G450 Spanning Tree and Port Redundancy

[glimma]

Hi All,

I've recently had to audit a customers Avaya estate and found some programming discrepancies regarding Spanning Tree and Port Redundancy on their G450's.

The customer has got 15 G450's, 10 at the HQ and the remaining are dotted about the country.

The HQ GW's all have Port Redundancy configured, but some have spanning tree enabled and on some it's disabled. The GW's are all connected to the same stack of CISCO switches.

So my questions are:

1- Port Redundancy does not require Spanning Tree to be enabled on the GWs?
2- With Spanning Tree enabled the GW's could participate in the election process to determine the root bridge?
3- With Spanning Tree enabled the GW's will exchange BPDU frames?
4- In what scenario would you enable Spanning Tree on the G450??

Thanks again..

Glimma

 

[mattKnight]

1- Port Redundancy does not require Spanning Tree to be enabled on the GWs?
Correct....
2- With Spanning Tree enabled the GW's could participate in the election process to determine the root bridge?
Yes. Worse than that, the default priority on the G450 is lower than the default priority of a Cisco switch; so it will force a complete spanning tree reconvergence across the network...
3- With Spanning Tree enabled the GW's will exchange BPDU frames?
Yes.
4- In what scenario would you enable Spanning Tree on the G450??
Um, not sure

Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[glimma]

Thanks Matt.

So would you normally enable Spanning Tree on the GW's??

Glimma

 

[sl1input]

Make sure you enable Port Redundancy first, this way the G450 will only allow 1 port active at once and leave 1 port in standby.
Then I normally disable spanning tree on the gateway.
Plug both ports into the LAN switch, you will see only 1 of the ports LED's light up.
Have a ping running from the G450 CLI to CM.
Now remove the active connection, you should see the other port then activate <1 sec.
You may see 1 drop ping.
This is how I normally configure and not have any issues.

 

[OlegPowerC]

Hello!
I use G450 with Cisco catalyst and Nexus and no problem.
G450 default priopity is 32768.
set lower priority in Your switch.
Also I enable lldp - it is itality for troubleshoot

Bridge ID priority: 32768
Bridge Max Age: 20 Bridge Hello Time: 2
Bridge Forward Delay: 15 Tx Hold Count 3
Spanning Tree Version is rapid spanning tree
Spanning Tree Default Path Costs is according to common spanning tree
Port State Cost Priority
------ ------------- ---------- ------------
10/5 Forwarding 4 128
10/6 Blocking 4 128

 

[jimbojimbo]

As a general rule, I have spanning tree disabled and port redundancy setup. This eliminates a variety of issues as well as provides redundancy. Many of the techs don't have a data background and don't understand spanning tree (until they plug a G450 in and bounce a customer's network). Why have spanning tree enabled if you're not using the G450 to route traffic?

 

[OlegPowerC]

I manage Avaya and Cisco and I use RSTP, because I can configure switch and I good know how RSTP work. But Redundancy link also good and simple method. But if use redundancy, do not forget disable spanning tree.
Have a nice day