet ports 26 and 27. The IOS on the 1900EN identifies these ports as Port A and Port B. To verify the trunk link configuration, do the following:

1. First, look at the syntaxes available for the show trunk command:

1912#show trunk ?

A Trunk A

B Trunk B

2. Now, look at the syntaxes available for the Fast Ethernet port 26, which is identified by an “a”:

Configuring the VTP Version on a Catalyst 5000 Switch

To configure VTP version 2, use the set vtp v2 enable command. Let’s look at an example:

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5000> (enable) set vtp v2 enable

This command will enable the version 2 function in the entire management domain.

All devices in the management domain should be version2−capable before enabling.

Do you want to continue (y/n) [n]? y VTP domain modified

5000> (enable)

Configuring a VTP Domain on a Catalyst 1900 Switch

The 1900EN series switches only use VTP version 1. The switch can be a member of only one VTP domain. To set the switch to the Coriolis domain, use the following command:

1912(config)# vtp domain coriolis

Setting a VTP Domain Password on a Catalyst Switch

To set the VTP domain password to 1234 on a Catalyst 1900, use the following command:

1912(config)# vtp password 1234

Configuring a Catalyst 1900 Switch as a VTP Server

The 1900EN series switches only use VTP version 1. No configuration options exist for VTP versions. To set the switch as a VTP server for the domain use the following command:

1912(config)# vtp server

Configuring a Catalyst 1900 Switch as a VTP Client

To configure the switch as a VTP client use the following command:

1912(config)# vtp client

Configuring a Catalyst 1900 Switch for Transparent Mode

To configure the switch to operate in transparent mode, use the following command:

1912(config)# vtp transparent

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Configuring VTP Pruning on a Catalyst 1900 Switch

To configure the switch for VTP pruning, use the following command:

1912(config)# vtp pruning

Configuring VTP on a Set/Clear CLI Switch

Before you can configure a router or internal route processor for interVLAN routing, you must enable VTP, assign a mode, and configure a domain.

1.You enable and configure VTP and VLANs on the switch in Privileged mode. To enable VTP and specify a VTP mode, use the set vtp mode {client | server | transparent} command, as follows:

5002> (enable) set vtp mode server VTP domain modified

2.If you set the mode to client or server, then you need to set the VTP domain name and password on the first switch. The VTP name can be up to 32 characters long. The password is a minimum of 8 characters with a maximum of 64. For our example, we set the mode to server. The following shows the available syntaxes for the set vtp domain option:

5002> (enable) set vtp domain ?

Usage: set vtp [domain <name>] [mode <mode>] [passwd <passwd>] [pruning <enable|disable>] [v2 <enable|disable>

(mode = client|server|transparent

Use passwd Ô0’ to clear vtp password) Usage: set vtp pruneeligible <vlans>

(vlans = 2..1000

An example of vlans is 2−10,1000)

You must configure a VTP domain name if you choose to configure the switch as a VTP client or server. To do so, use the set vtp domain name command, as follows:

5002> (enable) set vtp domain Coriolis VTP domain Coriolis modified

3. Set the password to “pass1” for the VTP domain with the following command:

5002> (Enable) set vtp passwd pass1

Configuring VTP on a 1900 Cisco IOS CLI Switch

The 1900 switch does not require you to set the VTP password, just the domain name. The following shows the options available for the vtp domain command:

Here is an example of setting the domain to “Coriolis” on the 1912EN:

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