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spanning tree that is vlan based

cisco steps
Level 1
Level 1

Hi, still new to the cisco world. can anyone please explain spanning tree that is vlan based and provide and example if possible .. Thanks

3 Replies 3

n.nandrekar
Level 4
Level 4

hello!

Vlan based spanning tree is nothign but PVST ( per vlan spanning tree) - cisco proprietary, or

MSTP (multiple spanning tree protocol) - 802.1s

PVST runns a spanning tree protocol instance for each vlan. Thus for each vlan, there is a set of root bridge, designated, root and blocked ports. Each vlan cvan have a different root bridge/ or different blocked link. A link blocked for 1 vlan can be made active for another vlan allowing, utilizing bandwidth optimally.

MSTP is similar to PVST but instead of running 1 spanning tree instance for each vlan, 1 instance is run for a group of vlans. So there can be multiple groups of vlans and for each group there is 1 instance again allowing utilization of links while maintaining redundancy.

The following links will give you more idea :

http://www.cisco.com/warp/public/473/147.html

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_20_se/configuration/guide/swmstp.html

Regards,

Niranjan.

(please rate helpful posts)

Thanks Niranjan.

So if I have one interface going from router to switch I need to creatd subinterfaces for each vlan ? assuming I need to create more then 3 vlans

Thanks

alternatively, you could also configure PVRST,

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/44sg/configuration/guide/spantree.html#wp1064592

if the intention is to create routed VLANs, then yes can terminates ur vlans as sub-ifs.

anotehr way is to create SVI or routed VLANs in switch itself as long is it is supported by IOS and H/W.

HTH

Sam

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