Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

spanning tree

Hi all, can anyone tell me why we have spanning tree per vlan ? and also i have heard that the most switches you can have daisy chained is 7 due to the timers, what timers are these ?

3 REPLIES
New Member

Re: spanning tree

I don't know why you have spanning tree par vlan.

Regarding your second question I haven't heard a specific number like 7 before for number of daisy chained switches. The reason you can't daisy chain an unlimited number of switches is latency. Every switch hop means some delay for a packet in transfer. If you have too many switches daisy chained the packet will timeout.

New Member

Re: spanning tree

It is not true that the "frames" will "timeout".

The daisy chain limit is to ensure that the Spanning Tree will converge in a loop free topology. All of the recommended timers are based on a maximum network "diameter" of 7.

New Member

Re: spanning tree

Hi,

PVST maintains a spanning tree instance for each VLAN configured in the network. It uses ISL Trunking and allows a VLAN trunk to be forwarding for some VLANs while blocking for other VLANs (not the case for normal STP). Since PVST treats each VLAN as a separate network, it has the ability to load balance traffic (at layer-2) by forwarding some VLANs on one trunk and other Vlans on another trunk without causing a Spanning Tree loop.

Hope this helps.

Craig

164
Views
5
Helpful
3
Replies
CreatePlease login to create content