Technical Tip: Usage of the 'set capability-dynamic' command

Description

This article describes the effect of the 'set capability-dynamic' command.

Scope

FortiGate.

Solution

The set capability-dynamic command configured on FortiGate under the BGP section for a specific neighbor enables or disables the advertisement of the BGP Dynamic Capability to a BGP neighbor.

Enabling it allows routers to dynamically negotiate capabilities (like new address families or route filtering) or handle capability changes without fully tearing down the BGP session.

Syntax:

artemis-kvm83 # config router bgp
artemis-kvm83 (bgp) # config neighbor 
artemis-kvm83 (neighbor) # edit 10.109.49.8 
artemis-kvm83 (10.109.49.8) # set capability-dynamic 
enable     Enable setting.
disable    Disable setting.

Note:

The default value is disabled.

artemis-kvm83 # config router bgp
artemis-kvm83 (bgp) # config neighbor 
artemis-kvm83 (neighbor) # edit 10.109.49.8 
artemis-kvm83 (10.109.49.8) # sh full | grep dynamic
        set capability-dynamic disable

Note:

If only one BGP peer advertises Dynamic Capability, bidirectional support must not be assumed. The supported operations depend on the capabilities advertised by each peer.


To verify whether the remote BGP peer also supports and advertises Dynamic Capability.

Run the following command:

get router info bgp neighbors <neighbor-ip>