Configuring VTP and Virtual LANs

Note For complete syntax and usage information for the commands described in this chapter, refer to the Catalyst 2900 Series XL Command Reference.

These sections describe how to configure VTP and VLANs on Catalyst 2900 series XL switches:

Understanding How VTP Works

Before you create VLANs, you must decide whether to use VTP in your network. With VTP, you can make configuration changes centrally on a single switch, such as a
Catalyst 2900 series XL, and have those changes automatically communicated to all the other switches in the network. Without VTP, you cannot send information about VLANs to other switches.

VTP is a Layer 2 messaging protocol that maintains VLAN configuration consistency by managing the addition, deletion, and renaming of VLANs on a network-wide basis. VTP minimizes misconfigurations and configuration inconsistencies that can cause several problems, such as duplicate VLAN names, incorrect VLAN-type specifications, and security violations.

Understanding the VTP Domain

A VTP domain (also called a VLAN management domain) is one switch or several interconnected switches sharing the same VTP domain. A switch is configured to be in only one VTP domain. You make global VLAN configuration changes for the domain by using the Cisco IOS command-line interface (CLI), Cisco Visual Switch Manager Software, or Simple Network Management Protocol (SNMP).

By default, a Catalyst 2900 series XL switch is in the no-management-domain state until it receives an advertisement for a domain over a trunk link or you configure a management domain. The default VTP mode is server mode, but VLANs are not propagated over the network until a management domain name is specified or learned.

If the switch receives a VTP advertisement over a trunk link, it inherits the management domain name and configuration revision number. The switch then ignores advertisements with a different management domain name or an earlier configuration revision number.

When you make a change to the VLAN configuration on a VTP server, the change is propagated to all switches in the VTP domain. VTP advertisements are transmitted out all trunk connections, including Inter-Switch Link (ISL), IEEE 802.1Q, IEEE 802.10, and ATM LAN Emulation (LANE).

If you configure a switch from VTP transparent mode, you can create and modify VLANs, but the changes are not transmitted to other switches in the domain, and they affect only the individual switch.

Upgrading the Switch Software

When you upgrade from a software version that supports VLANs but does not support VTP, such as Cisco IOS Release 11.2(8)SA3, to a version that does support VTP, ports that belong to a VLAN retain their VLAN membership, and VTP enters transparent mode. The domain name becomes UPGRADE, and VTP does not propagate the VLAN configuration to other switches.

If you want to propagate the VLAN configuration to other switches, configure the switch to operate as a VTP server, and change the domain name.

Understanding VTP Modes and VTP Mode Transitions

You can configure a Catalyst 2900 series XL switch to be in one of the following VTP modes :

VTP server ---In this mode, you can create, modify, and delete VLANs and specify other configuration parameters (such as VTP version) for the entire VTP domain. VTP servers advertise their VLAN configurations to other switches in the same VTP domain and synchronize their VLAN configurations with other switches based on advertisements received over trunk links.

: In VTP server mode, VLAN configurations are saved in nonvolatile memory. VTP server is the default mode.

VTP client ---In this mode, VTP clients behave like VTP servers, but you cannot create, change, or delete VLANs on a VTP client.

: In VTP client mode, VLAN configurations are not saved in nonvolatile memory.

VTP transparent ---In this mode , 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. However, transparent switches do forward VTP advertisements that they receive from other switches. You can create, modify, and delete VLANs.

: In VTP transparent mode, VLAN configurations are saved in nonvolatile memory, but they are not advertised to other switches.

Note Two configurations can cause a Catalyst 2900 series XL switch to automatically change VTP mode. When the network is configured with more than 64 VLANs, the Catalyst 2900 series XL switch automatically changes from VTP server or client mode to VTP transparent mode. The switch then operates with the VLAN configuration that preceded the one that sent it into transparent mode. When a multi-VLAN port is configured on a Catalyst 2900 series XL switch in VTP server mode or client mode, the switch automatically changes to transparent mode.

The "VTP Configuration Guidelines" section provides tips and caveats for configuring VTP.

Understanding VTP Advertisements

Each switch in the VTP domain sends these periodic global configuration advertisements from each trunk port to a reserved multicast address. Neighboring switches receive these advertisements and update their VTP and VLAN configurations as necessary.

The following global domain information is distributed in VTP advertisements:

VTP domain name
VTP configuration revision number
Update identity and update timestamp
MD5 digest

The following VLAN information is distributed in VTP advertisements for each configured VLAN:

VLAN ID
VLAN name
VLAN type
VLAN state
Additional VLAN configuration information specific to the VLAN type

Understanding VTP Version 2

If you use VTP in your network, you must decide whether to use VTP version 1 or version 2. If your environment has Token Ring networks, you must use version 2.

VTP version 2 supports the following features not supported in version 1:

Token Ring support---VTP version 2 supports Token Ring LAN switching and VLANs (Token Ring Bridge Relay Function [TrBRF] and Token Ring Concentrator Relay Function [TrCRF]). For more information about Token Ring VLANs, refer to the "Understanding How VLANs Work" section.
Unrecognized Type-Length-Value (TLV) support---A VTP server or client propagates configuration changes to its other trunks, even for TLVs it is not able to parse. The unrecognized TLV is saved in nonvolatile memory when the switch is operating in VTP server mode.
Version-Dependent Transparent Mode---In VTP version 1, a VTP transparent switch inspects VTP messages for the domain name and version and forwards a message only if the version and domain name match. Because only one domain is supported in the Enterprise Edition Software, VTP version 2 forwards VTP messages in transparent mode without checking the version and domain name.
Consistency Checks---In VTP version 2, VLAN consistency checks (such as VLAN names and values) are performed only when you enter new information through the CLI, the Cisco Visual Switch Manager Software, or SNMP. Consistency checks are not performed when new information is obtained from a VTP message or when information is read from nonvolatile memory. If the digest on a received VTP message is correct, its information is accepted without consistency checks.

Understanding VTP Pruning

Although Catalyst 2900 series XL ports are never eligible for VTP pruning, the switch does propagate VTP pruning messages. This section describes the role that a
Catalyst 2900 series XL switch can play in a VTP pruning network.

VTP pruning increases available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to access the appropriate network devices. When VTP pruning is enabled, it can block flooded traffic to VLANs that are included in the pruning-eligible list. No Catalyst 2900 series XL VLANs are in the pruning-eligible list, and no switch traffic is pruned. Flooding occurs as usual, and switches connected to the
Catalyst 2900 series XL switch do not benefit from pruning.

Figure 2-1 shows a switched network with VTP pruning enabled. The broadcast traffic from Switch 1 is not forwarded to Switches 5 and 6 because traffic for the Red VLAN has been pruned on the links indicated (port 4 on Switch 4). The Catalyst 2900 series switch does not prune the traffic destined for Switch 4 or Switch 3.

Note The Catalyst 2900 series XL will support VTP pruning eligibility list in a future release.

Figure 2-1: Flooding Traffic with VTP Pruning

VTP Configuration Guidelines

Follow these guidelines when implementing VTP in your network:

All switches in a VTP domain must run the same VTP version.
The password entered with a domain name should be the same for all switches in the domain.

: If you configure a VTP password, the management domain will not
function properly if you do not assign the management domain password to each
switch in the domain.

A VTP version 2-capable switch can operate in the same VTP domain as a switch running VTP version 1 provided version 2 is disabled on the version 2-capable switch (version 2 is disabled by default).

Do not enable VTP version 2 on a switch unless all of the switches in the same VTP domain are version 2-capable. When you enable version 2 on a switch, all of the version 2-capable switches in the domain enable version 2. If there is a version 1-only switch, it will not exchange VTP information with switches with version 2 enabled.

If there are token ring networks in your environment, you must enable VTP version 2 for Token Ring VLAN switching to function properly.

Enabling or disabling VTP pruning on a VTP server enables or disables VTP pruning for the entire management domain.

Default VTP Configuration

Table 2-1 shows the default VTP configuration.

Feature	Default Value
VTP domain name	Null.
VTP mode	Server.
VTP version 2 enable state	Version 2 is disabled.
VTP password	None.
VTP pruning	Disabled.

Table 2-1: VTP Default Configuration

Feature Default Value

VTP domain name

Null.

VTP mode

Server.

VTP version 2 enable state

Version 2 is disabled.

VTP password

None.

VTP pruning

Disabled.

Configuring VTP

You configure VTP by entering commands from the VLAN database configuration command mode. You display the status of VTP by entering the privileged EXEC mode show vtp status command.

When you enter the exit command in VLAN database mode, it applies all the commands that you entered. VTP messages are sent to other switches in the management domain, and you are returned to privileged EXEC mode.

For more information about these commands, refer to the Catalyst 2900 Series XL Command Reference.

Note The Cisco IOS end and Ctrl-Z commands are not supported in VLAN database mode.

Configuring a VTP Server

When a switch is in VTP server mode, you can change the VLAN configuration and have it propagate throughout the network. To configure the switch as a VTP server, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Configure a VTP administrative-domain name. This can be from 1 to 32 characters long.

vtp domain domain-name

Step 3 (Optional) Set a password for the VTP domain. The password can be from 8 to
64 characters long.

vtp password password-value

Step 4 Configure the switch as a server.

vtp server

Step 5 Return to privileged EXEC mode.

exit

Step 6 Verify the VTP configuration.

show vtp status

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Configure a VTP administrative-domain name. This can be from 1 to 32 characters long.	vtp domain domain-name
Step 3 (Optional) Set a password for the VTP domain. The password can be from 8 to 64 characters long.	vtp password password-value
Step 4 Configure the switch as a server.	vtp server
Step 5 Return to privileged EXEC mode.	exit
Step 6 Verify the VTP configuration.	show vtp status

This example shows how to enter a VTP domain name and configure the switch as a VTP server:

Switch# vlan database
Switch(vlan)# vtp domain Building_A
Setting VTP domain name to Building_A
Switch(vlan)# vtp domain Building_A password LAVA
Domain name already set to Building_A .
Setting device VLAN database password to LAVA.
Switch(vlan)# vtp server
Setting device to VTP SERVER mode.
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 68
Number of existing VLANs        : 6
 VTP Operating Mode              : Server
 VTP Domain Name                 : Building_A
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x09 0xF6 0x57 0x1C 0xC9 0x6F 0x75 0x16

Configuring a VTP Client

When a switch is in VTP client mode, you cannot change its VLAN configuration. The client switch receives VTP updates from a VTP server in the management domain and then modifies its configuration accordingly.

To configure the switch as a VTP client, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Place the switch in VTP client mode.

vtp client

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify the VTP configuration.

show vtp status

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Place the switch in VTP client mode.	vtp client
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify the VTP configuration.	show vtp status

This example shows how to configure the switch as a VTP client and verify the configuration:

Switch# vlan database
Switch(vlan)# vtp client
Setting device to VTP CLIENT mode.
 
Switch(vlan)# exit
In CLIENT state, no apply attempted.
Exiting....
 
Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 68
Number of existing VLANs        : 6

 VTP Operating Mode              : Client
VTP Domain Name                 : Building_A
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x09 0xF6 0x57 0x1C 0xC9 0x6F 0x75 0x16
Configuration last modified by 172.20.130.40 at 3-5-93 22:15:25

Disabling VTP

When you configure the switch as VTP transparent, you disable VTP on the switch. The switch then does not send VTP updates and does not act on VTP updates received from other switches. However, a VTP transparent switch does forward received VTP advertisements on all of its trunk links.

To put the switch in VTP transparent mode, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Place the switch in VTP transparent mode
(disabling VTP on the switch).

vtp transparent

Step 3 Return to privileged EXEC mode.

exit

Step 4 Verify the VTP configuration.

show vtp status

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Place the switch in VTP transparent mode (disabling VTP on the switch).	vtp transparent
Step 3 Return to privileged EXEC mode.	exit
Step 4 Verify the VTP configuration.	show vtp status

This example shows how to configure the switch as VTP transparent and verify the configuration:

Switch# vlan database
Switch(vlan)# vtp transparent
Setting device to VTP TRANSPARENT mode.
 
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 68
Number of existing VLANs        : 6

 VTP Operating Mode              : Transparent
VTP Domain Name                 : Building_A
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x09 0xF6 0x57 0x1C 0xC9 0x6F 0x75 0x16
Configuration last modified by 172.20.130.40 at 3-5-93 22:15:25

Enabling VTP Version 2

VTP version 2 is disabled by default on VTP version 2-capable switches. When you enable VTP version 2 on a switch, every VTP version 2-capable switch in the VTP domain enables version 2.

Caution VTP version 1 and VTP version 2 are not interoperable on switches in the same VTP domain. Every switch in the VTP domain must use the same VTP version. Do not enable VTP version 2 unless every switch in the VTP domain supports version 2.

Note In a Token Ring environment, you must enable VTP version 2 for Token Ring VLAN switching to function properly.

To enable VTP version 2, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Enable VTP version 2 on the switch.

vtp v2-mode

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify that VTP version 2 is enabled.

show vtp status

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Enable VTP version 2 on the switch.	vtp v2-mode
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify that VTP version 2 is enabled.	show vtp status

This example shows how to enable VTP version 2 and verify the configuration:

Switch# vlan database
Switch(vlan)# vtp v2-mode
V2 mode enabled.
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 2
Maximum VLANs supported locally : 68
Number of existing VLANs        : 14
VTP Operating Mode              : Server
VTP Domain Name                 : milano
VTP Pruning Mode                : Disabled

 VTP V2 Mode                     : Enabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0xAC 0x23 0x2F 0x75 0x52 0xDC 0x17 0x70
Configuration last modified by 172.20.128.178 at 3-6-93 23:46:53

Disabling VTP Version 2

To disable VTP version 2, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Disable VTP version 2.

no vtp v2-mode

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify that VTP version 2 is disabled.

show vtp status

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Disable VTP version 2.	no vtp v2-mode
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify that VTP version 2 is disabled.	show vtp status

This example shows how to disable VTP version 2:

Switch# vlan database
Switch(vlan)# no vtp v2-mode
V2 mode disabled.
Switch(vlan)# exit
In CLIENT state, no apply attempted.
Exiting....
 
Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 68
Number of existing VLANs        : 59
VTP Operating Mode              : Client
VTP Domain Name                 : milano
VTP Pruning Mode                : Disabled

 VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0x53 0x97 0x06 0x02 0xF8 0x6F 0x45 0x85
Configuration last modified by 172.20.128.151 at 3-5-93 01:05:21

Monitoring VTP

You monitor VTP by displaying its configuration information: the domain name, the current VTP revision, and the number of VLANs. You can also display statistics about the advertisements sent and received by the switch.

To monitor VTP activity perform this task from privileged EXEC mode:

Task Command

Step 1 Display the VTP switch configuration information.

show vtp status

Step 2 Display counters about VTP messages being sent and received.

show vtp counters

Task	Command
Step 1 Display the VTP switch configuration information.	show vtp status
Step 2 Display counters about VTP messages being sent and received.	show vtp counters

This example shows how to display the switch VTP status:

Switch# show vtp status
VTP Version                     : 2
Configuration Revision          : 2
Maximum VLANs supported locally : 68
Number of existing VLANs        : 6
VTP Operating Mode              : Transparent
VTP Domain Name                 : Building_A
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
MD5 digest                      : 0xB9 0xC7 0x8D 0xB3 0xD4 0xBA 0x94 0x03
Configuration last modified by 172.20.130.40 at 3-9-93 20:12:24

This example shows how to display the VTP statistics:

Switch# show vtp counters
VTP statistics:
Summary advertisements received    : 3
Subset advertisements received     : 2
Request advertisements received    : 0
Summary advertisements transmitted : 10
Subset advertisements transmitted  : 10
Request advertisements transmitted : 1
Number of config revision errors   : 0
Number of config digest errors     : 0
Number of V1 summary errors        : 0
 
VTP pruning statistics:
 
Trunk            Join Transmitted Join Received    Summary advts received from
                                                   non-pruning-capable device
---------------- ---------------- ---------------- ---------------------------
Fa1/1               8                6                0        
Fa1/2               6                0                0        
Fa1/3               6                0                0        
Fa1/4               6                0                0

Understanding How VLANs Work

A VLAN is a group of end stations with a common set of requirements, independent of physical location. VLANs have the same attributes as a physical LAN but allow you to group end stations even if they are not physically located on the same LAN segment.

VLANs on Catalyst 2900 series XL switches and other supported devices limit unicast, multicast, and broadcast traffic flooding. Flooded traffic originating from a particular VLAN is only flooded out other ports belonging to that VLAN.

Understanding VLAN Membership

Ports that belong to VLANs are configured with a membership mode that determines what kind of traffic each port carries and how many VLANs it can belong to. Table 2-2 lists the membership modes and characteristics.

Table 2-2: Port Membership Modes
Membership Mode VLAN Membership Characteristics

Static-access

Can belong to one VLAN and is manually assigned. This is the default.

Multi-VLAN

Can belong to up to 64 VLANs and is manually assigned. A multi-VLAN port cannot be configured when there is a trunk configured on the switch. VLAN traffic on the multi-VLAN port is not encapsulated.

Dynamic access

Can belong to one VLAN and is dynamically assigned by a VLAN Membership Policy Server (VMPS).

Trunk (ISL or IEEE 802.1Q)

A trunk is a member of all VLANs in the VLAN database by default, but membership can be limited by configuring the allowed-VLAN list.

**Table 2-2: Port Membership Modes**
Membership Mode	VLAN Membership Characteristics
Static-access	Can belong to one VLAN and is manually assigned. This is the default.
Multi-VLAN	Can belong to up to 64 VLANs and is manually assigned. A multi-VLAN port cannot be configured when there is a trunk configured on the switch. VLAN traffic on the multi-VLAN port is not encapsulated.
Dynamic access	Can belong to one VLAN and is dynamically assigned by a VLAN Membership Policy Server (VMPS).
Trunk (ISL or IEEE 802.1Q)	A trunk is a member of all VLANs in the VLAN database by default, but membership can be limited by configuring the allowed-VLAN list.

Understanding VLANs in a VTP Domain

Before you create VLANs, you must decide whether to use VTP to maintain global VLAN configuration information for your network. For complete information on VTP, refer to the "Understanding How VTP Works" section .

Figure 2-2 shows an example of VLANs segmented into logically defined networks.

VLANs are often associated with IP subnetworks. For example, all the end stations in a particular IP subnet belong to the same VLAN. Traffic between VLANs must be routed. Port VLAN membership on the switch is assigned manually on a port-by-port basis. When you assign switch ports to VLANs using this method, it is known as port-based, or static, VLAN membership.

Figure 2-2: VLANs as Logically Defined Networks

You can set the following parameters when you add a VLAN to a VTP database:

VLAN ID
VLAN name
VLAN type (Ethernet, Fiber Distributed Data Interface [FDDI], FDDI network entity title [NET], TrBRF, or TrCRF)
VLAN state (active or suspended)
Maximum transmission unit (MTU) for the VLAN
Security Association Identifier (SAID)
Bridge identification number for TrBRF VLANs
Ring number for FDDI and TrCRF VLANs
Parent VLAN number for TrCRF VLANs
Spanning-Tree Protocol (STP) type for TrCRF VLANs
VLAN number to use when translating from one VLAN type to another

The "Default VLAN Configurations" section lists the default values and possible ranges for each VLAN media type.

Understanding Token Ring VLANs

Although the Catalyst 2900 series XL does not support Token Ring connections, a remote device such as a Catalyst 5000 series switch with Token Ring connections could be managed from the Catalyst 2900 series XL switch. A Catalyst 2900 series XL switch advertises information about Token Ring VLANs when running VTP version 2. The following Token Ring VLAN types are supported on Catalyst 2900 series XL switches running VTP version 2:

Token Ring TrBRF VLANs
Token Ring TrCRF VLANs

For more information on configuring Token Ring VLANs, see the Catalyst 5000 Series Software Configuration Guide.

VLAN Configuration Guidelines

Follow these guidelines when creating and modifying VLANs in your network:

A maximum of 64 VLANs can be active on a Catalyst 2900 series XL switch. VTP can indicate that there are 68 active VLANs, but 4 of these (1002-1005) are reserved for Token Ring and FDDI and cannot be active on a Catalyst 2900 series XL switch.
Before you can create a VLAN, the switch must be in VTP server mode or VTP transparent mode. For information on configuring VTP, refer to the "Configuring VTP" section.
The Catalyst 2900 series XL does not support Token Ring or FDDI media. The switch does not forward FDDI, FDDI-Net, TrCRF, or TrBRF traffic, but it does propagate the VLAN configuration via VTP.

Default VLAN Configurations

Table 2-3 through Table 2-7 shows the default configurations for the different VLAN media types.

Note Catalyst 2900 series XL switches only support Ethernet interfaces. You only configure FDDI and Token Ring media-specific characteristics for VLAN Trunk Protocol (VTP) global advertisements to other switches. These VLANs are not locally supported.

Parameter	Default	Range
VLAN ID	1	1-1005
VLAN name	VLANxxxx, where xxxx is the VLAN ID	No range
802.10 SAID	100000+VLAN ID	1-4294967294
MTU size	1500	1500-18190
Translational bridge 1	0	0-1005
Translational bridge 2	0	0-1005
VLAN state	active	active, suspend

Parameter	Default	Range
VLAN ID	1002	1-1005
VLAN name	VLANxxxx, where xxxx is the VLAN ID	No range
802.10 SAID	100000+VLAN ID	1-4294967294
MTU size	1500	1500-18190
Translational bridge 1	0	0-1005
Translational bridge 2	0	0-1005
VLAN state	active	active, suspend

Parameter	Default	Range
VLAN ID	1004	1-1005
VLAN name	VLANxxxx, where xxxx is the VLAN ID	No range
802.10 SAID	100000+VLAN ID	1-4294967294
MTU size	1500	1500-18190
Bridge number	0	0-15
STP type	ibm	auto, ibm, ieee
Translational bridge 1	0	0-1005
Translational bridge 2	0	0-1005
VLAN state	active	active, suspend

Parameter	Default	Range
VLAN ID	1005	1-1005
VLAN name	VLANxxxx, where xxxx is the VLAN ID	No range
802.10 SAID	100000+VLAN ID	1-4294967294
MTU size	VTPv1 1500; VTPv2 4472	1500-18190
Bridge number	VTPv1 0; VTPv2 user-specified	0-15
STP type	ibm	auto, ibm, ieee
Translational bridge 1	0	0-1005
Translational bridge 2	0	0-1005
VLAN state	active	active, suspend

Parameter	Default	Range
VLAN ID	1003	1-1005
VLAN name	VLANxxxx, where xxxx is the VLAN ID	No range
802.10 SAID	100000+VLAN ID	1-4294967294
Ring Number	VTPv1 default 0; VTPv2 user-specified	1-4095
Parent VLAN	VTPv1 default 0; VTPv2 user-specified	0-1005
MTU size	VTPv1 default 1500; VTPv2 default 4472	1500-18190
Translational bridge 1	0	0-1005
Translational bridge 2	0	0-1005
VLAN state	active	active, suspend
Bridge mode	srb	srb, srt
ARE max hops	7	0-13
STE max hops	7	0-13
Backup CRF	disabled	disable; enable

Table 2-7:

Parameter Default Range

VLAN ID

1003

1-1005

VLAN name

VLANxxxx, where xxxx is the VLAN ID

No range

802.10 SAID

100000+VLAN ID

1-4294967294

Ring Number

VTPv1 default 0; VTPv2 user-specified

1-4095

Parent VLAN

VTPv1 default 0; VTPv2 user-specified

0-1005

MTU size

VTPv1 default 1500; VTPv2 default 4472

1500-18190

Translational bridge 1

0

0-1005

Translational bridge 2

0

0-1005

VLAN state

active

active, suspend

Bridge mode

srb

srb, srt

ARE max hops

7

0-13

STE max hops

7

0-13

Backup CRF

disabled

disable; enable

Token Ring (TrCRF) VLAN Defaults and Ranges

Configuring VLANs

You use the VLAN database command mode to add, change, and delete VLANs. In VTP server or transparent mode, these commands are written to the file vlan.dat and can be displayed by entering the privileged EXEC mode show vlan command. The vlan.dat file is stored in nonvolatile memory.

Caution You can cause inconsistency in the VLAN database if you attempt to manually delete the vlan.dat file. If you want to modify the VLAN configuration or VTP, use the VLAN database commands described in the Catalyst 2900 Series XL Command Reference.

You use the interface configuration command mode to define the port membership mode and add and remove ports from VLAN. The results of these command are written to the running-configuration file and can be displayed by entering the privileged EXEC mode show running-config command.

Note VLANs can be configured to support a number of parameters that are not discussed in detail in this section. For complete information on the commands and parameters that control VLAN configuration, refer to the Catalyst 2900 Series XL Command Reference.

Adding an Ethernet VLAN

Each VLAN has a unique, four-digit ID that can be a number from 1 to 1001. To add a VLAN to the VLAN database, assign a number and name to the VLAN. See the "Default VLAN Configurations" section for the list of default parameters that are assigned when you add a VLAN.

If you do not specify the VLAN type, the VLAN is an Ethernet VLAN. To add a VLAN, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Add an Ethernet VLAN by assigning a number to it. If no name is entered for the VLAN, the default is to append the vlan-id to the word VLAN. For example, VLAN0004 could be a default VLAN name.

vlan vlan-id name vlan-name

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify the VLAN configuration.

show vlan name vlan-name

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Add an Ethernet VLAN by assigning a number to it. If no name is entered for the VLAN, the default is to append the vlan-id to the word VLAN. For example, VLAN0004 could be a default VLAN name.	vlan vlan-id name vlan-name
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify the VLAN configuration.	show vlan name vlan-name

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

Switch# vlan database
Switch(vlan)# vlan 0003 name marketing
VLAN 3 added:
    Name: marketing
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vlan name marketing
VLAN Name                             Status    Ports
---- -------------------------------- --------- ---------------------
3    marketing                        active
 
VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- ------ ------
3    enet  100003     1500  -      -      -        -    0      0

Modifying an Ethernet VLAN

To modify the VLAN parameters on an existing Ethernet VLAN, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Identify the VLAN, and change the MTU size.

vlan vlan-id mtu mtu-size

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify the VLAN configuration.

show vlan vlan-id

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Identify the VLAN, and change the MTU size.	vlan vlan-id mtu mtu-size
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify the VLAN configuration.	show vlan vlan-id

This example shows how to modify an Ethernet VLAN and verify the configuration:

Switch# vlan database
Switch(vlan)# vlan 0003 mtu 4000
VLAN 3 modified:
    MTU 4000
 
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vlan 0003
 
VLAN Type  SAID       MTU   Parent RingNo BridgeNo Stp  Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- ------ ------
3    enet  100003     4000  -      -      -        -    0      0

Deleting a VLAN from the Database

When you delete a VLAN from a switch that is in VTP server mode, the VLAN is removed from all switches in the VTP domain. When you delete a VLAN from a switch that is in VTP transparent mode, the VLAN is deleted only on that specific switch.

You cannot delete the default VLANs for the different media types: VLAN 1 and 1002-1005.

Caution When you delete a VLAN, any ports assigned to that VLAN become inactive. Such ports remain associated with the VLAN (and thus inactive) until you assign them to a new VLAN.

To delete a VLAN on the switch, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter VLAN configuration mode.

vlan database

Step 2 Remove the VLAN by using the VLAN ID.

no vlan vlan-id

Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.

exit

Step 4 Verify the VLAN removal.

show vlan brief

Task	Command
Step 1 Enter VLAN configuration mode.	vlan database
Step 2 Remove the VLAN by using the VLAN ID.	no vlan vlan-id
Step 3 Update the VLAN database, propagate it throughout the administrative domain, and return to privileged EXEC mode.	exit
Step 4 Verify the VLAN removal.	show vlan brief

This example shows how to delete a VLAN:

Switch# vlan database
Switch(vlan)# no vlan 3
Deleting VLAN 3...
Switch(vlan)# exit
APPLY completed.
Exiting....
 
Switch# show vlan brief
VLAN Name                             Status    Ports
---- -------------------------------- --------- ---------------------
1    default                          active    Fa0/2, Fa0/3, Fa0/4, Fa0/5,
                                                Fa0/6, Fa0/7, Fa0/8, Fa0/9,
                                                Fa0/10, Fa0/11, Fa0/12, Fa0/13,
                                                Fa0/14, Fa0/15, Fa0/16
2    VLAN0002                         active
4    VLAN0004                         active
1002 fddi-default                     active
1003 token-ring-default               active
1004 fddinet-default                  active
1005 trnet-default                    active

Assigning Static-Access Ports to a VLAN

A static-access port belongs to one VLAN. To assign a port to a VLAN, perform this task from privileged EXEC mode:

Task Command

Step 1 Enter global configuration mode

configure terminal

Step 2 Enter interface configuration mode, and define the interface to be added to the VLAN.

interface interface

Step 3 Define the VLAN membership mode for this port.

switchport mode access

Step 4 Assign the port to the VLAN

switchport access vlan 3

Step 5 Return to privileged EXEC mode.

end

Step 6 Verify the VLAN configuration.

show interface interface-id switchport

Task	Command
Step 1 Enter global configuration mode	configure terminal
Step 2 Enter interface configuration mode, and define the interface to be added to the VLAN.	interface interface
Step 3 Define the VLAN membership mode for this port.	switchport mode access
Step 4 Assign the port to the VLAN	switchport access vlan 3
Step 5 Return to privileged EXEC mode.	end
Step 6 Verify the VLAN configuration.	show interface interface-id switchport

This example shows how to assign switch ports to a VLAN and verify the assignment:

Switch# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Switch(config)# interface fa0/1
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 0003
Switch(config-if)# end
 
Switch# show interface fa0/1 switchport
Name: Fa0/1
Switchport: Enabled
Administrative mode: static access

 Operational Mode: static access
Administrative Trunking Encapsulation: isl
Operational Trunking Encapsulation: isl
Negotiation of Trunking: Disabled

 Access Mode VLAN: 3 (marketing)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: NONE
Pruning VLANs Enabled: NONE

Table of Contents

Configuring VTP and Virtual LANs