Does HP IRF work the way I think it does?

Question

I finally have approval to better centralize our Ethernet. When last I left off I was looking to the future to figure out how best to handle expansion. Now, I have answers. I now have a pair of A5820 L3 switches that I intend to use as my core. These devices also support HP's new Intelligent Resilient Network (IRF) which seems to be an extra-fancy way of stacking groups of switches.

This looks like it could solve some of my problems. This what I'd like to get to:

The same five 2910al's I had before, but now they have a pair of swanky L3 switches to talk to. Ideally I'd like to wire it as shown: two 10GbE uplinks per switch, one to each core router-like-device. That way I can do maintenance on the routers and not have to deal with a major network outage. Also, link redundancy.

1. What config do my 2910al's need to support this architecture?
   • One trunk-group with two ports, or two independent trunks?
   • Something else entirely?
2. What config do the A5820's need to support this, if any?
3. Or is this such a dog I should stick with standards like VRRP and not bother?

IRF means that the A5820's will be a logical unit, but I don't know if ports on separate switches can be joined into a single trunk-group, or even if that's a good idea.

Answer 1

To get this to work between Comware switches (the 3Com software on the A5000 series) and the ProCurveOS switches (everything else), a few things need to happen.

On the IRF switch

1. The ports linking to the edge switch need to be in a Link Aggregation group.
   1. Start with unconfigured ports.
   2. Add them to the Link Aggregation group (the BAGG interfaces).
   3. Set the link-type on the Aggregation interface to Trunk.
   4. Add VLANs to the resulting aggregation group.

On the ProCurveOS switch

1. The ports linking to the IRF-joined switches need to be in the same Trunk group (not LACP).
2. Add the Trunk port to VLANs that need to be passed.

IRF does indeed make the switch-pair appear to be a single unitary switch as far as config is concerned. It is very much possible to put ports on different switches in the same BAGG interface. Inter-switch traffic is passed over the IRF connections; it seems the switches prefer to keep traffic transiting the IRF pair on the same device where possible, so if you wire all edge switches to both core switches the IRF link won't carry much traffic.

The switches also support LACP trunks, but that doesn't seem to allow more than one VLAN per trunk which is not what I was looking for.