MP-BGP Route Reflectors

This chapter contains the following sections:

BGP Protocol Peering to External BGP Speakers

ACI supports peering between the border leaves and the external BGP speakers using iBGP and eBGP. ACI supports the following connections for BGP peering:

  • iBGP peering over OSPF

  • eBGP peering over OSPF

  • iBGP peering over direct connection

  • eBGP peering over direct connection

  • iBGP peering over static route


Note

When OSPF is used with BGP peering, OSPF is only used to learn and advertise the routes to the BGP peering addresses. All route control applied to the Layer 3 Outside Network (EPG) are applied at the BGP protocol level.

ACI supports a number of features for iBGP and eBGP connectivity to external peers. The BGP features are configured on the BGP Peer Connectivity Profile.

The BGP peer connectivity profile features are described in the following table.


Note

ACI supports the following BGP features. NX-OS BGP features not listed below are not currently supported in ACI.
Table 1. BGP Peer Connectivity Profile Features

BGP Features

Feature Description

NX-OS Equivalent Commands

Allow Self-AS

Works with Allowed AS Number Count setting.

allowas-in

Disable peer AS check

Disable checking of the peer AS number when advertising.

disable-peer-as-check

Next-hop self

Always set the next hop attribute to the local peering address.

next-hop-self

Send community

Send the community attribute to the neighbor.

send-community

Send community extended

Send the extended community attribute to the neighbor.

send-community extended

Password

The BGP MD5 authentication.

password

Allowed AS Number Count

Works with Allow Self-AS feature.

allowas-in

Disable connected check

Disable connected check for the directly connected EBGP neighbors (allowing EBGP neighbor peering from the loopbacks).

TTL

Set the TTL value for EBGP multihop connections. It is only valid for EBGP.

ebgp-multihop <TTL>

Autonomous System Number

Remote Autonomous System number of the peer.

neighbor <x.x.x.x> remote-as

Local Autonomous System Number Configuration

Options when using the Local AS feature. (No Prepend+replace-AS+dual-AS etc).

Local Autonomous System Number

The local AS feature used to advertise a different AS number than the AS assigned to the fabric MP-BGP Route Reflector Profile. It is only supported for the EBGP neighbors and the local AS number must be different than the route reflector policy AS.

local-as xxx <no-prepend> <replace-as> <dual-as>

Configuring an MP-BGP Route Reflector Using the GUI

Procedure

Step 1

On the menu bar, choose System > System Settings.

Step 2

In the Navigation pane, right-click BGP Route Reflector, and click Create Route Reflector Node Policy EP.

Step 3

In the Create Route Reflector Node Policy EP dialog box, from the Spine Node drop-down list, choose the appropriate spine node. Click Submit.

Note

 

Repeat the above steps to add additional spine nodes as required.

The spine switch is marked as the route reflector node.

Step 4

In the BGP Route Reflector properties area, in the Autonomous System Number field, choose the appropriate number. Click Submit.

Note

 

The autonomous system number must match the leaf connected router configuration if Border Gateway Protocol (BGP) is configured on the router. If you are using routes learned using static or Open Shortest Path First (OSPF), the autonomous system number value can be any valid value.

Step 5

On the menu bar, choose Fabric > Fabric Policies > POD Policies.

Step 6

In the Navigation pane, expand and right-click Policy Groups, and click Create POD Policy Group.

Step 7

In the Create POD Policy Group dialog box, in the Name field, enter the name of a pod policy group.

Step 8

In the BGP Route Reflector Policy drop-down list, choose the appropriate policy (default). Click Submit.

The BGP route reflector policy is associated with the route reflector pod policy group, and the BGP process is enabled on the leaf switches.

Step 9

In the Navigation pane, choose Pod Policies > Profiles > default. In the Work pane, from the Fabric Policy Group drop-down list, choose the pod policy that was created earlier. Click Submit.

The pod policy group is now applied to the fabric policy group.

Configuring an MP-BGP Route Reflector for the ACI Fabric

To distribute routes within the ACI fabric, an MP-BGP process must first be operating, and the spine switches must be configured as BGP route reflectors.

The following is an example of an MP-BGP route reflector configuration:


Note
In this example, the BGP fabric ASN is 100. Spine switches 104 and 105 are chosen as MP-BGP route-reflectors. 

apic1(config)# bgp-fabric
apic1(config-bgp-fabric)# asn 100
apic1(config-bgp-fabric)# route-reflector spine 104,105

Configuring an MP-BGP Route Reflector Using the REST API

Procedure

Step 1

Mark the spine switches as route reflectors.

Example:

POST https://apic-ip-address/api/policymgr/mo/uni/fabric.xml

<bgpInstPol name="default">
  <bgpAsP asn="1" />
  <bgpRRP>
     <bgpRRNodePEp id=“<spine_id1>”/>
     <bgpRRNodePEp id=“<spine_id2>”/>
  </bgpRRP>
</bgpInstPol>

Step 2

Set up the pod selector using the following post.

Example:

For the FuncP setup— 

POST https://apic-ip-address/api/policymgr/mo/uni.xml

<fabricFuncP>
  <fabricPodPGrp name="bgpRRPodGrp”>
    <fabricRsPodPGrpBGPRRP tnBgpInstPolName="default" />
  </fabricPodPGrp>
</fabricFuncP>

Example:

For the PodP setup— 

POST https://apic-ip-address/api/policymgr/mo/uni.xml

<fabricPodP name="default">
  <fabricPodS name="default" type="ALL">
    <fabricRsPodPGrp tDn="uni/fabric/funcprof/podpgrp-bgpRRPodGrp"/>
  </fabricPodS>
</fabricPodP>

Verifying the MP-BGP Route Reflector Configuration

Procedure

Step 1

Verify the configuration by performing the following actions:

  1. Use secure shell (SSH) to log in as an administrator to each leaf switch as required.

  2. Enter the show processes | grep bgp command to verify the state is S.

    If the state is NR (not running), the configuration was not successful.

Step 2

Verify that the autonomous system number is configured in the spine switches by performing the following actions:

  1. Use the SSH to log in as an administrator to each spine switch as required.

  2. Execute the following commands from the shell window

    Example:

    cd /mit/sys/bgp/inst

    Example:

    grep asn summary
The configured autonomous system number must be displayed. If the autonomous system number value displays as 0, the configuration was not successful.