10-14-200504:23 AM - last edited on 03-25-201903:00 PM by ciscomoderator
I've the problem that my CAT6K-Switches with Sup1A are facing a very high CPU-Load caused by BPDU-Traffic of about 400 VLANs. I wanted to migrate to MST but because I will still have PVST+ Switches, and it cannot be garantied that there is only one Root-Bridge for all PVST+-VLANS, this is not my solution.
Now since my Cat6k are running on CatOS 8.4(3) I also have the possibility to run MISTP-PVST-mode. Unfortunately I cannot see anywhere how it exactly works to decide whether this can solve my problem or not.
The network has to be very flexible, thus I have to have these many VLANs!
MISTP (802.1s) is an IEEE standard which allows several VLANs to be mapped to a reduced number of spanning-tree instances. This is possible since most networks do not need more than a few logical topologies. Each instance handles multiple VLANs that have the same Layer 2 topology.
Per VLAN Spanning Tree Plus (PVST+) provides the same functionality as PVST using 802.1Q trunking technology rather than ISL. PVST+ is an enhancement to the 802.1Q specification and is not supported on non-Cisco devices.
To view about the spanning tree instance, use the following command on any of your cat6k switches.The o/p will be as below.From this o/p, i think u may be able to identify its overall functionality.
show spantree mistp-instance active
Spanning tree mode MISTP
Spanning tree type ieee
Spanning tree instance enabled
Designated Root xxxxxx
Designated Root Priority 32769
Designated Root Cost 0
Designated Root Port none
VLANs mapped: 1
Root Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec
Bridge ID MAC ADDR xxxxxxx
Bridge ID Priority 32769
VLANs mapped: 1
Bridge Max Age 20 sec Hello Time 2 sec Forward Delay 15 sec