2920 Stacking Query

[GrahamElder]

We recently purchased 2 2920-24G switches and as I have with different models of HP switch previously, I puurchased GBICs to allow me to stack the switches.

I'm at the point of configuring the swicthes, and now I read in the documentation that 2920s are stacked differently to other HP switches and require a dedicated stacking module for each switch. This is an expensive option, especially given that I've already bought the gbics.

The stacking requirement comes from wishing to split a VLAN across the two switches for use with Hyper-V.

Can I use the GBIC at all for this or will I need the stacking modules?

Many thanks,

[EricAtHP · Accepted solution]

To do Multi-chassis link aggregation (MLAG) on two 2920s, you will need two stacking modules, J9733A, and one or two stacking cables, J9734A, J9735A, J9736A. Stacking is not possible with standard 10Gig Ethernet ports.

There are real performance and configuration advantages to this style of stacking. First, the stacking cables have a capacity of more than 20Gbps. So you could get more than 40Gbps between the two switches when using 2 stacking cables. Second, the configuration is very easy. At factory defaults, install the stacking modules, connect the stacking cables, and power on the switches. They will automatically form a stack.

Up to 4 2920s can be stacked leaving the 10Gig interfaces available for uplinks. This means that you only need 10Gig modules for two of the four 2920s to give you redundant uplinks.

I hope this helps,

Eric

[Server-Support]

Thanks for sharing the knowledge here Eric !

I was under the impression that the last 4 ports on the right end of the switch can perform Uplinks to the next switch to make it as a stack.

[EricAtHP]

The 2920 and the 3800 used dedicated hardware stacking modules and cables. The advantage of this is that you get much more bandwidth and easier configuration vs using standard ethernet ports. That said, we have a lot of devices that do support IRF which does use standard ethernet ports. It really comes down to a preference. I see both pros and cons for each method.

[GrahamElder]

That teaches me a lesson to 'read the manual' BEFORE placing the order for all the parts based on experience of previous HP switch models.

I realise I'll somehow have to explain to management that I need to spend hundreds more pounds on stacking modules for my 2920s, but now that I have spent the money and have the GBICs and fibre connector for the 2920 - how can they best be utilised to benefit from the investment?

Graham

[EricAtHP]

Can you use them as uplinks to the core/distribution?