LACP/LAG with 'switches in between' (not true 2-Tier)?

[Frank]

I'm drawing a blank as to "do I do this right, or what do I do wrong?". If you look at the following:

Note that there is no ISC/MLAG between the two 460s.

Coworker and I are debating if the two ports on the Cisco stack need to be put in a LACP/channel-group or not. Neither of us has good enough arguments or detailed enough knowledge as to what exactly is happening, so if anyone could help, that'd be awesome!

- Is the above design reasonable/unreasonable/plain wrong?
- Do the Cisco ports need to be configured as two regular normal trunked/tagged ports, or do they need to be configured as channel/lacp/shared ports?
- or would they only need to be lacp ports if (and only if) the 460s would get an ISC/MLAG between them?

At this point I'm not sure if I could be trusted to connect two tin cans with a string!

Thanks for you help,

Frank

[Erik_Auerswald]

Cisco supports ERPS on Metro Ethernet switches (MExxxx), the 7600 router and some ASRs. I would not expect the unnamed Cisco switches considered here to support it.

The interaction of MLAG and ERPS on the BD8ks could be interesting, indeed.

[BrandonC]

Even with G.8032, you would need a ring topology and I'm not sure how that would work out with the MLAG between the X460s and BD8ks. I've never tried to set something like that up, but I would be hesitant to put it into production.

That said, I think that in theory you should be able to exclude the 8ks from the ERPS config and just run CFM on the LAGs up from both 460s, ignoring the 8ks in the ERPS ring.

[Frank]

OK, I see that a standard 2-Tier-MLAG design is the best solution - and it'd require the Cisco ports to be in a channel/LACP group.
That being said, how would you skin that particular cat if you couldn't MLAG the 460s? Would I have to use Spanning-Tree to ensure no loops? Or is there another option?

[Frank]

Sweet! Yes, that!!!

[Stephane_Grosj1]

On Cisco you should have a feature like "flexlink", or something like that. It will make one of your link active and the other one standby. Once the active link fails, the standby kicks in. This is purely local to the switch.

On Extreme we have it called Software Redundant Port, and with some option it can converge fast.