question topology stack

[daac84]

Hello

could someone please make me a question, I have a scenario like the image, the red line means is in stack.

According to the scenario each have connections ABCD switch core team A and B by LACP for redundancy, and are passing them each vlans,

My question is whether despite using an LACP on these connections it might be inconvenient to rstp considering we are in the ABCD switch stack.


thanks

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[devnull]

I don not really understand what you want to say.
You have a stack constisting of 4 Slots and this stack is connected by LACP (4*1G or 4*10G) to each Core switch?!

You will need to run some kind of STP (RSTP, 1x1, MSTP) to avoid a loop.
This means that probably one of yoir LACP will be in STP blocking.
You could only avoid that if the Coreswitche would be a VC/MC-LAG, hence you have a single LACP from you stack going to the VC.

But also in this case running stp is probably a good idea, as this will rule out any issues with someone adding redundant pathes by error.

edit: i hope you have a closed stacking loop -> stack cable from A to D as well

[daac84]

Hello

I'm trying to say is that if I have lacp to the core, from each of the switch stack (two ports from each switch (ABCD) to core, one A and one at B forming LACP), they behave as one having only one functioning lacp by stp issues.

something like the image where only one path is active (considering if I set stp priority issues on the core sw.)

[devnull]

I think you got it wrong.

LACP means bundeling multiple links into one logical.

Hence you have from your Stack (which is logical a single device) one link to each of the Core.
one of these LACP-Links (logical) will be blocked.
The LACP to the root bridge will be active (at least if the interface speeds are the same)

But i am still missing your initial question.

[daac84]

Ok thanks for the reply but I saw the connection differently but basically I think would have the same result as your explanation (picture 1)


Well I can think of that could be grouped in eight interfaces for not handle stp lacp (according OmniSwitch 6450 documentation stand it), my question is if I can be grouped by theme stack, for example 4 switch in stack

1 and 2 port switch A (slot1) 1/1/1 and 1/1/2
1 and 2 port switch B (SLOT2) 2/1/1 and 2/1/2 ALL IN ONE AGAINST A LACP
1 and 2 port switch C (SLOT3) 3/1/1 and 3/1/2 LACP IN THE CORE
1 and 2 port switch D (SLOT4) 4/1/1 and 4/1/2

Thanks

[devnull]

Ich you have a stack you can of course use ports on different stack members inside a single lacp.

so lag1 with ports 1/1, 2/1, 3/1, 4/1
and lag2 with ports 1/2, 2/2, 3/2, 4/2
ist perfectly fine.

A single LAG MUST end on a single device (either physical = Core1 or Logical e.g. other stack OR VC)

So picture2 does not work as you have seperate Coreswitches without VC -> no single LACP possible.
Picture 1 is wrong as you still have lacps towards two different (Core1&2) devices. Thats not the way it works.

In case of my pictúre the LAG to the Root is forwarding, the lag to the other Core is blocking (hence no ports in that LAG transport data).
With 1x1 and different rootbridges you could have different vlans on each LAG forwarding or blocking but i guess you should get the basics sorted out first.