×

Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

stp bpdus

Unanswered Question
pkhatri Thu, 02/02/2006 - 22:07
User Badges:
  • Purple, 4500 points or more

STP will be run on a per-VLAN basis therefore separate BPDUs will be sent on each VLAN ...


Is that what you were asking ?


Paresh.

Thanks for your response.


Here I am asking about the trunk port.What I thought is that STP bpdus are sent (untagged)in native vlan in a

trunk port.May be someone can correct me if my understanding is wrong.


I am wondering about the STP interoperability with any other vendors whose native vlan is not designed as vlan 1 by default.


Can someone pls give a detailed explanation on this..

Francois Tallet Fri, 02/03/2006 - 10:17
User Badges:
  • Gold, 750 points or more

The BPDUs for vlan 1 are always sent untagged to the IEEE address on 1q links, regardless of the native vlan. This is because when running PVST+, vlan 1 is the CST, the unique STP defined in the IEEE specification.

Cisco also sends BPDUs on each and every vlan to a proprietary address, flooded by third party bridges.

If you are running MST, BPDUs will only be sent untagged to the IEEE address. There will be no proprietary BPDUs (this is a pure IEEE standard implementation).

regards,

Francois

Actions

This Discussion