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The following is a simple BGP configuration with no additional settings and neighbor information:
config router bgp
config neighbor
edit "10.109.49.20"
set remote-as 65001
next
end
end
For example, the following directly connected networks are in the routing table:
get router info routing-table all
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
V - BGP VPNv4
* - candidate default
Routing table for VRF=0
S* 0.0.0.0/0 [10/0] via 10.109.63.254, mgmt, [1/0]
C 10.109.16.0/20 is directly connected, port1
C 10.109.48.0/20 is directly connected, mgmt
When advertising the 10.109.16.0/20 network using a different subnet (/16 in this example), the following will be seen:
config router bgp
config network
edit 1
set prefix 10.109.0.0 255.255.0.0
next
end
end
get router info bgp neighbors 10.109.49.20 advertised-routes
% No prefix for neighbor 10.109.49.20
get router info bgp network
In this case, there are two options:
- While using the 'network' command, the prefix should be exactly the same as the one in the routing table. It will be necessary to make the following changes for the network to be advertised:
config router bgp
config network
edit 1
set prefix 10.109.16.0 255.255.240.0
next
end
end
get router info bgp neighbors 10.109.49.20 advertised-routes
VRF 0 BGP table version is 1, local router ID is 10.109.49.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight RouteTag Path
*>i10.109.16.0/20 10.109.49.1 100 32768 0 i <-/->
Total number of prefixes 1
get router info bgp network
VRF 0 BGP table version is 1, local router ID is 10.109.49.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight RouteTag Path
*> 10.109.16.0/20 0.0.0.0 100 32768 0 i <-/1>
Total number of prefixes 1
- If the plan is for the subnet to be advertised with /16 prefix, it will be necessary to use the 'aggregate-address' option:
config router bgp
config aggregate-address
edit 1
set prefix 10.109.0.0 255.255.0.0
set summary-only enable
next
end
end
get router info bgp neighbors 10.109.49.20 advertised-routes
VRF 0 BGP table version is 2, local router ID is 10.109.49.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight RouteTag Path
*>i10.109.0.0/16 10.109.49.1 100 32768 0 i <-/->
Total number of prefixes 1
get router info bgp network
VRF 0 BGP table version is 2, local router ID is 10.109.49.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight RouteTag Path
*> 10.109.0.0/16 0.0.0.0 32768 0 i <-/1>
s> 10.109.16.0/20 0.0.0.0 100 32768 0 i <-/1>
Here, the ‘s’ in front of the /20 network indicates this route is suppressed by BGP.
Related article:
Technical Tip: How to implement BGP route summary (aggregation) on a FortiGate
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