bgp default gateway ways

[Mlex1]

Hello everyone i want to configure BGP to send the default route to a neighbor, i receive from ISP full veiw i can't advertise to another peer 0.0.0.0/0.

In lab on EVE, everything works perfectly by the way this step i done for 0.0.0.0/0
ip route 0.0.0.0 0.0.0.0 Null0:
as we know Null0 just for test taking 0.0.0.0/0 the default route is advertised to the intended neighbor as expected.
settings
R01
router bgp 200
bgp log-neighbor-changes
neighbor 10.10.10.2 remote-as 300
neighbor 10.10.10.2 description R03
!
address-family ipv4
network 0.0.0.0
neighbor 10.10.10.2 activate
neighbor 10.10.10.2 route-map RM_DEFAULT out
exit-address-family
!
ip route 0.0.0.0 0.0.0.0 Null0
!
ip prefix-list DEFAULT seq 5 permit 0.0.0.0/0
!
route-map RM_DEFAULT permit 10
match ip address prefix-list DEFAULT
!
R03
router bgp 300
bgp log-neighbor-changes
network 3.3.3.3 mask 255.255.255.255
neighbor 10.10.10.1 remote-as 200
neighbor 10.10.10.1 description R1
!
However, in production, it’s not working, even though the configuration appears to be identical.

[Harold Ritter]

Hi @Mlex1 ,

You do not need to locally generate the default route as you already have it in BGP coming from the ISP. The easiest would be to just propagate this default route to the internal peer. You would set a route-map towards this internal peer denying everything but the default route.

route-map default-only permit 10

match ip address prefix-list default-only

route-map default-only deny 20

ip prefix-lits default-only permit 0.0.0.0/0

router bgp xxx

neighbor <internal peer IP address> route-map default-only out

[Mlex1]

route-map default-only deny 20 by default this step working ? no

other steps same as  my config 

Hello Harold Ritter

currently my config on routers

router bgp 200
neighbor 10.10.10.2 remote-as 300

neighbor 10.10.10.2 description R03
neighbor 192.168.1.2 remote-as 100

neighbor 192.168.1.2 description R1
!
address-family ipv4
neighbor 10.10.10.2 activate neighbor

10.10.10.2 send-community both

neighbor 10.10.10.2 soft-reconfiguration inbound

neighbor 10.10.10.2 route-map RM_DEFAULT out
neighbor 192.168.1.2 activate
exit-address-family
!
router bgp 100
bgp log-neighbor-changes
neighbor 192.168.1.1 remote-as 200

neighbor 192.168.1.1 default-originate

[Harold Ritter]

Hi @Mlex1 ,

Sorry I overlooked your route-map configuration.

My point is that you do not need to configure the network statement to originate the default route locally, as it already received fro m the ISP.

[Mlex1]

if you mean default from R2 advertise to R1 this step i emulate just for 0.0.0.0/0 in production i receive full veiw from ISP 

as it already received fro m the ISP.

and my config looks right?

[Harold Ritter]

Hi @Mlex1 ,

Yes, I understand that R2 emulates the ISP in your test topology and that in your production network you receive the full internet routing table + the default route. 

You config looks good. The route-map propagates the default route to the internal peer and denies everything else. 

[Mlex1]

The route-map propagates the default route to the internal peer and denies everything else. 

as i see don't work my configs i don't know why anyway need troubleshooting on eve i tried everything looks good

[Harold Ritter]

Hi @Mlex1 ,

> as i see don't work my configs i don't know why

Do you mean that it doesn't work in your lab topology or in production?

As I mentioned, if you receive the default from the ISP, propagating it to the internal peer should be fairly easy.