MP-BGP Definitions

  • MP-BGP is the protocol leveraged by ACI fabric nodes to propagate learned external routes into the fabric.
  • MP-BGP and iBGP use the same Autonomous System Number (ASN)
  • runs on all fabric nodes (leafs and spines) to propagate routing information received from external routes within the fabric.
  • It is optional to configure one spine as a MP-BGP Route Reflector, which simplifies BGP route propagation. Ideally configure more than one spine for this role for redundancy purposes. The fabric nodes receiving routes from the Route Reflector are called Route Reflector clients.
  • carries endpoint reachability information between pods.

If a BGP Route Reflector is configured, then:

  • the border leaf peers with each Route Reflector using iBGP

else:

  • the border leaf peers with all BGP speakers in the Autonomous System using iBGP. The ASN is configured under the Route Reflector configuration page.

MP-BGP Configuration

Create a BGP Route Reflector Policy

Go to System –> System Settings. Then under Quota click on BGP Route Reflector

Then I specify the BGP AS number:

I invoke the Route Reflector Node menu to add at least one route reflector node:

I add the spine as a Route Reflector Node.

OK and Submit.

Create a Pod Policy Group

Go to Fabric -> Fabric Policies -> Pods -> Policy Groups

in BGP Route Reflector Policy, choose the previously created Route Reflector policy:

Create a Pod Profile

Go to Pods -> Profiles

Give a name to the Pod Profile:

We must now add a Pod Selector.

We can either:

  • include all Pods in the same Pod Selector, or
  • create a range of Pods in a same Pod Selector, or
  • create a one to one mapping between Pods and Pod Selectors (one Pod <-> one Pod Selector):

Associate a Pod Policy Group to the Pod Profile. We leverage in this example the previously created Pod Policy Group df_Pod_PolG:

Displaying the BGP Neighbors

this is performed under Fabric -> Inventory -> Pod -> {select the node} -> Protocols -> BGP -> BGP for VRF-overlay-1 -> Neighbors.

You can also use the CLI to display BGP neighbors, for example on a spine:

spine# show ip bgp neighbors vrf all

The same result is possible with GUI too.

Categories: Cisco DCACI

Keyboard Banger

Keyboard Banger is a network engineer from Africa. He has been working in network support and administration since 2008. He started writing study notes about certification exams and technology topics a couple of years ago. When he's not writing articles, he can be found wandering on technical forums.

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