Need help with network design

[dilu]

Hello,

I am currently trying to find/test the best solution for the network below:

Switch X670-1,2,3 and 4 are already in use, switch X670-5 and 6 are new.
1,2,3 and 4 are currently connected with MLAG.

X670-1 and 2 are present on one site.
X670-3 and 4 are present on one site.
X670-5 and 6 are present on one (new) site.

I have the above set up in a testlab.

Should i configure EAPS or ERPS for this setup or can is simply use MLAG?
I am afraid i will get loops if I connect the switches like this.

Can anyone give me some tips how i can do this the most effectively.

[Chad_Smith1]

When you use EAPS, you always have to contend with the fact that you have a link blocked. This can cause certain inefficiencies. However, you do have control over what port is blocked. So if you want to ensure traffic from 1 to 3 doesn't have to go through 5 and 6 you can ensure that the normally blocked port is between 3 and 6. You can also "load share" with EAPS using multiple rings on the same physical topology. Lets say you have VLAN A and VLAN B and both send equal amounts of traffic. You can create an EAPS ring for VLAN A that is blocked on the switch 3-6 connection and an EAPS ring for VLAN B that is blocked on switch 1-5 connection. This allows both links to be utilized for traffic transmission.

[dilu]

Hello Patrick, Chad and Brandon,

First off all thank you for the extensive replies, it really helps me understand
the options.

I like the “Stacks with MLAG” design from Chad, although Brandon is right:
1 and 2 are in building 1.
3 and 4 are in building 2.
5 and 6 are in building 3.

The fact is that the most traffic (90%) will flow from building 1 (switch 1,2) to building 2 (switch 3 and 4).

The one thing i don’t understand from EAPS, will i get the full bandwith from the uplinks or will
for example traffic from switch 1 to switch 3 flow “through” 5 and 6?
This does not seem very effective right?

Thanks again for all your help.

[Chad_Smith1]

dilu,

Unfortunately, the inability to change the connections limits the options. If we are looking for the "best" option, and stacking is a possibility, I think the following topology would be preferred:

Otherwise, an EAPS topology may be the next best option (this would require the MLAG configuration to be removed):

Any other combination that I can think of, without changing physical connections, would either be non-ideal or not supported.

[BrandonC]

One caveat to the first (MLAG) design. It looks like X670-1/2 are in one building, and X670-3/4 are in another.

If this is the case, it may be better to use EAPS, so that the ISC will not be used heavily for user traffic. You could either use the EAPS topology that Chad showed, or a single EAPS ring between three stacks (one at each site).