Catalyst 6500 Series Quick Software Configuration, 7.x
Configuring VLANs
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Table Of Contents

Configuring VLANs

Configuring VLAN Trunking Protocol

Configuring the Switch as a VTP Server

Configuring the Switch as a VTP Client

Configuring the Switch as VTP Transparent

Configuring VLANs

Creating VLANs

Assigning Switch Ports to VLANs

Configuring VLAN Trunks


Configuring VLANs

To configure VLANs on your Catalyst 6000 family switch, perform these steps:

Step 1 Configuring VLAN Trunking Protocol—Create a VLAN Trunking Protocol (VTP) domain and set the VTP mode on the switch.

Step 2 Configuring VLANs—Create VLANs in the VTP domain and place the switch ports in those VLANs.

Step 3 Configuring VLAN Trunks—Configure trunk ports between switches to transport traffic from multiple VLANs.

Configuring VLAN Trunking Protocol

VTP propagates information about the VLAN configuration throughout the switched network. A Catalyst 6000 family switch can operate in any one of these three VTP modes:

•Server—VTP servers advertise their VLAN configuration to other switches in the same VTP domain and synchronize their VLAN configuration with other switches based on advertisements received over trunk links. The VTP server is the default mode.

•Client—VTP clients are similar to VTP servers, except that you cannot create, change, or delete VLANs on a VTP client.

•Transparent—VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements.

Note Before you configure VLANs on the switch, you should decide whether to use VTP. If you choose to use VTP, decide if the switch should function as a VTP client or a VTP server. If you are connecting the switch to an existing network, make sure your VTP configuration is compatible with the rest of the network.

Configuring the Switch as a VTP Server

When you configure a switch as a VTP server, you must define a VTP domain before you can create VLANs.

To configure a switch as a VTP server, perform this task in privileged mode:

 
Task
Command

Step 1 

Assign a name to the VTP management domain.

set vtp domain name

Step 2 

Set the VTP mode.

set vtp mode server

Step 3 

Verify the VTP configuration.

show vtp domain

This example shows how to configure a switch as a VTP server: 

Console> (enable) set vtp domain BigCorp

VTP domain BigCorp modified

Console> (enable) set vtp mode server

VTP domain BigCorp modified

Console> (enable) show vtp domain

Domain Name                      Domain Index VTP Version Local Mode  Password

-------------------------------- ------------ ----------- ----------- ----------

BigCorp                          1            2           server      -


Vlan-count Max-vlan-storage Config Revision Notifications

---------- ---------------- --------------- -------------

9          1023             0               enabled


Last Updater    V2 Mode  Pruning  PruneEligible on Vlans

--------------- -------- -------- -------------------------

172.20.52.40    disabled disabled 2-1000

Console> (enable)

Configuring the Switch as a VTP Client

When you configure a switch as a VTP client, you cannot configure VLANs on the switch; instead, you configure VLANs on a VTP server in the same VTP domain as the client. The VTP client synchronizes its VLAN configuration to the configuration of the server.

To configure a switch as a VTP client, perform this task in privileged mode:

 
Task
Command

Step 1 

Assign a name to the VTP management domain.

set vtp domain name

Step 2 

Set the VTP mode.

set vtp mode client

Step 3 

Verify the VTP configuration. (It might take a few minutes before a VTP client learns the VTP and VLAN configuration information from neighboring switches.)

show vtp domain

This example shows how to configure a switch as a VTP client: 

Console> (enable) set vtp domain BigCorp

VTP domain BigCorp modified

Console> (enable) set vtp mode client

VTP domain BigCorp modified

Console> (enable) show vtp domain

Domain Name                      Domain Index VTP Version Local Mode  Password

-------------------------------- ------------ ----------- ----------- ----------

BigCorp                          1            2           client      -


Vlan-count Max-vlan-storage Config Revision Notifications

---------- ---------------- --------------- -------------

9          1023             0               enabled


Last Updater    V2 Mode  Pruning  PruneEligible on Vlans

--------------- -------- -------- -------------------------

172.20.52.40    disabled disabled 2-1000

Console> (enable)

Configuring the Switch as VTP Transparent

When you configure a switch as VTP transparent, you must configure VLAN information manually on the switch. A VTP-transparent switch does not advertise VLAN information to other switches and will ignore VTP updates from VTP clients and servers.

To configure a switch for VTP transparent mode, perform this task in privileged mode:

 
Task
Command

Step 1 

Set the VTP mode.

set vtp mode transparent

Step 2 

Verify the VTP configuration.

show vtp domain

This example shows how to configure a switch as VTP transparent: 

Console> (enable) set vtp mode transparent

VTP domain modified

Console> (enable) show vtp domain

Domain Name                      Domain Index VTP Version Local Mode  Password

-------------------------------- ------------ ----------- ----------- ----------

                                 1            2           Transparent -


Vlan-count Max-vlan-storage Config Revision Notifications

---------- ---------------- --------------- -------------

9          1023             0               enabled


Last Updater    V2 Mode  Pruning  PruneEligible on Vlans

--------------- -------- -------- -------------------------

172.20.52.40    disabled disabled 2-1000

Console> (enable)

Configuring VLANs

When you properly configure a switch for VTP, you can create, modify, and delete VLANs on the switch (unless you configured the switch as a VTP client). When you configure a VLAN on a VTP server, the configuration information is distributed to switches throughout the VTP domain.

VTP clients and servers in the same domain update their VLAN configuration based on the advertised configuration. VTP transparent switches do not act on VTP updates; you must make changes to the VLAN configuration locally on such switches.

Typically, in an IP network, each VLAN is associated with a single IP subnetwork. That is, all of the hosts in a given VLAN belong to a single subnet, use the same subnet mask, and use one or more default gateways connected to that subnetwork. Stations in different VLANs cannot communicate with one another without either a router configured to route between the different VLANs or manually configured (static) routes configured on the switches.

The Catalyst 6000 family software supports many VLAN types, including Ethernet, FDDI, ATM, and Token Ring.

Note Two Token Ring VLAN types are supported on switches running VTP version 2: Token Ring TrBRF VLANs and Token Ring TrCRF VLANs. Catalyst 6000 family switches do not support ISL-encapsulated Token Ring frames.

This section describes how to configure Ethernet VLANs only. For information about configuring other types of VLANs, refer to the Catalyst 6000 Family Software Configuration Guide.

Creating VLANs

To configure an Ethernet VLAN in a VTP domain, perform this task in privileged mode:

 
Task
Command

Step 1 

Create a VLAN by assigning it a VLAN number and, if desired, a VLAN name.

set vlan vlan_num [name name]

Step 2 

Verify the VLAN configuration.

show vlan vlan_num

This example shows how to create a VLAN and verify the VLAN configuration: 

Console> (enable) set vlan 100 name Pubs

Vlan 100 configuration successful

Console> (enable) show vlan 100

VLAN Name                             Status    Mod/Ports, Vlans

---- -------------------------------- --------- ----------------------------

100  Pubs                             active



VLAN Type  SAID       MTU   Parent RingNo BrdgNo Stp  BrdgMode Trans1 Trans2

---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------

100  enet  100100     1500  -      -      -      -    -        0      0



VLAN AREHops STEHops Backup CRF

---- ------- ------- ----------

Console> (enable)

Assigning Switch Ports to VLANs

After you create a VLAN, you can assign one or more switch ports to the VLAN. Devices connected to those ports will belong to that VLAN. Make sure the connected device is properly configured with an IP address, subnet mask, and default gateway in the subnet used for the VLAN.

To add a switch port to a VLAN, perform this task in privileged mode:

 
Task
Command

Step 1 

Add one or more switch ports to a VLAN.

set vlan vlan_num mod_num/port_num

Step 2 

Verify that the ports are properly assigned to the VLAN.

show vlan vlan_num

Step 3 

Check to which VLAN a particular port belongs.

show port [mod_num/port_num]

This example shows how to assign ports to a VLAN and how to verify to which VLAN the ports belong: 

Console> (enable) set vlan 100 2/1-4

VLAN 100 modified.

VLAN 1 modified.

VLAN  Mod/Ports

---- -----------------------

100   2/1-4


Console> (enable) show vlan 100

VLAN Name                             Status    Mod/Ports, Vlans

---- -------------------------------- --------- ----------------------------

100  Pubs                             active    2/1-4



VLAN Type  SAID       MTU   Parent RingNo BrdgNo Stp  BrdgMode Trans1 Trans2

---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------

100  enet  100100     1500  -      -      -      -    -        0      0



VLAN AREHops STEHops Backup CRF

---- ------- ------- ----------



Console> (enable) show port 2

Port  Name               Status     Vlan       Level  Duplex Speed Type

----- ------------------ ---------- ---------- ------ ------ ----- ------------

 2/1                     notconnect 100        normal   half   100 100BaseTX

 2/2                     notconnect 100        normal   half   100 100BaseTX

 2/3                     notconnect 100        normal   half   100 100BaseTX

 2/4                     notconnect 100        normal   half   100 100BaseTX

 2/5                     notconnect 1          normal   half   100 100BaseTX

<... output truncated ...>

Console> (enable)

Configuring VLAN Trunks

VLAN trunks are point-to-point links that carry the traffic of multiple VLANs. Trunk ports are useful in the network backbone, where traffic from many VLANs is handled.

All Ethernet ports can use Inter-Switch Link (ISL) or IEEE 802.1Q encapsulation for trunking.

By default, all Ethernet ports are set to negotiate and attempt to use ISL encapsulation.

If the port on the other end of the link is set to desirable or on, a port set to auto automatically becomes a trunk port. (For complete information on the various trunk modes and encapsulation types, refer to the Catalyst 6000 Family Software Configuration Guide.)

To configure an Ethernet port as a trunk, perform this task in privileged mode:

 
Task
Command

Step 1 

Configure a port as a trunk. A message appears on the console indicating that the port has become a trunk.

set trunk mod_num/port_num {on | desirable | auto} {isl | dot1q | negotiate}

Step 2 

Verify that the trunk configuration is correct.

show trunk

This example shows how to configure a port to become a trunk and how to verify the trunk configuration (this example assumes that the port on the other end of the link is set to auto): 

Console> (enable) set trunk 1/2 desirable

Port(s) 1/2 trunk mode set to desirable.

Console> (enable) 07/22/1998,10:16:58:DTP-5:Port 1/2 has become isl trunk

07/22/1998,10:16:58:PAGP-5:Port 1/2 left bridge port 1/2.

07/22/1998,10:17:09:PAGP-5:Port 1/2 joined bridge port 1/2.

Console> (enable) show trunk 1/2

Port      Mode         Encapsulation  Status        Native vlan

--------  -----------  -------------  ------------  -----------

 1/2      desirable    isl            trunking      523

Port      Vlans allowed on trunk

--------  ---------------------------------------------------------------------

 1/2      1-1005

Port      Vlans allowed and active in management domain

--------  ---------------------------------------------------------------------

 1/2      1,10,105,152,521-524

Port      Vlans in spanning tree forwarding state and not pruned

--------  ---------------------------------------------------------------------

 1/2      1,10,105,152,521-524

Console> (enable)