Archives for posts with tag: Nexus 7000

One of the interesting design considerations when deploying FabricPath is where to put your layer 3 gateways (i.e. your SVIs). Some people opt for the spine layer (especially in smaller networks), some may choose to deploy a dedicated pair of leaf switches acting as gateways for all VLANs, or distribute the gateway function across multiple leaves. Whatever choice is made, there are a couple of challenges that some have come across.

As you may know, vPC+ modifies the behaviour of HSRP to allow either vPC+ peer to route traffic locally. This is certainly useful functionality in a FabricPath environment as it allows dual active gateways, however what if you want your default gateways on the Spine layer (where there are no directly connected STP devices, and therefore no real need to run vPC+)? What you end up with in this case is vPC+ running on your Spine switches in order to gain access to the dual active HSRP forwarding, but with no actual vPC ports on the switch. This works fine – but most people would prefer not to have vPC+ running on their Spine switches if they can avoid doing so.

Anycast-HSRP-1 Read the rest of this entry »

A question that I still get quite a lot is how to connect Nexus 2000 Fabric Extenders to their parent switches – is it better to single attach them to the parent, or to dual-home the FEX to both parent switches (using vPC)? Of course there is no right answer for every situation – it depends on the individual environment and sometimes personal preference, but here are a few of my thoughts on this. Read the rest of this entry »

On a recent Packet Pushers podcast, use of the Peer-Gateway feature on the Nexus 7000 and whether it resolves the lack of support for L3 over vPC was briefly discussed. The whole topic has been quite a big source of confusion, so let’s answer it straight away: using Peer-Gateway to try and resolve L3 over vPC issues is not supported, but more importantly in most cases it doesn’t actually work. The question is, why not? There are actually two reasons. Read the rest of this entry »

The lack of support for running layer 3 routing protocols over vPC on the Nexus 7000 is well documented – less well known however is that the Nexus 5500 platform operates in a slightly different way which does actually allow layer 3 routing over vPC for unicast traffic. Some recent testing and subsequent discussions with one of my colleagues on this topic reminded me that there is still (somewhat understandably) a degree of confusion around this.

Let’s start with a reminder of what doesn’t work on the Nexus 7000:

L3-over-vPC-5Kvs7K1

Read the rest of this entry »