Design question, interconnecting two 9500 stacks

[NetworkEngineer00237]

Hello,

I am currently setting up a new network at my company and have a question about my design.  We have 2 buildings side by side with fiber between the buildings.  I bought 4 9500's for the core and have set up 2x2 as stackwise stacks for a collapsed core configuration.  My question is, originally, I thought I would do a layer 3 port channel between them and route traffic between buildings but now I'm not so sure.  I was reading about multichassis etherchannel and that seems like it might be the way to go.  There are not separate networks in each building, they use the same vlans.  I might change that in the future but for now, they will be the same.

Each building will have its own internet connectivity and be a backup for the other building and it just seemed logical to use routing but it seems that I can put both virtual domains in an etherchannel and that will serve the same purpose and be more efficient.  Recommendations?  Thanks!

[balaji.bandi]

Worth deploy 2 X stackwise virtual and make them different VLAN segment for their own internet segment.

make sure you have right license to deploy stackwise virtual, if no this require re-design.

[NetworkEngineer00237]

Thank you for the reply.  I have 2 of the switches in stackwise virtual domain 1 and 2 switches in virtual domain 2 so they are configured for stackwise virtual.  Are you saying I need to create a L3 transit vlan between the stacks and route between them?  If so, that was my initial design but it seems that with multichassis etherchannel between the stacks, I wouldn't need to do that.  Is that correct?

[balaji.bandi]

yes for the L3 traffic you like to exchange -

for your stack they stay respected SVL domain and using Transit link to go otehr side ?

make a smalll HLD diagram so you are clear with goals.

[NetworkEngineer00237]

Here is a diagram of how I want the new network to be.  The fiber between buildings is 10g om3 multimode I believe.  either way, L3 connectivity is not required.  I'm just not sure whether I should do L2 or L3 between and how I should configure it

[Scott Hodgdon]

NetworkEngineer00237,

If you are going to directly connect the two SWV , you should make sure they are cross-connected with 4 links. This is the Best Practice for connect two SWV domains. In your picture, you have just 2 connections between the two SWV domains. Whether you use L3 PortChannel or Equal Cost Multi-Path (ECMP) routing between the two domains is up to you. 

Looking at your picture, you should also cross connect your WAN devices to each of the SWV members in a domain instead of connecting each WAN device with two connections to a single member of the SWV domain.

Every device that connects to a SWV domain should connect to each of the SWV domain members if possible.

Cheers,
Scott Hodgdon

Senior Technical Marketing Engineer

Enterprise Networking and Cloud Group

[NetworkEngineer00237]

Thanks for the reply Scott.  So you are saying I should have 2 ports on each switch in each SWV for uplinks to each other?  I will have to look and make sure I have enough fiber pairs.  I should, there should be 6 in the cable.

My diagram must not be clear, I will have 1 port from each switch to go to each firewall.  I tried to color code them so it would be easier to read haha.  I also plan to make those L3 port-channels for redundancy and routing.  I made a rudimentary drawing that may better illustrate what i'm trying to do

[Scott Hodgdon · Accepted solution]

NetworkEngineer00237,

The original diagram was correct with respect to FW to SWV connections. I just looked at it incorrectly.

The connection from SWV 1 to SWV 2 will be 4 links, either using ECMP or L3 Multi-Chassis EtherChannel.

Cheers,
Scott Hodgdon

Senior Technical Marketing Engineer

Enterprise Networking and Cloud Group

[NetworkEngineer00237]

Ok, thank you for your advice, that's what I needed to know.  I have setup a L3 port-channel between the SWV's with routing via ospf and its working but i'm blowing it away and starting over.