[j-nsp] ex vstp and cisco pvst

[Mohammad]

Hi All

 

We have a layer 2 ring consists of 7 cisco 3750 ME switches terminated on
two juniper EX4200 switches (EX-Primary) and (EX-Backup); the backhaul from
EX-Primary to our HQ is fiber, while we are using a backup microwave link
from EX-Backup to HQ. we have configured vstp on both EX switches and we
have increased the link costs on the backup EX in order to block the port on
the backup EX so that the traffic goes to primary EX and then through the
fiber link to HQ. we have checked the that ports are blocked from the backup
EX,,and everything is working as it should be.

The problem is once we configure vstp on the EX switches we see the cpu
utilization reached 100% for a short period of time and then every things
goes fine, another thing we've noticed suddenly when there is a topology
change in the network the EX malfunction for a short period of time and then
gets back to normal operation !!!!

We are using pvst on the cisco switches.switch port trunk allowed vlan
11,12,13 , etc. is configured on the cisco trunk port

Vlan 1 is not configured on the juniper switches.vstp vlan all is configured
on the juniper switch

The question is:

Shall we configure vlan1 on the juniper switches and put it as a native vlan
on the trunk port facing the cisco switches and also on the trunk port
connecting the two juniper switches?

Shall we configure rapid pvst on the cisco switches instead of normal pvst?

Any better ideas?

 

Thank you in advance.

Mohammad Salbad