Description
This article describes how to change BGP parameters when advertising default-route (0.0.0.0/0) with the command 'set capability-default-originate enable'.
For a default route advertised using set capability-default-originate enable, the standard route-map used for all advertised prefixes will not work.
Solution
FGT1 < eBGP > FGT2.
From FGT2 prefixes are advertised to FGT1 including a default-route. As-path prepend is required for all routes advertised by FGT2.
FGT2 (root) # show router bgp
config router bgp
set as 65000
set router-id 2.2.2.2
config neighbor
edit "10.109.16.85"
set capability-default-originate enable
set soft-reconfiguration enable
set remote-as 65001
set route-map-out "prepend_all"
next
end
config network
edit 1
set prefix 2.2.2.2 255.255.255.255
next
end
end
FGT2 (root) # show router route-map
config router route-map
edit "prepend_default_route"
config rule
edit 1
set match-ip-address "default_route_only"
set set-aspath "65000 65000"
next
end
next
edit "prepend_all"
config rule
edit 1
set match-ip-address "any_prefix"
set set-aspath "65000 65000 65000 65000"
next
end
next
end
FGT2 (root) # show router prefix-list
config router prefix-list
edit "any_prefix"
config rule
edit 1
set prefix any
unset ge
unset le
next
end
next
Status on FGT1:
FGT1 # get router info bgp neighbors 10.109.16.62 received-routes
BGP table version is 9, local router ID is 1.1.1.1
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
*> 0.0.0.0/0 10.109.16.62 0 0 65000 i <-/->
*> 2.2.2.2/32 10.109.16.62 0 0 65000 65000 65000 65000 65000 i <-/->
Total number of prefixes 2
Subnet 2.2.2.2 is received with the correct as-path, but for the default-route no AS-path prepend was added.
The solution is to use the option 'default-originate-routemap' that will appear in CLI once capability-default-originate is enabled.
FGT2 (root) # show router prefix-list
config router prefix-list
edit "default_route_only"
config rule
edit 1
set prefix 0.0.0.0 0.0.0.0
unset ge
unset le
next
end
next
end
FGT2 (root) # show router route-map
config router route-map
edit "prepend_default_route"
config rule
edit 1
set match-ip-address "default_route_only"
set set-aspath "65000 65000"
next
end
next
FGT3 (root) # show router bgp
config router bgp
set as 65000
set router-id 2.2.2.2
config neighbor
edit "10.109.16.85"
set capability-default-originate enable
set soft-reconfiguration enable
set default-originate-routemap "prepend_default_route" ---> Adding the prepend here.
set remote-as 65001
set route-map-out "prepend_all"
next
end
Status on FGT1 after adding the route-map using default-originate-routemap:
FGT1 # get router info bgp neighbors 10.109.16.62 received-routes
BGP table version is 9, local router ID is 1.1.1.1
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
*> 0.0.0.0/0 10.109.16.62 0 0 65000 65000 65000 i <-/->
*> 2.2.2.2/32 10.109.16.62 0 0 65000 65000 65000 65000 65000 i <-/->
Total number of prefixes 2
As shown in the above output, for default route as-path has been added as configured in the route-map.
