Wired Intelligent Edge

Hi

I have network base on comware 5 switches (like hp3600) and Core HPE5940 with comware 7. this network based on rstp.

We recently purchased aruba 2930f switches and have difficulty integrating them with the STP protocol. The 2930f Crowns himself to the root.

The configuration on the Aruba:

spanning-tree enable

spanning-tree mode rapid-pvst

spanning-tree force-version rstp-operation 

The configuration on the 5940:

stp global enable

stp mode rstp

stp instance 0 root primary

Without knowing too much about your setup as a first step  on the Aruba 2930F 

I amuse you dont want the 2930F as the root.

Try increasing the STP priority for the vlan in question in the example below done for vlans 1-3 (version 16.10)

spanning-tree vlan 1-3 priority 15

I also note you are mixing MSTP and RSTP on the Comware device as far as I can see.

This may also be causing your issue please refer to the documentation for your version to clarify  i.e 

1. Comware in STP/RSTP  the command for root is:-  stp root primary

2. Comware in PVST the command for root is:- stp vlan [vlan list] root primary

3. Comware MSTP the command is:- stp instance [instance list] root primary

Id recommend testing  this in a lab/dev/test environment first or seek help from a authorised partner before you go live.

It did not solve the problem
Still the 2930f thinks it is the root

But the 5940 didn't block the uplink although we config STP root-protection

The switch translate the command "stp root primary" to "stp instance 0 root primary"

I double check the config on the comware and it's spanning mode is RSTP (comware does not support RPVST)

Ronelsh

I was checking you have rstp v mstp and yes acknowledged stp  root primary does show in final config as stp instance 0 root primary

Having said that Comware does support rapid pvst on upstream/downstream when Comware is in rstp and neighbour is in rapid-pvst, this being your case.

Here is my working config with the Comware device working as root.

I only have vlan1 running.

------------------------------------------------------------------------------------------

Comware

stp instance 0 root primary
stp mode rstp
stp global enable

ArubaOS

spanning-tree
spanning-tree mode rapid-pvst

----------------------------------------------------------------------------------------------

To check this I have a luxury of a small lab and I could flip the root by manipulating the cost on Comware, as an FYI (do not try this in your live environment)

Comware

undo stp root

stp priorty 61440

This makes the ArubaOS switch root as its default cost is 32678 (8X4096,  8 is default ), the Comware box having 61440.

Id suggest contacting support so they can help you dig deeper.

Hi Ronelsh,

for me it doesn't make sense to use Rapid-PVST Mode on the ArubaOS-Switch devices as this a mode designed for compatibility with Cisco switches. It calculates one spanning tree per vlan. But you want to have a network wide spanning tree together with the comware switches, thus one instance for all switches.

ArubaOS-Switch devices offer two modes: mstp and rapid-pvst. First you should change to mstp mode on the 2930s. In mstp mode, you can select VERSION "stp-compatible" for legacy STP (802.1D-1998), "mstp-operation" for 802.1s MSTP and "rstp-operation" for RSTP (802.1w which is incorporated in 802.1D-2004, the current STP standard).

So the config should look like this:

spanning-tree enable

spanning-tree mode mstp

spanning-tree force-version rstp-operation

I would furthermore recommend to use on all comware switches the following command in addition to the config you already have:

stp pathcost-standard dot1t

This will set the default pathcosts on comware to the 802.1t metric which is also used on Aruba per default. It ensures all switches have a common understanding of the pathcosts.

Hope this helps,

Frank.

Hi fanstoet,

I tested the settings in a lab environment
This seems to solve the problem:

spanning-tree enable

spanning-tree mode mstp

spanning-tree force-version rstp-operation

There's something I still do not understand

The command sh spanning-tree show that the

CST root MAC address: the comware switch

IST Regional Root MAC address: the aruba himself 

What it means?

A Region within MSTP is a group of switches with common configuration. CST is the common spanning tree which interconnects several regions. When you use RSTP this represents a special case in which each switch forms a region of its own and, as there is only one switch in the region, it is the root bridge there.However this is only the mstp perspective which doesn't matter in your case. Important is only the CST root bridge which is the root bridge for your entire L2 domain. If this is the comware switch with prio 0 everything is fine.

Cheers F.

Hi fanstoet,

Thanks so much for the help!