topic Re: How to use MSTP (2848) with Foundry Router (BigIron)? in Switches, Hubs, and Modems

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

Stefan Priebe — Thu, 02 Apr 2009 19:26:26 GMT

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

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

Pieter 't Hart — Fri, 03 Apr 2009 09:29:59 GMT

"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)

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

Stefan Priebe — Fri, 03 Apr 2009 09:38:15 GMT

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 :-(

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

Stefan Priebe — Fri, 03 Apr 2009 09:41:11 GMT

But Foundry is speaking about MSTP

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

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

Pieter 't Hart — Fri, 03 Apr 2009 09:59:50 GMT

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.

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

Stefan Priebe — Fri, 03 Apr 2009 11:20:16 GMT

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.

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

Stefan Priebe — Fri, 03 Apr 2009 11:23:59 GMT

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.

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

Pieter 't Hart — Fri, 03 Apr 2009 11:35:49 GMT

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.

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

Stefan Priebe — Fri, 03 Apr 2009 11:43:21 GMT

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... :-(

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

Pieter 't Hart — Fri, 03 Apr 2009 12:14:34 GMT

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.

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

Stefan Priebe — Fri, 03 Apr 2009 12:21:40 GMT

yeah that seems to be right. Now i know that - but in the docs it is also named MSTP - that was my fault - i thought MSTP = MSTP...

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

Stefan Priebe — Mon, 06 Apr 2009 09:28:27 GMT

so you don't have another idea?

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

Pieter 't Hart — Mon, 06 Apr 2009 12:21:39 GMT

sorry, what do you want to hear?

MSTP on foundry apearently is not MSTP on HP, but more compareable to RSTP.

MSTP on HP 2848 procurve is meant to divide the spanning-tree topology over multiple instances, but not each port a single vlan with a separate instance, therfore you reach a limit!
HP procurve 2848 does not support rstp.

you can replace the 2848's with devices that CAN do rstp?

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

Jeff Carrell — Mon, 06 Apr 2009 16:33:36 GMT

>HP procurve 2848 does not support rstp.

from the 28XX relnotes:

"Under standard settings, your MSTP-configured switch interoperates effectively
with both STP (IEEE 802.1D) and RSTP (IEEE 802.1w) spanning-tree devices."

you may need to force spanning tree to RSTP...from the ATG manual:

spanning-tree force-version < stp-compatible | rstp-operation |
mstp-operation >

Sets the spanning-tree compatibility mode.

This command forces the switch to emulate behavior of earlier versions of spanning tree protocol, or return to MSTP behavior.
The command is useful in test or debug applications, and removes the need to reconfigure the switch for temporary changes in spanning-tree operation.

stp-compatible: The switch applies 802.1D STP operation on all ports.

rstp-operation: The switch applies 802.1w operation on all ports except those ports where it detects a system using 802.1D
Spanning Tree.

mstp-operation: The switch applies 802.1s MSTP operation on all ports where compatibility with 802.1D or 802.1w spanning
tree protocols is not required.
Note that even when mstp-operation is selected, if the switch detects an 802.1D BPDU or an 802.1w BPDU on a port, it
communicates with the device linked to that port using STP or RSTP BPDU packets. Also, if errors are encountered as described in the â Note on MSTP Rapid State Transitionsâ on
page 4-18, setting force-version to stp-compatible forces the MSTP switch to communicate out all ports using operations
that are compatible with IEEE 802.1D STP.
----

hth...jeff

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

Pieter 't Hart — Tue, 07 Apr 2009 07:19:30 GMT

Jeff, thanks for the info,
to both, in my post i typed RSTP but meant pvstp.