Thursday, May 9, 2019

Cisco Nexus HSRP + Dynamic routing

I'm working on deploying a pair of Nexus 3k Switches to act as the layer 3 core of our network. They are replacing an existing stack of layer 3 Dell switches. But I'm having some trouble wrapping my head around how to get dynamic routing to work.

Topology is:

Edge Switches (layer 2) > Old Dell / new Nexus Pair (Layer 3) > Fortigate Firewall > Internet/MPLS

https://imgur.com/a/cqtlcj6

The Fortigates terminate our MPLS and Internet. All of our LAN VLANs terminate on the Dell stack. There is a dedicated /24 transit network in between the Fortigates and the Layer 3 switches. The Dell stack and the Fortgates share routing updates using RIP.

Because the Nexus switches don't stack I'm running HSRP and VPCs for layer 3 redundancy for our LAN VLAN interfaces.

I can add the transit VLAN to the Nexus switches so that they can send traffic to the Fortigates.

But I assume I can't run HSRP on the transit VLAN and use the virtual IP for the routing protocol?

If I put an interface IP on each Nexus and use that for routing updates, how do I configure the Nexus switches so that the Fortigates know which switch is active and which is passive? Or do I care?



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