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Forwarding RSTP

Phil.Storey
Occasional Contributor

Forwarding RSTP

I have 3 2524 units stacked, the middle switch has both ports 24 & 25 with the stack modules in, the switch above has one stack module and one fibre module in, the switch below has one stack module and one fibre module also.

when I look at the port via cli on either the top switch or the bottom switch with the fiber modules in they both show forwarding,

is this possible ?

in total there are 12 2524 switches of which 3 are stacked.
6 REPLIES
Gerhard Roets
Esteemed Contributor

Re: Forwarding RSTP

Hi Phil

One quick question is this the only 3 switches in the whole topology ?

Can you post the output for the following commands.

show lldp info remote
show span

Awaiting your response
Gerhard
Gerhard Roets
Esteemed Contributor

Re: Forwarding RSTP

Hi Phil

I just noticed your last line.

With RSTP what you are seeing is possible. The key item is the topology should be loop free.

The best solution is
1. Draw the topology and add port mappings
2. use "show span" to identify root bridge
3. Go through all the switch 1 by one and identify blocking ports.

In the end the whole network should be loop free and you should be able to see it.

The blocking links can be on any kind of link(even the stacking link).

HTH
Gerhard
Phil.Storey
Occasional Contributor

Re: Forwarding RSTP

Hello Gerhard
and thankyou for the response.

I tried to use the sh lldp but the switch did not like it or recognise it.

But anyway I did as you suggested and looked at all the switches in the newtork.

I found that the 1st switch after the stack was blocking, and the 6th switch after the stack reported itself as Root.

so I changes the Spanning tree priority on the switch reporting as Root to 15, I then set the priority on the stack commander to "0" now the switch which is about mid point in the network is blocking.

I have another question to do with the stacking modules.

If you have 3 switches in a stack with 2 modules in one switch and one module in each of the other 2 and the commander fails with the two stack modules in then the comms between the two other switches is lost ?

I have been looking at the FW on the switches and it would seem that 5.17 has a bug in it relating to RSTP, I think I should upgrade to the latest stable version, is this 5.72 ?
regards

Gerhard Roets
Esteemed Contributor

Re: Forwarding RSTP

Hi Phil

I would strongly suggest 5.72.

Regarding the following
If you have 3 switches in a stack with 2 modules in one switch and one module in each of the other 2 and the commander fails with the two stack modules in then the comms between the two other switches is lost ?

The stacking links are basically just fast network links.

The commander in the 2524 sense is a central point of control. You will have to look at your topology to see what will happen to the topology.

I would strongly suggest you have a look at
http://ftp.hp.com/pub/networking/software/2500-MgmtConfig-Oct2005-59692354.pdf

Especially have a good read through the bit about spanning tree(in chapter 9) as the explanation is quite good.

It also explains stacking.

I realise this is a bit of reading but it should answer a lot of the posts I have seen ;).

HTH
Gerhard
Phil.Storey
Occasional Contributor

Re: Forwarding RSTP

Hello
sorry for the dely in getting back to you.

I have now looked at the switches 1 by 1. I have now set the middle switch in the stack of 3 as the root switch, now when I look at the switch that is midpoint in the network the is now blocking,

SN MAC Address System Name Device Type Status
-- ------------- ---------------- ----------- ------------
0 000f20-b4da40 Stack Switch 1 HP 2524 Commander Up
1 000f20-b27300 Stack switch 2 HP 2524 Member Up
2 001c2e-6b3f00 Stack switch 3 HP 2524 Member Up

The Root switch is forwarding on both ports
25 1000Stk 20000 128 Forwarding | 000f20-b4da40
26 1000Stk 20000 128 Forwarding | 000f20-b4da40
switch 2 is also forwarding on both ports 25/25 as is switch 2.

I have also put a CAT5e link between switch 2 and 3 should switch 1 fail.this shows one port blocking and one forwarding on switches 2/3.

As I have set the commander to be the root priority of (0) Zero should I set switch 2 with a root priority of 1 and then switch 3 at 2, and leave the rest at default ?

or should I set the one switch that is midpoint ( blocking / forwarding ) to root lower that the rest but higher than switch 1 /2/ 3 /
Many thanks for you help so far

Phil

Phil.Storey
Occasional Contributor

Re: Forwarding RSTP

Could anyone tell me if the 2524 will route between Vlans ?

I have seen some info that states the 2524 is L2 not L3 switch. I need to setup 2 vlans to keep some devices in their own broadcast domain, but two of the devices need to send and receive data from the other vlan.

Also is it possible to put ports into fast mode ?
Regards