Hello to All,
Topic: stp interoperability between cisco and ex swithc.
ref: https://www.juniper.net/us/en/local/pdf/implementation-guides/8010002-en.pdf
I already read different forum and juniper documentation about this topic and at the end it is valid that:
1)cisco side -> pvstp
2)ex side -> rstp
The above combination should work just fine (except in changing the path cost calculation cisco´s side )
Based on https://www.juniper.net/us/en/local/pdf/implementation-guides/8010002-en.pdf, what is happening is that:
1) juniper´s side simply ignore the bpdu-pvstp sent by the cisco and consider them like normal multicast traffic.
2) juniper´s side is recognizing as standard bpdu the muticast 01:80:C2:00:00:00 bpdu (vlan 1).
Result:
"(...)Since RSTP only has a single Spanning Tree instance for all VLANs across a trunk and there is no vlan awareness, all traffic will be forwarded or blocked based on the VLAN1 topology."
All good.
I have now the following case:
--------------------------------------------
cisco switch "distribution" layer (pvstp)
MAC xxxx.xxxx.3d80, priority 32768
------------------------------------------
fa-1/0/8
|
|
trunk
|
ge-0/0/47
--------------------------------------------
ex switch "access" layer (rstp)
MAC xxxx.xxxx.8441 , priority 61440
------------------------------------------
Easy:
1)configure vlan 9 on both swicthes
2)I create also the vlan1 on ex side
3)configuration interface on ex-side
set interfaces ge-0/0/47 unit 0 family ethernet-switching port-mode trunk
set interfaces ge-0/0/47 unit 0 family ethernet-switching vlan members 9
set interfaces ge-0/0/47 unit 0 family ethernet-switching native-vlan-id 1
4)configuration interface on cisco sdie
interface FastEthernet1/0/8
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 9
switchport mode trunk
end
Result
1)ex side
Spanning tree interface parameters for instance 0
Interface Port ID Designated Designated Port State Role
port ID bridge ID Cost
ge-0/0/47.0 128:560 128:560 61440.xxxx.xxxx.8441 200000 FWD DESG
2)cisco side
show spanning-tree vlan 9
VLAN0009
Spanning tree enabled protocol ieee
Root ID Priority 32777
Address xxxx.xxxx.3d80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32777 (priority 32768 sys-id-ext 9)
Address xxxx.xxxx.3d80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/8 Desg FWD 19 128.10 P2p
I was expecting to see the cisco as root but as you can see I have basically 2 different root and this is not the wished result.
Any hint here?
Thank you.
Thank you.