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Tracy Yang (Unlicensed)

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For BGP unnumbered, the next-hop address for each prefix is an IPv6 link-local address, which is assigned automatically to each interface. Using the IPv6 link-local address as a next-hop instead of an IPv4 unicast address, BGP unnumbered saves you from having to configure IPv4 addresses on each interface.

NOTEs:

  • BGP can only be used on two switches with point-to-point connection.
  • BGP unnumbered cannot be used in EVPN underlay.

Configuration Example

Networking Requirements

Figure 1. BGP Unnumbered Configuration Example

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As shown in Figure 1, Switch A and Switch B are BGP peers. An EBGP connection is established between Switch A and Switch B. To save IP addresses, BGP unnumbered can be configured between Switch A and Switch B. In this example, routed interfaces are configured for the use of BGP unnumbered interface.

The only difference between a BGP unnumbered configuration and the BGP numbered configuration is that the BGP neighbor is specified as an interface instead of an IP address. The interface between the two peers does not need to have an IP address configured on each side.

NOTE:

The ebgp-requires-policy function needs to be disabled in EBGP, but not in IBGP.

Procedure

Switch A

Step 1        Enable te-1/1/1 as a routed interface and configure the interface name as r1.

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