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Table of Contents
Configuring VTP and Virtual LANs
Using VTP
Understanding How VTP Works
Understanding the VTP Domain
Understanding VTP Modes
Understanding VTP Advertisements
Understanding VTP Version 2
Understanding VTP Pruning
VTP Default Configuration
VTP Configuration Guidelines
Configuring VTP
Configuring a VTP Server
Configuring a VTP Client
Disabling VTP
Enabling VTP Version 2
Disabling VTP Version 2
Configuring VTP Pruning
Disabling VTP Pruning
Monitoring VTP
Using VLANs
Understanding How VLANs Work
Understanding VLANs in a VTP Domain
Understanding Token Ring VLANs
VLAN Default Configuration
VLAN Configuration Guidelines
Configuring VLANs
Creating or Modifying an Ethernet VLAN
Creating or Modifying an FDDI VLAN
Creating or Modifying a Token Ring TrBRF VLAN
Creating or Modifying a Token Ring TrCRF VLAN
Assigning Switch Ports to a VLAN
Deleting a VLAN
Configuring VTP and Virtual LANs
This chapter describes how to configure VLAN Trunk Protocol (VTP) and virtual LANs (VLANs).
Note
For complete syntax and usage information for the commands used in this chapter, refer to the
Catalyst
5000 Series Command Reference
publication. This chapter consists of these sections:
·
Using VTP
·
Using VLANs
Using VTP
These sections describe how to use VTP with the Catalyst 5000 series switches:
·
Understanding How VTP Works
·
VTP Default Configuration
·
VTP Configuration Guidelines
·
Configuring VTP
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 Catalyst 5000 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 5000 series switches:
·
Understanding the VTP Domain
·
Understanding VTP Modes
·
Understanding VTP Advertisements
·
Understanding VTP Version 2
·
Understanding VTP Pruning
Understanding the VTP Domain
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 one and 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, the Catalyst 5000 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.
Understanding VTP Modes
You can configure a Catalyst 5000 series switch to operate in any one of these VTP modes:
·
Server--In VTP server mode, you can create, modify, and delete VLANs and specify other configuration
parameters (such as VTP version and VTP pruning) for the entire VTP domain. 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. VTP server is the
default mode.
·
Client--VTP clients behave the same way as VTP servers, but 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. However, in VTP version 2, transparent switches do forward VTP advertisements that
they receive out their trunk ports.
Understanding VTP Advertisements
Each Catalyst 5000 series 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:
·
VLAN IDs (ISL and 802.1Q)
·
Emulated LAN names (for ATM LANE)
·
802.10 SAID values (FDDI)
·
VTP domain name
·
VTP configuration revision number
·
VLAN configuration, including maximum transmission unit (MTU) size for each VLAN
·
Frame format
Understanding VTP Version 2
If you use VTP in your network, you must decide whether to use VTP version
1 or version
2. VTP version 1 is
supported in Catalyst
5000 series supervisor engine software release 2.1 or later and ATM software release 3.1
or later. VTP version
2 is supported in Catalyst
5000 series software release
3.1(1) and later.
Note
If you are using VTP in a Token Ring environment, 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 RAM (NVRAM).
·
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. Since only one domain is supported in the Catalyst
5000 series software, VTP version 2
forwards VTP messages in transparent mode, without checking the version.
·
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 or SNMP. Consistency checks are
not performed when new information is obtained from a VTP message, or when information is read
from NVRAM. If the digest on a received VTP message is correct, its information is accepted without
consistency checks.
Understanding VTP Pruning
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 Catalyst
5000 series software release
2.3 and later.
Figure 13-1
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
13-1: Flooding Traffic without VTP Pruning
Figure 13-2
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).
Figure
13-2: Flooding Traffic with VTP Pruning
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.
VTP Default Configuration
Table 13-1
shows the default VTP configuration.
Table
13-1: 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
VTP Configuration Guidelines
Follow these guidelines when implementing VTP in your network:
·
All switches in a VTP domain must run the same VTP version.
·
You must configure a password on each Catalyst 5000 series switch in the management domain when in
secure mode.
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 Catalyst 5000 series 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 VTP version 2 is disabled on the VTP version 2-capable switch (VTP 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 VTP version
2 on a switch, all of the version
2-capable switches in
the domain enable VTP version
2.
·
In a Token Ring 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.
·
Making VLANs pruning-eligible or pruning-ineligible on a switch affects pruning-eligibility for those
VLANs on that device only (not on all switches in the VTP domain).
Configuring VTP
These sections describe how to configure VTP on the Catalyst 5000 series switches:
·
Configuring a VTP Server
·
Configuring a VTP Client
·
Disabling VTP
·
Enabling VTP Version 2
·
Disabling VTP Version 2
·
Configuring VTP Pruning
·
Disabling VTP Pruning
·
Monitoring VTP
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 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)
Configuring a VTP Client
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)
Disabling VTP
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) 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 will enable version
2 as well.
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 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)
Disabling VTP Version 2
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)
Configuring VTP Pruning
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)
Disabling VTP Pruning
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) s
et 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) Monitoring VTP
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)
Using VLANs
These sections describe how to use VLANs on the Catalyst 5000 series switches:
·
Understanding How VLANs Work
·
VLAN Default Configuration
·
VLAN Configuration Guidelines
·
Configuring VLANs
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
located physically on the same LAN segment.
The following sections describe how VLANs work on the Catalyst 5000 series switches:
·
Understanding VLANs in a VTP Domain
·
Understanding Token Ring VLANs
Understanding VLANs in a VTP Domain
VLANs allow you to group ports on Catalyst 5000 series switches 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.
Note
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 "Using VTP" section
. Figure 13-3
shows an example of VLANs segmented into logically defined networks.
Figure
13-3: VLANs as 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.
Note
Catalyst 5000 series switches support dynamic VLAN membership using the VLAN Membership Policy
Server (VMPS). For information on how to configure VMPS and dynamic port VLAN membership, refer to the
"
Configuring Dynamic Port VLAN Membership with VMPS
" chapter. The in-band (sc0) interface of a Catalyst 5000 series switch can be assigned to any VLAN, so you can access
another Catalyst 5000 series switch on the same VLAN directly without a router. Only one IP address at a time
can be assigned to the in-band interface. If you change the IP address and assign the interface to a different
VLAN, the previous IP address and VLAN assignment are overwritten.
You can set these parameters when you create a VLAN in the management domain:
·
VLAN number
·
VLAN name
·
VLAN type (Ethernet, Fiber Disributed 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
Note
When translating from one VLAN type to another, the Catalyst 5000 series switch requires a different
VLAN number for each media type. Understanding Token Ring VLANs
Two Token Ring VLAN types are supported on Catalyst 5000 series switches running VTP version
2:
·
Token Ring TrBRF VLANs
·
Token Ring TrCRF VLANs
Token Ring TrBRF VLANs
Token Ring Bridge Relay Function (TrBRF) VLANs interconnect multiple Token Ring Concentrator Relay
Function (TrCRF) VLANs in a switched Token Ring network (see Figure 13-4
). The TrBRF can be extended
across a network of switches interconnected via trunk links. The connection between the TrCRF and the TrBRF
is referred to as a logical port. Figure
13-4: Interconnected Token Ring TrBRF and TrCRF VLANs
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 Catalyst 5000 series 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 TrCRF VLANs
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 Catalyst
5000
series switch. Multiple undistributed TrCRFs on the same or separate switches can be associated with a single
parent TrBRF (see Figure 13-5
). The parent TrBRF acts as a multiport bridge, forwarding traffic between the
undistributed TrCRFs.
Note
To pass data between rings located on separate switches, you can associate the rings to the same TrBRF
and configure the TrBRF for SRB. Figure
13-5: Undistributed TrCRFs
Note
By default, Token Ring ports are associated with the default TrCRF (VLAN 1003, trcrf-default), which
has the default TrBRF (VLAN 1005, trbrf-default) as its parent. In this configuration, a distributed TrCRF is
possible (see Figure 13-6
), and traffic is passed between the default TrCRFs located on separate switches
provided that the switches are connected via an ISL trunk. Figure
13-6: Distributed TrCRF
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 13-7
illustrates the backup TrCRF.
Figure
13-7: Backup TrCRF
VLAN Default Configuration
Table 13-2
shows the default VLAN configuration.
Table
13-2: VLAN Default 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 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
VLAN Configuration Guidelines
Follow these guidelines when creating and modifying VLANs in your network:
·
A maximum of 250 VLANs can be active at any time.
·
Before you can create a VLAN, the switch must be in VTP server mode or VTP transparent mode. If the
switch is a VTP server, you must define a VTP domain. For information on configuring VTP, refer to
the "Configuring VTP" section
.
·
The default TrBRF (VLAN 1005) can only be the parent of the default TrCRF (VLAN 1003). You
cannot specify the default TrBRF as the parent of a user-configured TrCRF.
·
You must configure a TrBRF before you configure the TrCRF (the parent TrBRF VLAN you specify
must exist).
·
In a Token Ring environment, the logical ports (the connection between the TrBRF and the TrCRF) of
the TrBRF are placed in a blocked state if either of these conditions exists:
o
The TrBRF is running the IBM STP, and the TrCRF is in SRT mode.
o
The TrBRF is running the IEEE STP, and the TrCRF is in SRB mode.
Configuring VLANs
Note
VLANs support a number of parameters that are not discussed in detail in this section. For complete
information on the set vlan
command and its parameters, refer to the Catalyst
5000 Series Command Reference
publication. These sections describe how to configure VLANs on the Catalyst 5000 series switches:
·
"Creating or Modifying an Ethernet VLAN" section
·
"Creating or Modifying an FDDI VLAN" section
·
"Creating or Modifying a Token Ring TrBRF VLAN" section
·
"Creating or Modifying a Token Ring TrCRF VLAN" section
·
"Assigning Switch Ports to a VLAN" section
·
"Deleting a VLAN" section
Creating or Modifying an Ethernet VLAN
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
]
Note
The default VLAN type is Ethernet; if you do not specify the VLAN type, the VLAN is an Ethernet
VLAN. 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
]
Creating or Modifying an FDDI VLAN
To create a new FDDI VLAN, perform this task in privileged mode: Task Command Step
1 Create a new FDDI or FDDI NET type
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
type VLAN.
set vlan
vlan_num
[
name
name
] [
state
{
active
| suspend
}]
[
said
said
] [
mtu
mtu
]
Step
2 Verify the VLAN configuration.
show vlan
[
vlan_num
]
Creating or Modifying a Token Ring TrBRF VLAN
Note
You must enable VTP version 2 before you create Token Ring VLANs. For information on enabling VTP
version
2, refer to the "Configuring VTP" section
. To create a new Token Ring TrBRF VLAN, perform this task in privileged mode: Task Command Step
1 Create a new Token Ring
TrBRF type 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
]
Note
You must specify a bridge number when creating a new TrBRF. 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 type 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
]
Creating or Modifying a Token Ring TrCRF VLAN
Note
You must enable VTP version 2 before you create Token Ring VLANs. For information on enabling VTP
version
2, refer to the "Configuring VTP" section
. To create a new Token Ring TrCRF VLAN, perform this task in privileged mode: Task Command Step
1 Create a new Token
Ring TrCRF type 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
]
Note
You 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 type
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 create a backup TrCRF, assign one port on each switch that the TrBRF traverses to the backup TrCRF.
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. To specify the maximum number of hops for All-Routes Explorer frames or Spanning-Tree Explorer frames in
the TrCRF, perform this task in privileged mode: 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)
Assigning Switch Ports to a VLAN
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.
Note
Make sure you assign switch ports to a VLAN of the proper type. For example, assign Ethernet, Fast
Ethernet, and Gigabit Ethernet ports to Ethernet-type VLANs, Token Ring ports to Token Ring TrCRF-type
VLANs, and so forth. 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
]
show port
[
mod_num
[
/
port_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)
Deleting a VLAN
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
Note
You cannot delete a Token Ring TrBRF VLAN without first reassigning its child TrCRFs to another
parent TrBRF, or deleting the child TrCRFs. 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: Wed Aug 2 15:47:53 PDT 2000 Copyright 1989-2000
©
Cisco Systems Inc.
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formymemo
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