Re: MSTP in RSTP network

LenniBomba · ‎06-18-2021

Hi,
I have to connect a network of 15 switches, of which 3 are MRV supporting MSTP only.

Other switches are operating on rapidPVST. I cant correctly connect them, right now I'm using this manual

The problem is when I set everything up, the connection fails, I lost access to mrvs till they reboot
For example, let's say rapidpvst is set on other switches with tag 500, what should I configure on MSTP? Because setting it with tag 500 doesn't get me a connection.

enable
configure terminal
interface vlan vif1
ports 10
tag 500
exit
spanning-tree
istance 1 vlan 500
instance 1 priority 4096
enable

This somehow isn't right. I have never been configuring an MSTP and I just cant get it to work

pieterh · ‎06-18-2021

- MSTP uses multiple spanning-tree instances, each instance has its set of vlans and it's spanning-tree topology
- (Rapid) PVST determines spanning-tree per-vlan
you need to run them in sync

you created an instance-1 for vlan 500,
NB! in a Cisco environment, there already exists an instance 0 with all vlan's not assigned to a specific instance, This may also count for the MRV environment ? if you add a vlan to MST-1 it is removed from MST-0)
if so then from that point two MSTP topologies are formed instance-0 (vlan1-499, 501-4096) and instance-1 (vlan-500)

the tag 500 command will mean that packets are sent with a vlan-tag,
this has basically nothing to do with spanning-tree, but with vlan-trunking (multiple vlans over the same physical port)
for this to behave as desired you need to configure the Cisco port as a trunk port end allow the same vlans that need to communicate with the MST instance
- switchport mode trunk
- spanning-tree vlan allowed 500
(if the Cisco is connected to the MRV on a second interface, you may need to remover vlan 500 from that port)
if this behaves as desired you can add mode vlans to the spanning-tree instance-1 and to the Cisco port

LenniBomba · ‎06-18-2021

Thanks a lot! Yeah, that's right, there are 2 instances now

True, commands are 1:1 with Cisco on MRV.

Problem is, the other switches aren't cisco, they are probably Extreme(the one with rapidVSTP), and their ports are configured as tag, which i think is the same as trunk on cisco.

So when I get back to the work, should I configure trunk on the port on mrv, and nothing to do on the Extreme side?
I've tried it work labor, with just 2 extreme and 1x mrv. Configured rapidVSTP on Extreme switches at port 1,2+same commands as higher on MRV at port 1,2. When connecting everything(ruckus1,ruckus2,mrv):
Ruckus1 Port 2-> Ruckus2 port 1->Ruckus2 port 2->MRV port 1-> MRV port 2 to Ruckus1 port 2
Extreme switches died, probably cuz of the broadcast storm, so stp didn't even pick up.
Trying the same with 3x Ruckus everything was fine, so for sure I'm not configuring MRV right.

Thanks a lot for the answer!

Elliot Dierksen · ‎06-18-2021

If you want the other switches to run mst, this is the command.

spanning-tree mode mst

You may also be able to change it at the interface level on the switches that run PVST. On the interface that connects to the MST switches, you could try this (or something close to this).

 spanning-tree mst pre-standard

No warranty on this. It is from a config that is 14+ years old. I haven't had to face that issue in quite some time.

pieterh · ‎06-18-2021

keep in mind: this is a Cisco community, and you are connecting Ruckus, Extreme and MRV?
- I allready mentioned: if you add a vlan to MST-1 it is removed from MST-0
- you need to keep both ends of the link in sync

- using the keyword tag on the port is different than tag on the MST instance
both refer to a vlan, but usage is different

for further advise an image of the network and the designed spanning-tree topology may help.

you beter design a network separating "MST domain" and "PVST domain" that are connected.

not a design using an MST "core" and all PVST access-switches around it.
of course you can make it work, but it will be cumbersome to maintain without interrupting operation

LenniBomba · ‎06-22-2021

I know this is CIsco community, but I thought MRV was something like Cisco node that just died... I think I couldn't find any help on MRV forums because they might not even exist anymore

I've asked for an image of the network, and I'll get it asap, sorry for wasting Your time
Do I need to keep it in MST-0? It will forward all VLANs, right? But how can I point out that I want to forward only VLAN 500 (in this example) traffic?

@pieterh wrote:
- using the keyword tag on the port is different than tag on the MST instance
both refer to a vlan, but usage is different

I will educate myself at this, and get back to You, so I don't make myself look so stupid...

LenniBomba · ‎06-22-2021

Yeah, it sounded great. I've changed it on Extreme by

configure stpd mode mstp

And it's all fine on Extreme, but there is still a problem with MRV.

I don't get this switch at all...
I've even tried to make something as simple as for 12 years old kids exercise
Extreme:

port 1-tagged vlan 10

port 2-untagged VLAN 10
MRV:
same thing
Connect each other by port 1

Connect 2 PC's to ports 2... and they can't even ping each other. MRV is a Cisco switch, and I think there would be needed something like a trunk on port 1, but I can't see an option like this even in manuals, and when I check tagging

show port tag

it says the port is 1 tag with right 802.1q...

pieterh · ‎06-22-2021

>>> and I think there would be needed something like a trunk on port 1 <<<
I agree, most likely this is simply created by adding "tag nnn" commands

port 1-tagged vlan 10,11, 22

some devices need the default vlan "1" on a trunk port, (that is they sent BPDU packets only on vlan-1)
so maybe you also need to add "untagged 1" to the connecting ports (or tagged if you like)

p.s. in your initial post I see the command "ports 10"
this could mean if your command is

ports 2
untag 10
ports 3
untag 10
the result is that only port-3 is uses untagged 10
which could explain the 2 PC's not being able to ping

and the syntax for multiple ports in the same vlan should be
ports 2, 3, 4, 5
untag 20

By the way you do not mention any logging output of the switches.
do you see any link up/down messages or spanning-tree messages ?

LenniBomba · ‎06-23-2021

Thanks a lot for help, I did the child exercise
Got webinar in 6 minutes, after it I'll try something with the mstp, because I got an idea thanks to Your help
The other switches are running RSTP, mrv does support only MSTP. As u can see mrvs are edge switches

LenniBomba · ‎06-23-2021

So in the lab, I've configured extremes to run PVST+, and on MRV just enabled MSTP without adding any VLAN to it, but configuring stp to forward and get the 555 bpdu. Now whenever i disconnect/connect the MRV, other switches notice a change in topology, but they don't do anything (probablu cuz they don't have to), but the problem is on the MRV site, he doesn't get any roots, he doesn't know who is the bridge,

etc