7-12
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
Chapter 7 Configuring LAN Ports for Layer 2 Switching
Configuring LAN Interfaces for Layer 2 Switching
When configuring the list of VLANs allowed on a trunk, note the following syntax information:
• The vlan parameter is either a single VLAN ID or a range of VLAN IDs described by two
VLAN IDs, the lesser one first, separated by a dash. Do not enter any spaces between
comma-separated vlan parameters or in dash-specified ranges.
• With Release 12.1(13)E and later releases, the VLAN IDs can be 1 to 4094, except for reserved
VLANs (see Table 9-1 on page 9-2).
• With 12.1 E releases earlier than Release 12.1(13)E, the VLAN IDs can be 1 to 1005.
• All VLANs are allowed by default.
• With Release 12.1(13)E and later releases, you can remove the default VLANs (1002–1005) from a
trunk. With earlier releases, you cannot remove any of the default VLANs from a trunk.
• With Release 12.1(11b)E or later, you can remove VLAN 1. If you remove VLAN 1 from a trunk,
the trunk interface continues to send and receive management traffic, for example, Cisco Discovery
Protocol (CDP), VLAN Trunking Protocol (VTP), Port Aggregation Protocol (PAgP), and DTP in
VLAN 1.
Note Complete the steps in the “Completing Trunk Configuration” section on page 7-13 after performing the
tasks in this section.
Configuring the List of Prune-Eligible VLANs
Note Complete the steps in the “Preparing a Layer 2 Switching Port for Configuration as a Trunk” section on
page 7-8 before performing the tasks in this section.
To configure the list of prune-eligible VLANs on the Layer 2 trunk, perform this task:
When configuring the list of prune-eligible VLANs on a trunk, note the following syntax information:
• The vlan parameter is either a single VLAN ID or a range of VLAN IDs described by two
VLAN IDs, the lesser one first, separated by a dash. Do not enter any spaces between
comma-separated vlan parameters or in dash-specified ranges.
• With Release 12.1(13)E and later releases, the VLAN IDs can be 1 to 4094, except for reserved
VLANs (see Table 9-1 on page 9-2).
• With 12.1 E releases earlier than Release 12.1(13)E, the VLAN IDs can be 1 to 1005.
• The default list of VLANs allowed to be pruned contains all VLANs.
• Network devices in VTP transparent mode do not send VTP Join messages. On Cisco 7600 series routers
with trunk connections to network devices in VTP transparent mode, configure the VLANs used by the
transparent-mode network devices or that need to be carried across the transparent-mode network devices
as pruning ineligible.
Command Purpose
Router(config-if)# switchport trunk pruning vlan
{none |{{add | except | remove}
vlan[,vlan[,vlan[,...]]}}
(Optional) Configures the list of prune-eligible VLANs on the
trunk (see the “Understanding VTP Pruning” section on
page 8-3).
Router(config-if)# no switchport trunk pruning vlan
Reverts to the default value (all VLANs prune-eligible).
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