5900 IRF MAD recommendations

[gtallan]

We have a couple of 5900-48XG-4QSFP irf pairs set up as one pair per building, with direct fiber links between the two buildings (one for each IRF member, as a single LACP link). We're using QSFP direct-attach cables for the IRF links.

My only remaining issue, as a comware newcomer, is configuring MAD. The documentation is fine as far as it goes but is a bit lacking in overall guidelines, as to why you'd choose one MAD protocol over another, etc.

It sounds like LACP MAD is the most straightforward, but requires the intermediary devices to also be comware, in which case the only interface I can use is the inter-building link between the two IRF systems. Each has a domain ID, so it sounds like that should work. Our other LACP links are to procurve access switches, so presumaby are incompatible with MAD.

The other obvious option would be to add an extra vlan for a dedicated BFD link. Either I'd need to add an extra SFP+ cable between the two switches, or... might it be possible to use the (otherwise unused, by us) GigE management interface for this?

Thanks for any recommendations,

Graham

[paulgear]

Hi Graham,

Can you clarify: are your IRF stacks within the one building, or do you run a single IRF stack across buildings?

[gtallan]

I knew my description was unclear :-) One IRF stack (of two switches) per building.

[paulgear]

Hi Graham,

If you can spare one port on each switch, I would just set up a loopback cable from one to the other and use MAD BFD.  Keep in mind that it's only there to prevent split brain when the IRF is broken, and that shouldn't happen if you've put the right redundancy in your IRF stack.  This is the way my 5500 and 5820 stacks are set up.

[Richard Brodie_1]

It was pointed out to me in another thread that newer Procurve switches (K series firmware) support LACP MAD in the latest firmware.

[gtallan]

Thanks I was hoping to avoid buying a couple more SFP+ cables, though it's not a huge deal to do so if needed. Was hoping to hear I could subvert the copper management interface, but from looking at the docs it does seem too different from a regular interface!

[gtallan]

That's interesting, I should follow up that reference. All our connected procurves are K/KA series so this is another option...

[gtallan]

The thread title for the procurve reference is "IRF MAD LACP capable access switches", btw, should anyone else try following...

Checking out the 3800 firmware, LACP-MAD isn't in the latest public firmware 15.12.0012, but it is referenced in the release notes for "early availability" 15.14.0003 (actual firmware download seems to be password-protected at this time). Looks like the same is true for K-series 5400/3500/etc.