A5120 - Stacking vs IRF

[WessexOne]

Hi,

I was hoping someone on this forum might be able to set me straight on the diffence between 'stacking' and 'IRF' (if, in fact, there is a difference).

I have two A5120-24G EL switches that I'm looking to 'merge' for redundancy (they will be connecting a SAN to ESXi servers). Each switch has a "HP 5500 2-port 10GbE Local Connect Module" at the back and I have a "HP X230 Local Connect 50cm CX4 Cable" to connect the two.

I had thought this was something I'd be able to work out fairly easily. However, even though I've learned a lot over the past day or so trawling though the manuals, I'm still not quite certain if 'IRF' means "two switches become one big switch" and if so, what that means for configuring it.

Any clarify shed on "IRF vs Stacking" would be much appreciated.

Regards,
Ben

[Fredrik Lönnman · Accepted solution]

Its basically different words for same thing, BUT different vendors also have different meaning of "stacking". Earlier HP procurve stacking where only management through a "commander", no single IP virtual device, no cross-stack LACP etc. All of thich IRF is. If you know Cisco's 3750 Stackwise, thats how IRF is. "Two switches becomes one big switch" as you put it.

[WessexOne]

Fredrik, many thanks for the clarification.

On a related note, do I actually need the "HP 5500 2-port 10GbE Local Connect Module" to get IRF working or could I just use the four 1000Base-X ports on the front? Some documentation seemed to indicate that I should use these and some documentation seemed to assume the presence of the module.

[Fredrik Lönnman]

The 5120EI needs the 10GbE modules, any 10GbE module will work but the Local Connect Module is the cheapest to use if the switches are adjacent. 

On the 5120SI on the other hand you can do IRF with the 1GbE ports.

[Hendra18]

Do you mean basiclly switch stack different from irf only just management console??

But how about switching capacity or troughput on switch stack? Was aggregate all switch of stack?

Thanks,