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This chapter describes how to configure VLAN Trunk Protocol (VTP), Generic Attribute Registration Protocol (GARP; see IEEE 802.1P), GARP VLAN Registration Protocol (GVRP; see IEEE 802.1P), and virtual LANs (VLANs).
This chapter consists of these sections:
These sections describe how to use VTP with the Catalyst 6000 and 6500 series switches:
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 Catalyst series switch and have those changes automatically communicated to all the other switches in the network.
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 result in a number of problems, such as duplicate VLAN names, incorrect VLAN-type specifications, and security violations.
These sections describe how VTP works on the Catalyst 6000 and 6500 series switches:
A VTP domain (also called a VLAN management domain) is made up of one or more interconnected switches that share the same VTP domain name. A switch can be configured to be in only one VTP domain. You make global VLAN configuration changes for the domain using either the command-line interface (CLI) or Simple Network Management Protocol (SNMP).
By default, a Catalyst 6000 or 6500 series switch is in VTP server mode and is in the no-management domain state until the switch receives an advertisement for a domain over a trunk link or you configure a management domain. You cannot create or modify VLANs on a VTP server until the 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 ignores advertisements with a different management domain name or an earlier configuration revision number.
If you configure the switch as VTP transparent, you can create and modify VLANs but the changes affect only the individual switch.
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).
VTP maps VLANs dynamically across multiple LAN types with unique names and internal index associations. Mapping eliminates excessive device administration required from network administrators.
You can configure a Catalyst 6000 or 6500 series switch to operate in any one of these VTP modes:
Each switch in the VTP domain sends periodic advertisements out each trunk port to a reserved multicast address. VTP advertisements are received by neighboring switches, which update their VTP and VLAN configurations as necessary.
The following global configuration information is distributed in VTP advertisements:
If you use VTP in your network, you must decide whether to use VTP version 1 or version 2. Catalyst 6000 and 6500 series switches support both versions.
VTP version 2 supports the following features not supported in version 1:
VTP pruning enhances network bandwidth use by reducing unnecessary flooded traffic, such as broadcast, multicast, unknown, and flooded unicast packets. VTP pruning increases available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to access the appropriate network devices. By default, VTP pruning is disabled.
Make sure that all devices in the management domain support VTP pruning before enabling it. VTP pruning is supported in the Catalyst 6000 and 6500 series software releases.
Figure 8-1 shows a switched network without VTP pruning enabled. Port 1 on Switch 1 and port 2 on Switch 4 are assigned to the Red VLAN. A broadcast is sent from the host connected to Switch 1. Switch 1 floods the broadcast and every switch in the network receives it, even though Switches 3, 5, and 6 have no ports in the Red VLAN.
Figure 8-2 shows the same switched network with VTP pruning enabled. The broadcast traffic from Switch 1 is not forwarded to Switches 3, 5, and 6 because traffic for the Red VLAN has been pruned on the links indicated (port 5 on Switch 2 and port 4 on Switch 4).
Enabling VTP pruning on a VTP server enables pruning for the entire management domain. VTP pruning takes effect several seconds after you enable it. By default, VLANs 2 through 1000 are pruning-eligible. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VLAN 1 is always pruning-ineligible; traffic from VLAN 1 cannot be pruned.
To make a VLAN pruning ineligible, enter the clear vtp pruneeligible command. To make a VLAN pruning eligible again, enter the set vtp pruneeligible command. You can set VLAN pruning-eligibility regardless of whether VTP pruning is enabled or disabled for the domain. Pruning eligibility always applies to the local device only, not for the entire VTP domain.
Table 8-1 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 |
Follow these guidelines when implementing VTP in your network:
| Caution If you configure VTP in secure mode, the management domain will not function properly if you do not assign a management domain password to each switch in the domain. |
These sections describe how to configure VTP on the Catalyst 6000 and 6500 series switches:
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 in privileged mode:
| Task | Command |
|---|---|
Step 1 Define the VTP domain name. | set vtp domain name |
Step 2 Place the switch in VTP server mode. | set vtp mode server |
Step 3 (Optional) Set a password for the VTP domain. | set vtp passwd passwd |
Step 4 Verify the VTP configuration. | show vtp domain |
This example shows how to configure the switch as a VTP server and verify the configuration:
Console> (enable) set vtp domain Lab_Network VTP domain Lab_Network modified Console> (enable) set vtp mode server VTP domain Lab_Network modified Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode Password -------------------------------- ------------ ----------- ----------- ---------- Lab_Network 1 2 server - Vlan-count Max-vlan-storage Config Revision Notifications ---------- ---------------- --------------- ------------- 10 1023 40 enabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- -------- -------- ------------------------- 172.20.52.70 disabled disabled 2-1000 Console> (enable)
When a switch is in VTP client mode, you cannot change the VLAN configuration on the switch. The client switch receives VTP updates from a VTP server in the management domain and modifies its configuration accordingly.
To configure the switch as a VTP client, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Define the VTP domain name. | set vtp domain name |
Step 2 Place the switch in VTP client mode. | set vtp mode client |
Step 3 Verify the VTP configuration. | show vtp domain |
This example shows how to configure the switch as a VTP client and verify the configuration:
Console> (enable) set vtp domain Lab_Network VTP domain Lab_Network modified Console> (enable) set vtp mode client VTP domain Lab_Network modified Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode Password -------------------------------- ------------ ----------- ----------- ---------- Lab_Network 1 2 client - Vlan-count Max-vlan-storage Config Revision Notifications ---------- ---------------- --------------- ------------- 10 1023 40 enabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- -------- -------- ------------------------- 172.20.52.70 disabled disabled 2-1000 Console> (enable)
When you configure the switch as VTP transparent, you disable VTP on the switch. A VTP transparent switch does not send VTP updates and does not act on VTP updates received from other switches. However, a VTP transparent switch running VTP version 2 does forward received VTP advertisements out all of its trunk links.
To disable VTP on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Place the switch in VTP transparent mode (disabling VTP on the switch). | set vtp mode transparent |
Step 2 Verify the VTP configuration. | show vtp domain |
This example shows how to configure the switch as VTP transparent and verify the configuration:
Console> (enable) set vtp mode transparent VTP domain Lab_Net modified Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode Password -------------------------------- ------------ ----------- ----------- ---------- Lab_Net 1 2 Transparent - Vlan-count Max-vlan-storage Config Revision Notifications ---------- ---------------- --------------- ------------- 10 1023 0 enabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- -------- -------- ------------------------- 172.20.52.70 disabled disabled 2-1000 Console> (enable)
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 also 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. |
To enable VTP version 2, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Enable VTP version 2 on the switch. | set vtp v2 enable |
Step 2 Verify that VTP version 2 is enabled. | show vtp domain |
This example shows how to enable VTP version 2 and verify the configuration (shown by the arrow):
Console> (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 Lab_Net modified Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode Password -------------------------------- ------------ ----------- ----------- ---------- Lab_Net 1 2 server - Vlan-count Max-vlan-storage Config Revision Notifications ---------- ---------------- --------------- ------------- 10 1023 1 enabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- -------- -------- -------------------------
172.20.52.70 enabled disabled 2-1000 Console> (enable)
To disable VTP version 2, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Disable VTP version 2. | set vtp v2 disable |
Step 2 Verify that VTP version 2 is disabled. | show vtp domain |
This example shows how to disable VTP version 2:
Console> (enable) set vtp v2 disable This command will disable the version 2 function in the entire management domain. Warning: trbrf & trcrf vlans will not work properly in this mode. Do you want to continue (y/n) [n]? y VTP domain Lab_Net modified Console> (enable)
To configure VTP pruning, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Enable VTP pruning in the management domain. | set vtp pruning enable |
Step 2 (Optional) Make specific VLANs pruning-ineligible on the device. (By default, VLANs 2-1000 are pruning-eligible.) | clear vtp pruneeligible vlan_range |
Step 3 (Optional) Make specific VLANs pruning-eligible on the device. | set vtp pruneeligible vlan_range |
Step 4 Verify the VTP pruning configuration. | show vtp domain |
Step 5 Verify that the appropriate VLANs are being pruned on trunk ports. | show trunk |
This example shows how to enable VTP pruning in the management domain and how to make VLANs 2-99, 250-255, and 501-1000 pruning-eligible on the particular device:
Console> (enable) set vtp pruning enable This command will enable the pruning function in the entire management domain. All devices in the management domain should be pruning-capable before enabling. Do you want to continue (y/n) [n]? y VTP domain Lab_Network modified Console> (enable) clear vtp pruneeligible 100-500 Vlans 1,100-500,1001-1005 will not be pruned on this device. VTP domain Lab_Network modified. Console> (enable) set vtp pruneeligible 250-255 Vlans 2-99,250-255,501-1000 eligible for pruning on this device. VTP domain Lab_Network modified. Console> (enable) show vtp domain Domain Name Domain Index VTP Version Local Mode Password -------------------------------- ------------ ----------- ----------- ---------- Lab_Network 1 2 server - Vlan-count Max-vlan-storage Config Revision Notifications ---------- ---------------- --------------- ------------- 8 1023 16 disabled Last Updater V2 Mode Pruning PruneEligible on Vlans --------------- -------- -------- ------------------------- 172.20.52.2 disabled enabled 2-99,250-255,501-1000 Console> (enable) show trunk Port Mode Encapsulation Status Native vlan -------- ----------- ------------- ------------ ----------- 1/1 auto isl trunking 523 Port Vlans allowed on trunk -------- --------------------------------------------------------------------- 1/1 1-1005 Port Vlans allowed and active in management domain -------- --------------------------------------------------------------------- 1/1 1,522-524 Port Vlans in spanning tree forwarding state and not pruned -------- --------------------------------------------------------------------- 1/1 1,522-524 Console> (enable)
To disable VTP pruning, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Disable VTP pruning in the management domain. | set vtp pruning disable |
Step 2 Verify that VTP pruning is disabled. | show vtp domain |
This example shows how to disable VTP pruning in the management domain:
Console> (enable) set vtp pruning disable This command will disable the pruning function in the entire management domain. Do you want to continue (y/n) [n]? y VTP domain Lab_Network modified Console> (enable)
To monitor VTP activity, including VTP advertisements sent and received and VTP errors, perform this task:
| Task | Command |
|---|---|
Display VTP statistics for the switch. | show vtp statistics |
This example shows how to display VTP statistics on the switch:
Console> (enable) show vtp statistics
VTP statistics:
summary advts received 4690
subset advts received 7
request advts received 0
summary advts transmitted 4397
subset advts transmitted 8
request advts transmitted 0
No of config revision errors 0
No of config digest errors 0
VTP pruning statistics:
Trunk Join Trasmitted Join Received Summary advts received from
non-pruning-capable device
-------- --------------- ------------- ---------------------------
1/1 0 0 0
1/2 0 0 0
Console> (enable)
These sections describe how to use GVRP on Catalyst 6000 and 6500 series switches:
GVRP provides 802.1Q-compliant VLAN pruning and dynamic VLAN creation on 802.1Q trunk ports. With GVRP, the switch can exchange VLAN configuration information with other GVRP switches, prune unnecessary broadcast and unknown unicast traffic, and dynamically create and manage VLANs on switches connected through 802.1Q trunk ports.
GVRP requires supervisor engine software release 5.2 or later.
Table 8-2 shows the default GVRP configuration.
| Feature | Default Value |
|---|---|
GVRP global enable state | Disabled |
GVRP per-trunk enable state | Disabled on all ports |
GVRP dynamic creation of VLANs | Disabled |
GVRP registration mode | normal, with VLAN 1 set to fixed, for all ports |
GVRP applicant state | normal (ports do not declare VLANs when in the STP1 blocking state) |
GARP timers |
|
| 1STP = Spanning-Tree Protocol |
Follow these guidelines when configuring GVRP:
These sections describe how to configure GVRP:
You must enable GVRP globally before any GVRP processing occurs on the switch. Enabling GVRP globally enables GVRP to perform VLAN pruning on IEEE 802.1Q trunk links. Pruning occurs only on GVRP-enabled trunks. For information on setting the per-trunk port GVRP enable state, see the "Enabling GVRP on Individual 802.1Q Trunk Ports" section.
To enable dynamic VLAN creation, you must explicitly enable dynamic VLAN creation globally on the switch as well. For information on enabling dynamic VLAN creation, see the "Enabling GVRP Dynamic VLAN Creation" section.
To enable GVRP globally on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Enable GVRP on the switch. | set gvrp enable |
Step 2 Verify the configuration. | show gvrp configuration |
This example shows how to enable GVRP and verify the configuration:
Console> (enable) set gvrp enable GVRP enabled Console> (enable) show gvrp configuration Global GVRP Configuration: GVRP Feature is currently enabled on the switch. GVRP dynamic VLAN creation is disabled. GVRP Timers(milliseconds) Join = 200 Leave = 600 LeaveAll = 10000 Port based GVRP Configuration: GVRP-Status Registration Port(s) ----------- ------------ -------------------------------------- Enabled Normal 2/1-2,3/1-8,7/1-24,8/1-24 GVRP Participants running on 3/7-8. Console>
There are two per-port GVRP states:
You can configure the static GVRP port-state on any 802.1Q-capable switch ports, regardless of the global GVRP enable state or whether the port is an 802.1Q trunk. However, in order for the port to become an active GVRP participant, you must enable GVRP globally and the port must be an 802.1Q trunk port (either through CLI configuration or DTP negotiation).
To enable GVRP on individual 802.1Q-capable ports, perform this task in privileged mode:
| Task | Command |
|---|---|
Enable GVRP on an individual 802.1Q-capable port. | set port gvrp mod_num/port_num enable |
This example shows how to enable GVRP on 802.1Q-capable port 1/1:
Console> (enable) set port 1/1 gvrp enable GVRP enabled on 1/1. Console> (enable)
To disable GVRP on individual 802.1Q trunk ports, perform this task in privileged mode:
| Task | Command |
|---|---|
Disable GVRP on an individual 802.1Q trunk port. | set port gvrp mod_num/port_num disable |
This example shows how to disable GVRP on 802.1Q trunk port 1/1:
Console> (enable) set port gvrp 1/1 disable GVRP disabled on 1/1. Console> (enable)
You can enable GVRP dynamic VLAN creation only if these conditions are met:
If you enable GVRP dynamic VLAN creation, these configuration restrictions are imposed:
If any port on the switch becomes an ISL trunk (either by CLI configuration or negotiated using Dynamic Trunk Protocol [DTP]) while dynamic VLAN creation is enabled, dynamic VLAN creation is automatically disabled until the conditions for enabling dynamic VLAN creation are restored.
To enable GVRP dynamic VLAN creation on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Enable dynamic VLAN creation on the switch. | set gvrp dynamic-vlan-creation enable |
This example shows how to enable dynamic VLAN creation on the switch:
Console> (enable) set gvrp dynamic-vlan-creation enable Dynamic VLAN creation enabled. Console> (enable)
These sections describe how to configure GVRP registration modes on switch ports:
Configuring an IEEE 802.1Q trunk port in normal registration mode allows dynamic creation (if dynamic VLAN creation is enabled), registration, and deregistration of VLANs on the trunk port. Normal mode is the default.
To configure GVRP normal registration on an 802.1Q trunk port, perform this task in privileged mode:
| Task | Command |
|---|---|
Configure normal registration on an 802.1Q trunk port. | set gvrp registration normal mod_num/port_num |
This example shows how to configure normal registration on an 802.1Q trunk port:
Console> (enable) set gvrp registration normal 1/1 Registrar Administrative Control set to normal on port 1/1. Console> (enable)
Configuring an IEEE 802.1Q trunk port in fixed registration mode allows manual creation and registration of VLANs, prevents VLAN deregistration, and registers all known VLANs on other ports on the trunk port.
To configure GVRP fixed registration on an 802.1Q trunk port, perform this task in privileged mode:
| Task | Command |
|---|---|
Configure fixed registration on an 802.1Q trunk port. | set gvrp registration fixed mod_num/port_num |
This example shows how to configure fixed registration on an 802.1Q trunk port:
Console> (enable) set gvrp registration fixed 1/1 Registrar Administrative Control set to fixed on port 1/1. Console> (enable)
Configuring an IEEE 802.1Q trunk port in forbidden registration mode deregisters all VLANs (except VLAN 1) and prevents any further VLAN creation or registration on the trunk port.
To configure GVRP forbidden registration on an 802.1Q trunk port, perform this task in privileged mode:
| Task | Command |
|---|---|
Configure forbidden registration on an 802.1Q trunk port. | set gvrp registration forbidden mod_num/port_num |
This example shows how to configure forbidden registration on an 802.1Q trunk port:
Console> (enable) set gvrp registration forbidden 1/1 Registrar Administrative Control set to forbidden on port 1/1. Console> (enable)
To prevent undesirable Spanning-Tree Protocol (STP) topology reconfiguration on a port connected to a device that does not support per-VLAN STP, configure the GVRP active applicant state on the port. Ports in the GVRP active applicant state send GVRP VLAN declarations when they are in the STP blocking state, which prevents the STP bridge protocol data units (BPDUs) from being pruned from the other port.
To configure an 802.1Q trunk port to send VLAN declarations when in the blocking state, perform this task in privileged mode:
| Task | Command |
|---|---|
Configure an 802.1Q trunk port to send VLAN declarations when in the blocking state. | set gvrp applicant state {normal | active} mod_num/port_num |
This example shows how to configure a group of 802.1Q trunk ports to send VLAN declarations when in the blocking state:
Console> (enable) set gvrp applicant active 4/2-3,4/9-10,4/12-24 Applicant was set to active on port(s) 4/2-3,4/9-10,4/12-24. Console> (enable)
Use the normal keyword to return to the default state (active mode disabled).
You can modify the default GARP timer values on the switch.
When setting the timer values, the value for leave must be greater than three times the join value (leave 
join * 3). The value for leaveall must be greater than the value for leave (leaveall > leave).
If you attempt to set a timer value that does not adhere to these rules, an error is returned. For example, if you set the leave timer to 600 ms and you attempt to configure the join timer to 350 ms, an error is returned. Set the leave timer to at least 1050 ms and then set the join timer to 350 ms.
 | Caution Set the same GARP timer values on all Layer 2-connected devices. If the GARP timers are set differently on Layer 2-connected devices, GARP applications (for example, GMRP and GVRP) do not operate successfully. |
To adjust the GARP timer values, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Set the GARP timer values. | set garp timer {join | leave | leaveall} timer_value |
Step 2 Verify the configuration. | show garp timer |
This example shows how to set GARP timers and verify the configuration:
Console> (enable) set garp timer leaveall 10000 GMRP/GARP leaveAll timer value is set to 10000 milliseconds. Console> (enable) set garp timer leave 600 GMRP/GARP leave timer value is set to 600 milliseconds. Console> (enable) set garp timer join 200 GMRP/GARP join timer value is set to 200 milliseconds. Console> (enable) show garp timer Timer Timer Value (milliseconds) -------- -------------------------- Join 200 Leave 600 LeaveAll 10000 Console> (enable)
To display GVRP statistics on the switch, perform this task:
| Task | Command |
Display GVRP statistics. | show gvrp statistics [mod_num/port_num] |
This example shows how to display GVRP statistics for port 1/1:
Console> (enable) show gvrp statistics 1/1 Join Empty Received: 0 Join In Received: 0 Empty Received: 0 LeaveIn Received: 0 Leave Empty Received: 0 Leave All Received: 40 Join Empty Transmitted: 156 Join In Transmitted: 0 Empty Transmitted: 0 Leave In Transmitted: 0 Leave Empty Transmitted: 0 Leave All Transmitted: 41 VTP Message Received: 0 Console> (enable)
To clear all GVRP statistics on the switch, perform this task in privileged mode:
| Task | Command |
Clear GVRP statistics. | clear gvrp statistics {mod_num/port_num | all} |
This example shows how to clear all GVRP statistics on the switch:
Console> (enable) clear gvrp statistics all GVRP Statistics cleared for all ports. Console> (enable)
To disable GVRP globally on the switch, perform this task in privileged mode:
| Task | Command |
|---|---|
Disable GVRP on the switch. | set gvrp disable |
This example shows how to disable GVRP globally on the switch:
Console> (enable) set gvrp disable GVRP disabled Console> (enable)
These sections describe how to use VLANs on the Catalyst 6000 and 6500 series switches:
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 located physically on the same LAN segment.
The following sections describe how VLANs work on the Catalyst 6000 and 6500 series switches:
VLANs allow you to group ports to limit unicast, multicast, and broadcast traffic flooding. Flooded traffic originating from a particular VLAN is only flooded out other ports belonging to that VLAN.
Figure 8-3 shows an example of VLANs segmented into logically defined networks.
You can set these parameters when you create a VLAN in the management domain:
VTP version 2 supports two Token Ring VLAN types:
Token Ring Bridge Relay Function (TrBRF) VLANs interconnect multiple Token Ring Concentrator Relay Function (TrCRF) VLANs in a switched Token Ring network (see Figure 8-4). The TrBRF can be extended across a network of switches interconnected through trunk links. The connection between the TrCRF and the TrBRF is referred to as a logical port.
For source routing, the switch appears as a single bridge between the logical rings. The TrBRF can function as a source-route bridge (SRB) or source-route transparent (SRT) bridge running either the IBM or IEEE STP. If SRB is used, you can define duplicate Media Access Control (MAC) addresses on different logical rings.
The Token Ring software runs an instance of STP for each TrBRF VLAN and each TrCRF VLAN. For TrCRF VLANs, STP removes loops in the logical ring. For TrBRF VLANs, STP interacts with external bridges to remove loops from the bridge topology, similar to STP operation on Ethernet VLANs.
| Caution Certain parent TrBRF STP and TrCRF bridge mode configurations can place the logical ports (the connection between the TrBRF and the TrCRF) of the TrBRF in a blocked state. For more information, refer to the "VLAN Configuration Guidelines" section. |
For source routing, the switch appears as a single bridge between the logical rings. The TrBRF can function as an SRB or SRT bridge running either the IBM or IEEE STP. If SRB is used, duplicate MAC addresses can be defined on different logical rings.
To accommodate IBM System Network Architecture (SNA) traffic, you can use a combination of SRT and SRB modes. In a mixed mode, the TrBRF considers some ports (logical ports connected to TrCRFs) to operate in SRB mode while others operate in SRT mode.
Token Ring Concentrator Relay Function (TrCRF) VLANs define port groups with the same logical ring number. You can configure two types of TrCRFs in your network: undistributed and backup.
Typically, TrCRFs are undistributed, which means each TrCRF is limited to the ports on a single switch. Multiple undistributed TrCRFs on the same or separate switches can be associated with a single parent TrBRF (see Figure 8-5). The parent TrBRF acts as a multiport bridge, forwarding traffic between the undistributed TrCRFs.
Within a TrCRF, source-route switching forwards frames based on either MAC addresses or route descriptors. The entire VLAN can operate as a single ring, with frames switched between ports within a single TrCRF.
You can specify the maximum hop count for All-Routes and Spanning-Tree Explorer frames for each TrCRF. This limits the maximum number of hops an explorer is allowed to traverse. If a port determines that the explorer frame it is receiving has traversed more than the number of hops specified, it does not forward the frame. The TrCRF determines the number of hops an explorer has traversed based on the number of bridge hops in the route information field.
A backup TrCRF enables you to configure an alternate route for traffic between undistributed TrCRFs located on separate switches that are connected by a TrBRF, in the event that the ISL connection between the switches fails. Only one backup TrCRF for a TrBRF is allowed, and only one port per switch can belong to a backup TrCRF.
If the ISL connection between the switches fails, the port in the backup TrCRF on each affected switch automatically becomes active, rerouting traffic between the undistributed TrCRFs through the backup TrCRF. When the ISL connection is reestablished, all but one port in the backup TrCRF is disabled. Figure 8-7 illustrates the backup TrCRF.
Table 8-3 shows the default VLAN configuration.
| Feature | Default Value |
|---|---|
Native (default) VLAN | VLAN 1 |
Port VLAN assignments | All ports assigned to VLAN 1 Token Ring ports assigned to VLAN 1003 (trcrf-default) |
VLAN state | Enabled |
MTU size | 1500 bytes 4472 bytes for Token Ring VLANs |
SAID value | 100,000 plus the VLAN number (for example, the SAID for VLAN 3 is 100003) |
Pruning eligibility | VLAN 2-1000 are pruning-eligible |
Default FDDI VLAN | VLAN 1002 |
Default FDDI NET VLAN | VLAN 1004 |
Default Token Ring TrBRF VLAN | VLAN 1005 (trbrf-default) with bridge number 0F |
Default Token Ring TrCRF VLAN | VLAN 1003 (trcrf-default) |
TrBRF STP | IBM |
TrCRF bridge mode | SRB |
Follow these guidelines when creating and modifying VLANs in your network:
These sections describe how to configure VLANs on the Catalyst 6000 and 6500 series switches:
To create a new Ethernet VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Create a new Ethernet VLAN. | set vlan vlan_num [name name] [said said] [mtu mtu] [translation vlan_num] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
If adding a new VLAN, the VLAN number must be within the range 2 to 1001. When modifying a VLAN, the valid range for the VLAN number is 2 to 1005.
This example shows how to create an Ethernet VLAN and verify the configuration:
Console> (enable) set vlan 500 name Engineering Vlan 500 configuration successful Console> (enable) show vlan 500 VLAN Name Status IfIndex Mod/Ports, Vlans ---- -------------------------------- --------- ------- ------------------------ 500 Engineering active 344 VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------ 500 enet 100500 1500 - - - - - 0 0 VLAN AREHops STEHops Backup CRF ---- ------- ------- ---------- Console> (enable)
To modify the VLAN parameters on an existing Ethernet VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Modify an existing Ethernet VLAN. | set vlan vlan_num [name name] [state {active | suspend}] [said said] [mtu mtu] [translation vlan_num] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
To create a new FDDI VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Create a new FDDI or FDDI NET VLAN. | set vlan vlan_num [name name] type {fddi | fddinet} [said said] [mtu mtu] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
To modify the VLAN parameters on an existing FDDI VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Modify an existing FDDI or FDDI NET VLAN. | set vlan vlan_num [name name] [state {active | suspend}] [said said] [mtu mtu] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
To create a new Token Ring TrBRF VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Create a new Token Ring TrBRF VLAN. | set vlan vlan_num [name name] type trbrf [said said] [mtu mtu] bridge bridge_number [stp {ieee | ibm}] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
This example shows how to create a new Token Ring TrBRF VLAN and verify the configuration:
Console> (enable) set vlan 999 name TrBRF_999 type trbrf bridge a Vlan 999 configuration successful Console> (enable) show vlan 999 VLAN Name Status IfIndex Mod/Ports, Vlans ---- -------------------------------- --------- ------- ------------------------ 999 TrBRF_999 active VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------ 999 trbrf 100999 4472 - - 0xa ibm - 0 0 VLAN AREHops STEHops Backup CRF ---- ------- ------- ---------- Console> (enable)
To modify the VLAN parameters on an existing Token Ring TrBRF VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Modify an existing Token Ring TrBRF VLAN. | set vlan vlan_num [name name] [state {active | suspend}] [said said] [mtu mtu] [bridge bridge_number] [stp {ieee | ibm}] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
To create a new Token Ring TrCRF VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Create a new1 Token Ring TrCRF VLAN. | set vlan vlan_num [name name] type trcrf [said said] [mtu mtu] {ring hex_ring_number | decring decimal_ring_number} parent vlan_num |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
| 1You must specify a ring number (either in hexadecimal or in decimal) and a parent TrBRF VLAN when creating a new TrCRF. |
This example shows how to create a Token Ring TrCRF VLAN and verify the configuration:
Console> (enable) set vlan 998 name TrCRF_998 type trcrf decring 10 parent 999 Vlan 998 configuration successful Console> (enable) show vlan 998 VLAN Name Status IfIndex Mod/Ports, Vlans ---- -------------------------------- --------- ------- ------------------------ 998 TrCRF_998 active 352 VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------ 998 trcrf 100998 4472 999 0xa - - srb 0 0 VLAN AREHops STEHops Backup CRF ---- ------- ------- ---------- 998 7 7 off Console> (enable)
To modify the VLAN parameters on an existing Token Ring TrCRF VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Modify an existing Token Ring TrCRF VLAN. | set vlan vlan_num [name name] [state {active | suspend}] [said said] [mtu mtu] [ring hex_ring_num] [decring decimal_ring_num] [bridge bridge_num] [parent vlan_num] |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
To configure a TrCRF VLAN as a backup TrCRF, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Configure a TrCRF VLAN as a backup TrCRF. | set vlan vlan_num backupcrf on |
Step 2 Verify the VLAN configuration. | show vlan [vlan_num] |
| Caution If the backup TrCRF port is attached to a Token Ring multistation access unit (MSAU), it does not provide a backup path unless the ring speed and port mode are set by another device. We recommend that you configure the ring speed and port mode for the backup TrCRF. |
| Task | Command |
|---|---|
Step 1 Specify the maximum number of hops for All-Routes Explorer frames in the TrCRF. | set vlan vlan_num aremaxhop hopcount |
Step 2 Specify the maximum number of hops for Spanning-Tree Explorer frames in the TrCRF. | set vlan vlan_num stemaxhop hopcount |
Step 3 Verify the VLAN configuration. | show vlan [vlan_num] |
This example shows how to limit All-Routes Explorer frames and Spanning-Tree Explorer frames to ten hops, and how to verify the configuration (shown by the arrow):
Console> (enable) set vlan 998 aremaxhop 10 stemaxhop 10 Vlan 998 configuration successful Console> (enable) show vlan 998 VLAN Name Status IfIndex Mod/Ports, Vlans ---- -------------------------------- --------- ------- ------------------------ 998 VLAN0998 active 357 VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2 ---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------ 998 trcrf 100998 4472 999 0xff - - srb 0 0 VLAN AREHops STEHops Backup CRF ---- ------- ------- ----------
998 10 10 off Console> (enable)
A VLAN created in a management domain remains unused until you assign one or more switch ports to the VLAN. If you specify a VLAN that does not exist, the VLAN is created and the specified ports are assigned to it.
To assign one or more switch ports to a VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Step 1 Assign one or more switch ports to a VLAN. | set vlan vlan_num mod_num/port_num |
Step 2 Verify the port VLAN membership. | show vlan [vlan_num] |
This example shows how to assign switch ports to a VLAN and verify the assignment:
Console> (enable) set vlan 560 4/10
VLAN 560 modified.
VLAN 1 modified.
VLAN Mod/Ports
---- -----------------------
560 4/10
Console> (enable) show vlan 560
VLAN Name Status IfIndex Mod/Ports, Vlans
---- -------------------------------- --------- ------- ------------------------
560 Engineering active 348 4/10
VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------
560 enet 100560 1500 - - - - - 0 0
VLAN AREHops STEHops Backup CRF
---- ------- ------- ----------
Console> (enable) show port 4/10
Port Name Status Vlan Level Duplex Speed Type
----- ------------------ ---------- ---------- ------ ------ ----- ------------
4/10 notconnect 560 normal half 10 10BaseT
<...output truncated...>
Last-Time-Cleared
--------------------------
Wed Jun 24 1998, 12:16:41
Console> (enable)
IEEE 802.1Q VLAN trunks support VLANs 1 through 4095. ISL VLAN trunks support VLANs 1 through 1024 (1005 to 1024 are reserved). The switch automatically maps 802.1Q VLANs 1000 and lower to ISL VLANs with the same number.
Use this feature to map 802.1Q VLANs above 1000 to ISL VLANs.
To map an 802.1Q VLAN to an ISL VLAN, perform this task in privileged mode:
| Task | Command |
|---|---|
Map an 802.1Q VLAN to an ISL VLAN. | set vlan mapping dot1q 1q_vlan_num isl isl_vlan_num |
This example shows how to map 802.1Q VLAN 4000 to ISL VLAN 900:
Console> (enable) set vlan mapping dot1q 4000 isl 900 Vlan mapping successful Console> (enable)
When you delete a VLAN in VTP server mode, the VLAN is removed from all switches in the VTP domain. When you delete a VLAN in VTP transparent mode, the VLAN is deleted only on the current switch.
| 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 in privileged mode:
| Task | Command |
|---|---|
Delete a VLAN. | clear vlan vlan_num |
This example shows how to delete a VLAN (in this case, the switch is a VTP server):
Console> (enable) clear vlan 500 This command will deactivate all ports on vlan 500 in the entire management domain Do you want to continue (y/n) [n]?y Vlan 500 deleted Console> (enable)
Posted: Thu Apr 8 14:25:49 PDT 1999
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