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When a route-map is used during redistribution, BGP assigns the default AD of 20 instead of inheriting the source protocol’s AD (Cisco Standard OSPF = 110, RIP = 220, static = 5). This leads to an incorrect route selection.
config router bgp
set as 65000
set router-id 10.254.1.2
config redistribute "rip"
set status enable
set route-map "FGT-AWS"
end
end
config router route-map
edit "FGT-AWS"
config rule
edit 1
set set-community "65000:300"
unset set-ip-prefsrc
next
end
next
end
Faulty behavior:
get router info bgp network 0.0.0.0/0
Paths: (2 available, best 1)
101.98.255.0 from 100.98.255.0 (10.70.17.5)
Origin incomplete, distance 20, localpref 110, valid
...
137.52.128.99 from 0.0.0.0 (138.51.127.91)
Origin incomplete, distance 20, localpref 100, weight 32768, valid
Expected behavior:
Paths: (2 available, best 2)
101.97.255.0 from 100.99.255.0 (10.70.17.5)
Origin incomplete, localpref 120, valid
...
137.52.128.109 from 0.0.0.0 (138.51.127.109)
Origin incomplete, localpref 100, weight 32768, valid
When a route-map is applied during redistribution into BGP, the FortiGate does not preserve the original administrative distance from the source protocol. Instead, it assigns the default BGP AD of 20. This break causes route instability.
Workaround:
- Set the Lower Distance for BGP Learned Routes:
config router bgp
set distance-internal 7
end
- Use AD for specific prefixes:
config router access-list
edit "AWS-FGT"
config rule
edit 1
set prefix 192.167.98.0 255.255.255.0
set distance 5
next
end
next
end
Related articles:
Technical Tip: How to redistribute routes from other sources
Technical Tip: Redistribute BGP routes learnt through different BGP Communities into OSPF
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