Configuring BGP

Starting in FortiSwitchOS 7.2.2, the set ebgp-requires-policy command (under config router bgp) is set to enable by default, which prevents the BGP router from learning or advertising prefixes from or to its eBGP peers.

Configuring BGP on the FortiSwitch unit includes the following major steps:

1. Enter the BGP configuration mode.
2. Set the autonomous system and router identifier.
3. Configure the BGP neighbors.
4. Redistribute non-BGP routes.

   Advertise these non-BGP routes within BGP.

Enter the BGP configuration mode

Enter the BGP configuration mode to access all of the BGP configuration commands:

# config router bgp

Set the autonomous system and router identifier

Set the autonomous system. For iBGP, the AS value needs to match the remote-as value in the neighbor router. For eBGP, the AS value differs from the remote-as value in the neighbor router. You also need to specify a fixed router identifier for the FortiSwitch unit. These two commands are mandatory.

# set as <AS number>

# set router-id <IP_address>

Configure the BGP neighbors

Configure the BGP neighbors.

NOTE: For iBGP, if the IP address of the BGP neighbor is a loopback address, you must use the set update-source cmd command to specify which interface address will be used as the source IP address in the outgoing BGP packet.

config neighbor

edit "<IPv4_or_IPv6 address>"

set remote-as <1-4294967295>

end

Redistribute non-BGP routes

Redistribute non-BGP IPv4 or IPv6 routes within BGP:

config redistribute {connected | isis | ospf | rip | static}

set status enable

set route-map <string>

end

config redistribute6 {connected | isis | ospf | rip | static}

set status {disable | enable}

set route-map <string>

end

Other BGP commands

Clearing the BGP routes

Use the following commands to clear the BGP routes:

execute router clear bgp all

execute router clear bgp ip <IPv4_or_IPv6_address>

execute router clear bgp ipv6 <IPv4_or_IPv6_address>

execute router clear bgp as <AS_number>

execute router clear bgp dampening <IP_address>

Checking the BGP configuration

The get router info bgp and get router info6 bgp commands have options to display different aspects of the BGP configuration and status.

For example:

get router info bgp neighbors

get router info bgp network

get router info6 bgp filter-list

get router info6 bgp route-map

Changing the maximum number of paths for ECMP

If you are using equal-cost multi-path (ECMP) routing with the eBGP or iBGP, the maximum number of paths is 1 by default. Use the following commands to change the default:

config router bgp

set maximum-paths-ebgp <1-64>

set maximum-paths-ibgp <1-64>

end