Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to

http://www.cisco.com/go/cfn

. An account on Cisco.com is not

required.

Prerequisites for VLAN Trunks

The IEEE 802.1Q trunks impose these limitations on the trunking strategy for a network:

• In a network of Cisco switches connected through IEEE 802.1Q trunks, the switches maintain one

spanning-tree instance for each VLAN allowed on the trunks. Non-Cisco devices might support one
spanning-tree instance for all VLANs.

When you connect a Cisco switch to a non-Cisco device through an IEEE 802.1Q trunk, the Cisco switch
combines the spanning-tree instance of the VLAN of the trunk with the spanning-tree instance of the
non-Cisco IEEE 802.1Q switch. However, spanning-tree information for each VLAN is maintained by

Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1

OL-29440-01