You need to examine priorities. In spanning-tree, there is no concept of secondary or backup root. There is only root. When root disappears, or other switch claims better priority, it will become root.
The command "spanning-tree ... root secondary" simply adjusts priority to be slightly above the current root, but less than default value of 32768. -- Marko Milivojevic - CCIE #18427 Senior Technical Instructor - IPexpert YES! We include 400 hours of REAL rack time with our Blended Learning Solution! Mailto: [email protected] Telephone: +1.810.326.1444 Fax: +1.810.454.0130 Web: http://www.ipexpert.com/ On Tue, Jul 27, 2010 at 09:05, marc abel <[email protected]> wrote: > Does anyone know a command that would show you which bridges are secondary > roots? Or do you just have to examine the priorities on each switch? > > On Tue, Jul 27, 2010 at 10:09 AM, marc abel <[email protected]> wrote: >> >> I'm not entirely sure what you are asking but pvst is per vlan spanning >> tree so each vlan can have a different instance of spanning tree and >> therefor each vlan could have a different root bridge. Any single vlan >> should have only 1 root bridge and possibly a secondary root bridge. >> >> On Tue, Jul 27, 2010 at 9:57 AM, P♥Я♥Ä♥Ð♥Ĭ♥P <[email protected]> wrote: >>> >>> Hi, >>> >>> i have single vlan like as vlan 3 and we are running pvst spanning tree. >>> i saw there is single vlan became root bridge for different swithces ? >>> if yes then please guide and suggest for the same or is this any issue? >>> >>> -- >>> Thanks and Regards >>> Pradip S Patole >>> >>> _______________________________________________ >>> For more information regarding industry leading CCIE Lab training, please >>> visit www.ipexpert.com >>> >> > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
