native vlan for a 3550XL swtich

Unanswered Question
Nov 17th, 2007
User Badges:

hello

i have the follow dilemma. a 3550XL has a voice vlan 10 , a data vlan 20 and an management vlan 99. assinging the vlan 10 as native wil remove its tagg across the trunk ports. also cisco recomends native vlan not be the same as management vlan . but when i made the vlan 99 the vlan 1 goes in shutdown situation . so what is the best practice about tha native vlan into a voice switch ?


thanks

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 3 (1 ratings)
Loading.
smahbub Thu, 11/22/2007 - 10:40
User Badges:
  • Silver, 250 points or more

IEEE 802.1Q Configuration Considerations

IEEE 802.1Q trunks impose these limitations on a network:


In a network of Cisco switches connected through IEEE 802.1Q trunks, the switches maintain one instance of spanning tree 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 Cisco switches separated by a cloud of non-Cisco IEEE 802.1Q switches. The non-Cisco IEEE 802.1Q cloud separating the Cisco switches is treated as a single trunk link between the switches.


Make sure the native VLAN for an IEEE 802.1Q trunk is the same on both ends of the trunk link. If the native VLAN on one end of the trunk is different from the native VLAN on the other end, spanning-tree loops might result.


Disabling spanning tree on the native VLAN of an IEEE 802.1Q trunk without disabling spanning tree on every VLAN in the network can potentially cause spanning-tree loops. We recommend that you leave spanning tree enabled on the native VLAN of an IEEE 802.1Q trunk or disable spanning tree on every VLAN in the network. Make sure your network is loop-free before disabling spanning tree.


http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_25_sec/configuration/guide/swvlan.html


Actions

This Discussion