Solved: PVST requirement

Manu Shankar · ‎04-07-2010

What is the requirement to run PVST smoothly on a cisco switch. Does this CISCO proprietry ? I mean the IOS version, switch type, links etc..

Regards

Manu

Ganesh Hariharan · ‎04-07-2010

What is the requirement to run PVST smoothly on a cisco switch. Does this CISCO proprietry ? I mean the IOS version, switch type, links etc..

Regards

Manu

Hi Manu,

PVST is per vlan spanning tree this is the original Cisco proprietary, per vlan spanning tree protocol. It maintains a spanning tree instance for each VLAN and it works in all cisco switches by default.

Hope to help !!

Ganesh.H

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Jon Marshall · ‎04-08-2010

manu_nambu wrote:

What is the requirement to run PVST smoothly on a cisco switch. Does this CISCO proprietry ? I mean the IOS version, switch type, links etc..

Regards

Manu

No specific requirements because PVST+ has been around for ages. It is Cisco proprietary but as long as all your switches are Cisco you will be fine.

As for it running smoothly, STP is one of those things that just generally works with a minimum of configuration. If you can and your switches support it i would recommend running Rapid-PVST as it has much quicker failover times and has also integrated some of the addtional features of STP such backbone fast/uplink fast/portfast.

Jon

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Ganesh Hariharan · ‎04-07-2010

What is the requirement to run PVST smoothly on a cisco switch. Does this CISCO proprietry ? I mean the IOS version, switch type, links etc..

Regards

Manu

Hi Manu,

PVST is per vlan spanning tree this is the original Cisco proprietary, per vlan spanning tree protocol. It maintains a spanning tree instance for each VLAN and it works in all cisco switches by default.

Hope to help !!

Ganesh.H

Remember to rate the helpful post

Jon Marshall · ‎04-08-2010

manu_nambu wrote:

What is the requirement to run PVST smoothly on a cisco switch. Does this CISCO proprietry ? I mean the IOS version, switch type, links etc..

Regards

Manu

No specific requirements because PVST+ has been around for ages. It is Cisco proprietary but as long as all your switches are Cisco you will be fine.

As for it running smoothly, STP is one of those things that just generally works with a minimum of configuration. If you can and your switches support it i would recommend running Rapid-PVST as it has much quicker failover times and has also integrated some of the addtional features of STP such backbone fast/uplink fast/portfast.

Jon

Manu Shankar · ‎04-09-2010

Hi Ganesh & Jon,

First of all thanks. I just started reading the BCMSN switching. STP/ RSTP & PVST/RPVST are very interesting, but little bit confusing.

If I have more VLAN in my network,will it affect switches's processing speed or conergence time ?

Do we need to configure this in every single switch ?

Giuseppe Larosa · ‎04-09-2010

Hello Manu,

>> Do we need to configure this in every single switch ?

yes

Spanning-tree mode is configured per switch using

spanning-tree mode ?
mst Multiple spanning tree mode
pvst Per-Vlan spanning tree mode
rapid-pvst Per-Vlan rapid spanning tree mode

>> If I have more VLAN in my network,will it affect switches's processing speed or conergence time ?

PVST and Rapid PVST have some scalability issues, there are some low end switches that support only few STP instances for example 64 on a C2950 with some images.

The use of

switchport trunk allowed vlan x,y,z

on both sides of uplink links of access layer switches help

An STP instance for vlan X is started if at least one port, including trunk ports is up in vlan X.

So allowing only used vlans to an access switch is very important to achieve STP scalability instead of allowing all vlans

The work has to be done on both sides of each uplink.

The best scalability is achieved with MST 802.1s that is able to map a group of vlans to a single STP instance using 802.1W Rapid STP.

with MST the 4094 possible vlan space can be divided in groups and associated to multiple STP instances.

MST 802.1s is standard based but requires some attention and a provisioning phase.

Hope to help

Giuseppe