ProCurve 2824 Failover Help

[C Delaney]

Dear All,

I am trying to configure three Procurve 2824s in a failover mesh-like topology but have come unstuck.

Each switch has 3 VLANs set up, one for our SAN (VLAN 2), one for VMWare VMotion traffic (VLAN 3) and the default (VLAN 1). Two of the switches connect to the third using fibre links from each of the SAN and VMotion VLANs. This gives a triangle with no bottom shaped topology.

What I'd like to do is connect the two bottom switches together to provide failover, however, I'd like to keep the traffic physically separate as per the enclosed diagram. This would mean connections between the SAN and VMotion VLANs.

I have tried enabling spanning tree on the switches but this did not work quite as I'd liked - the VMotion network was cut of completely. What do I need to do to give me the failover I want? Any help would be most appreciated.

Chris

[Igoris_1]

enable VLAN tagging on links between switches, make sure VLAN2 and VLAN 3 are configured there as tagged.

[C Delaney]

Do you mean trunk the fibre connections, add VLAN tagging and then enable RSTP?

[Igoris_1]

yes, all ports connecting switches must be members of all VLANs that you need to work in failover scenario. In other words trunk. Then enable RSTP.

[Matt Hobbs]

If you want more control over which links the traffic takes, use MSTP instead.

With 3 VLANs and 3 switches, First tag all VLANs on all switch-to-switch links. (You would do this with RSTP too).

Next create 3 MSTP instances, instance 1 for VLAN 1, instance 2 for VLAN 2, instance 3 for VLAN 3.

Finally, set the instance priorities. For example, switch-1 I would make the root for instance 1, switch-2 root for instance 2 and switch 3 root for instance 3.

This will give you the type of failover you're after, and will also better utilisation of blocked links.

[C Delaney]

OK, so what you're saying is that I can't keep the traffic physically separate on the switch-to-switch links?

I'm afraid that my switch config skills are weak at best - what commands are required to set up MSTP instances and such?

How would you recommend connecting switch 1 and switch 2 - using another 2 gig trunk (HP trunk not Cisco trunk) with the VLAN tagging?

Many thanks.

Chris

[André Beck]

Hi Chris,

> OK, so what you're saying is that I can't
> keep the traffic physically separate on the
> switch-to-switch links?

Of course you could. It's just that in normal situations, you don't have the infrastructure (fibres) to do this, and it will not scale when more VLANs are added. However, doing it for some dedicated VLANs will work. Just make the ports at each end untagged in the relevant VLAN and connect them.

In theory, that's it. In practice, you don't have per-VLAN Spanning Tree on ProCurves, so building such structures can have surprising consequences to your STP topology. So I second the proposal to have this set up with MSTP, even though configuring MSTP is a PITA.

HTH,
Andre.

[C Delaney]

Hmm. OK - so let's say I want to go ahead with the MSTP setup. What is the accepted method for configuring it?

How's this?
- Create (HP) trunks between switch 1 and switch 3 plus between switch 2 and switch 3.
- Add VLAN tagging to the trunks.
- Configure the MSTP instances and such (I could do with some pointers on how do so this please).
- Connect switch 1 and switch 2 with an additional (HP) trunk and add the VLAN tagging.

When I say (HP) trunk I mean more than one connection working together like Cisco etherchannel.