L3 Port-Channel vs. L3 Physical Ports

[zekebashi]

 Hello,

The attached design depicts two solutions:

1. The first one shows a pair of NX9Ks configured in a vPC and uplinked to a single upstream C3560 switch using a bundle or 4 physical ports to form a L3 port channels
2. The second design shows a pair NX9Ks configured in a vPC and uplinked to a single upstream C3560 switch using two stand-alone L3 physical ports from each vPC

My question is which solution is the recommend solution when connecting two switches; whether these two switches are configured in a vPC, VSS, or even 802.q, to a single upstream switch. In my design, I've the two NX9Ks configured in a vPC. The upstream switch is running eigrp and the two downstream switches are also running eigrp and establish adjacency to the upstream switch. 

Now, which solution is the recommended solution and why? Can you also provide some cisco documentation?

Thanks in advance, ~zK

[balaji.bandi]

Either case you have only one upstream switch C3560 - so there is no redundancy here if the hardware failures.

if you do not have option and you only going with exiting setup with C3560

i prefer below option- At least you have redundancy on nexus side, if one of nexus fails other will be able to pass the traffic.

- The second design shows a pair NX9Ks configured in a vPC and upstream to a single upstream C3560 switch using two stand-alone L3 physical ports from each vPC

best approach is  you need 2 switches on north side (uplink switches)  connected mesh network with  Nexus switches for more resilience and high availability

[zekebashi]

Thanks for the input. Actually, we've a good reason as to why we currently have a single sw at the dist layer. We'll be replacing this single sw with dual NX9Ks which will also be configured in a vPC.

You mentioned that you prefer the second option. Is there a reason why you prefer dual L3 physical links on each vPC switch rather than L3 Port-channel (bonding 4 physical interfaces)?

Thanks, ~zK

[balaji.bandi]

 L3 Port-channel (bonding 4 physical interfaces)?  - If you do this with on Nexus 9K,  if that nexus 9K switch go down, you do not have resilient connection. instead i prefer and suggested example :

Nexus 9K 1 -------(2 x 1GB) up-link switch

Nexus 9K 2 -------(2 X1GB) up-link switch

[zekebashi]

Sorry, I don't seem to understand your suggestion. " If you do this with on Nexus 9K."

We are considering to up-link two NX9Ks to a single C3560G.

If we bundle 4x1Gbps in a L3 port-channel, this will provide higher bandwidth and load-sharing to each NX9K (downstream switch). If this port-channel were to fail, then the C3560G(upstream switch) will forward traffic through the other L3 Port-channel, which encompasses 4x1Gbps (higher bandwidth than individual 2x1G L3 physical interfaces).

So, either solution does provide redundancy in terms of the up-links from the NX9Ks to the upstream switch, but the question is what is the best practice or recommended solution??

Thanks in advance, ~zK

[balaji.bandi]

I was in impression you are connecting all 4 X  1G link from one Nexus 9K to upstream switch.

if you connecting to both nexus 9K, that is the best suggested setup.