How to use MSTP (2848) with Foundry Router (BigIron)?

[Stefan Priebe]

Hi!

I'm trying to seperate each custom into a serate vlan. While doing this i wanted to split the STP config into an MSTP per VLAN config. But when i try to do this the HP Procurves MSTP implementation doesn't seem to be compatible with Foundry ones...

Any idea how to solve this?

Also i was wondering that i can only create 16 MSTP instances - when i have 48 ports i would like to connect 46 customers and each should have it's own STP instance...

Regards,
Stefan

[Pieter 't Hart]

"mstp" means multiple spanning-tree instances,
The switch has multiple processes (instance) each managing spanning-tree topology for a number of vlan's.

what you seem to look for is "pvst" : per-vlan-spanning-tree.

i don't think the 2848 can do pvst
features : Spanning Tree (STP, RSTP, MSTP)

[Stefan Priebe]

Thanks for your reply. So the only difference between pvst and mstp is that i can have multiple vlans in one mstp instance? But were is the advantage of mstp? i thought it is the same :-(

[Stefan Priebe]

But Foundry is speaking about MSTP

See: http://www.foundrynetworks.co.jp/services/documentation/sribcg/STP.html every time.

[Pieter 't Hart · Accepted solution]

from the "Advanced traffic management guide" :
>>>
MST Regions
All MSTP switches in a given region must be configured with the same VLANs. Also, each MSTP switch within the same region must have the same VLAN-to-instance assignments. (A VLAN can belong to only one instance within any region.) Within a region:
â  
All of the VLANs belonging to a given instance compose a single, active spanning-tree topology for that instance.
â  
Each instance operates independently of other regions.

MST Region: An MST region forms a multiple spanning tree domain and is a
component of a single spanning-tree domain within a network. For switches
internal to the MST region:
â  
All switches have identical MST configuration identifiers (region name and revision number).
â  
All switches have identical VLAN assignments to the regionâ s IST and (optional) MST instances.
â  
One switch functions as the designated bridge (IST root) for the region.
â  
No switch has a point-to-point connection to a bridging device that cannot process RSTP BPDUs.
<<<

So each MSTP instance configuration must match the connected other switches.

I have a question: if you assign each port in it's own vlan what's your worry about spanning-tree?
this switch will never have need to block a port because two ports are connected to the same network (vlan)?
You can disable spanning-tree on this switch and let an external switch do blocking if neccessary.
als long as this switch transparently forwards BPDU's.

[Stefan Priebe]

Mhm you idea seems to be great. I haven't think about it.

I've attached a small picture - how the network looks like.

Each Rack has it's own VLAN up to the Foundry's. So you mean i don't need to setup STP at all on the HP switches? (makes sense cause Foundry 2 would block the link in the VLAN to the HP 2848)

I think this is a really great idea.

[Stefan Priebe]

mhm but there's a problem i haven't thought about. Foundry 2 would block the link to HP 2848 but there will be still a loop between both HP 2848 and the Rack itself.

[Pieter 't Hart]

yes,
in your drawing you've connected the two 2848's.
if you remove this connection then the foundry's can resolve the loop,
with this connection the 2848's itself must also be able to resolve the loop.

you can also change this interconnect to an uplink to the other foundry.

[Stefan Priebe]

mhm but when i remove the interconnect i've the problem that every traffic has to go through foundry 2 if the first switch broke... i like ring structures :-)

It's really crazy for me that every supplier defines MSTP in another way... :-(

[Pieter 't Hart]

http://www.foundrynetworks.co.jp/services/documentation/sribcg/VLANs.html#33752
says:
Since each port-based VLAN is a separate Layer 2 broadcast domain, by default each VLAN runs a separate instance of the Spanning Tree Protocol (STP).

so this is more like pvst than mstp in procurve terms.