RPVST and RSTP

Routing & Switching Spanning Tree
#1

Hello,

I would like to know if i can mix RSTP ( other switch ) with RPVST with mutiple vlan. I seen on the network that i mix with the vlan 1 because the bpdu destination mac is similar to rpvst but with the other vlan i think that create a loop. I tested on a maquette : one Cisco root bridge with vlan 1,2 and 3 and 2 other swicths uses RSTP. when i create a loop between the three switchs . one port on the other switchs is alternate blocking and i don’t see a loop. I tagged all vlan exept the vlan 1 that is native.

What do you think of that?

#2

Hello William

It is possible to have both RSTP and R-PVST+ function together, however it can get a little tricky. With the topology that you’ve described above, it sounds like it’s a good solution.

Keep in mind that RSTP should be mapped to the R-PVST+ VLAN 1 instance so VLAN 1 should be allowed on all the trunks, as you have rightly done so.

Many non-Cisco switch manufacturers provide documentation on how to inter-operate STP versions between Cisco and their switches. The following links show two examples of such documentation:


I hope this has been helpful!

Laz

#3

Hello,

Thanks tout vert much for your answer. It comforts me in my installations.

WT

#4

hi Lazaros,

I attached a screenshot of my show span command and it is weird because the bridge id of my switch that is not the root has a lower mac address in total = 64 to the root bridge’s mac address which totals 79 in hex? Why is it the root seeing that they both have the same priority?

Spanning Tree Question
Spanning Tree Question605×501 19.8 KB

#5

Hello Daniel

The root bridge has a MAC address of 000D.BD97.A772 while the local bridge has a MAC address of 00D0.584E.1856. The MAC of the root bridge is actually lower. Note that it starts with 000D while the MAC of the local switch starts with 00D0 which is higher.

The priority is a value that is manually configured to cause one bridge to become root over another. By default, the priority value is 32769, and as you can see here, this has not been changed. Since the priority is the same, the MAC addresses are used to determine which device will become the root.

I hope this has been helpful!

Laz