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]

Hi Frank,

if (or when) you are migrating this to MLAG, you should consider the interaction of MLAG with STP, because Cisco uses STP by default, including Port-Channels. (STP is disabled with FlexLink.) See the GTAC Knowledge article Can I combine MLAG and STP.

If you do combine STP and MLAG (not supported on EXOS) you need to disable EtherChannel Guard on the Cisco, because the EXOS devices will act as independent switches regarding STP.
no spanning-tree etherchannel guard misconfigI recommend to always use LACP for port sharing (LAG, Port-Channel) to guard against cabling errors.

Erik

P.S. The network diagram does not look correct, the two ports on each individual BD8k should not be in a sharing group, but one port of each BD8k should be together in an MLAG (with single port LAGs for LACP).

[Frank]

Erik,
Snaps, you are correct! The ports from the BD to the two different 460s are indeed NOT in a shared group. Paint fail, thanks for catching that!

(I guess in my drawing I already wanted to do a 2-tier mlag!)

[Frank]

Thank you so much for shedding light on this. Active/Passive/Flexlink is probably what I'll put up there for now, with going for a 2-Tier-MLAG in the future.

And this is why "The Hub" is awesome!

[EtherMAN]

Do the cisco support 8032/RPS ... Similar to EAPS but supported by more vendors. Spanning tree to me will always be last resort. Hate the idea of flooding the network when you re-converge your network after a failure. Brings back so many bad memories ::)