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So practising bgp on eve ng, have an issue

kbk989
Level 1
Level 1

So i have the following topology-

kbk989_0-1756476397708.png
ISP-RT-1 has a default route pointing to 192.168.20.1

Image being used is - vios-adventerprise9-m.SPA.159-3.M6

Some show commands-


ISP-RT-1#show ip bgp 0.0.0.0
BGP routing table entry for 0.0.0.0/0, version 2
Paths: (1 available, best #1, table default)
Advertised to update-groups:
3
Refresh Epoch 1
Local
192.168.20.1 from 0.0.0.0 (1.1.1.1)
Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced, local, best
rx pathid: 0, tx pathid: 0x0

Now im trying to aadvertise this to the 3 ibgp peers (1 of them not shown in the pic but its just a direct point to point) and it doesnt work at all-

ISP-RT-1#show running-config | section bgp
router bgp 65312
bgp log-neighbor-changes
network 0.0.0.0
neighbor 65.30.24.1 remote-as 65312
neighbor 65.30.24.5 remote-as 65312
neighbor 65.30.24.9 remote-as 65312

ISP-RT-1#show ip bgp summary
BGP router identifier 1.1.1.1, local AS number 65312
BGP table version is 2, main routing table version 2
1 network entries using 144 bytes of memory
1 path entries using 84 bytes of memory
1/1 BGP path/bestpath attribute entries using 160 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 388 total bytes of memory
BGP activity 1/0 prefixes, 1/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
65.30.24.1 4 65312 9 10 2 0 0 00:04:59 0
65.30.24.5 4 65312 9 11 2 0 0 00:04:49 0
65.30.24.9 4 65312 9 11 2 0 0 00:04:37 0

If i look at the routing table on say ISP-RT-2 it doesnt learn the default route, what am i doing wrong?

ISP-RT-2#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, 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, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is not set

2.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 2.2.2.0/24 is directly connected, Loopback0
L 2.2.2.2/32 is directly connected, Loopback0
65.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 65.30.24.0/30 is directly connected, GigabitEthernet0/1
L 65.30.24.1/32 is directly connected, GigabitEthernet0/1

Its the same on the other 2 routers as well and they do not learn the default route, so yeah no idea whats going on.
Ive researched online and everywhere i look they say all i need is a "network 0.0.0.0" statement which i tried as you can see but yeah doesnt work.

Thank You

2 Accepted Solutions

Accepted Solutions

Martin L
VIP
VIP

MartinL_0-1756714635677.png

from CCIE v5 vol. 2 by Narbik, Vinston, Cisco Press. 

Regards, ML
**Have fun labbing!!!***
***Please Rate All Helpful Responses ***  

View solution in original post

In this video, learn how to advertise default routes in Border Gateway Protocol (BGP) to optimize your network routing. We'll guide you through the steps and best practices for configuring BGP to advertise default routes, ensuring seamless routing and connectivity in large-scale networks. Related
17 Replies 17

You need to use defualt information originate under bgp.

MHM

so yeah i tried that too and it doesnt work, could it have something to do with the image im using? i do have a csr1000v image as well which i can use.

Bgp advertise 0.0.0.0 only if this appear in RIB 

Can i see 

Show ip route 

MHM

yes it does have it-

ISP-RT-1#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, 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, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR

Gateway of last resort is 192.168.20.1 to network 0.0.0.0

S* 0.0.0.0/0 [254/0] via 192.168.20.1
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/24 is directly connected, Loopback0
L 1.1.1.1/32 is directly connected, Loopback0
65.0.0.0/8 is variably subnetted, 6 subnets, 2 masks
C 65.30.24.0/30 is directly connected, GigabitEthernet0/1
L 65.30.24.2/32 is directly connected, GigabitEthernet0/1
C 65.30.24.4/30 is directly connected, GigabitEthernet0/2
L 65.30.24.6/32 is directly connected, GigabitEthernet0/2
C 65.30.24.8/30 is directly connected, GigabitEthernet0/3
L 65.30.24.10/32 is directly connected, GigabitEthernet0/3
192.168.20.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.20.0/24 is directly connected, GigabitEthernet0/0
L 192.168.20.106/32 is directly connected, GigabitEthernet0/0

192.168.20.1 <<- this IP reachable via other ibgp neighbors

MHM

If this IP not know 

Use next-hop self 

Abd network 0.0.0.0 under bgp

MHM

ah ok ill try next hop self

M02@rt37
VIP
VIP

Hello @kbk989 

Because the static default is not present in the routing table, the network 0.0.0.0 statement in BGP has no effect...

=> so nothing is advertised to your iBGP peers.

 

Best regards
.ı|ı.ı|ı. If This Helps, Please Rate .ı|ı.ı|ı.

i see makes sense

Still not get defualt in ibgp?

MHM

Show ip bgp neighbors x.x.x.x advertise <<- share this in router 

Show ip bgp neighbors x.x.x.x receive <<- share this in remote router 

Share debug ip bgp update after you clear ip bgp process for both router and remote one

MHM

Martin L
VIP
VIP

is it working now? Book by W. Odom CCIE v4 RS has a summary table that shows 3 ways to advertised default route under bgp. I recommend his book. (topic replicated into CCIE v5 RS book I think) 

Regards, ML
**Have fun labbing!!!***
***Please Rate All Helpful Responses ***  

next hop issue how I know that ?

ISP-RT-1#show ip bgp 0.0.0.0
BGP routing table entry for 0.0.0.0/0, version 2
Paths: (1 available, best #1, table default)
Advertised to update-groups:
3
Refresh Epoch 1
Local
192.168.20.1 from 0.0.0.0 (1.1.1.1)
Origin IGP, metric 0, localpref 100, weight 32768, valid, sourced, local, best
rx pathid: 0, tx pathid: 0x0

solution is next hop self 

Screenshot (1020).pngScreenshot (1021).pngScreenshot (1022).pngScreenshot (1023).pngScreenshot (1024).pngScreenshot (1025).png

NOTE:- use debug ip bgp update next time in trouble 
NOTE:- clear ip bgp <<- when you add or remove any command of BGP

MHM

other solution 
use 
neighbour x.x.x.x default-information <<- under R2 (router have static default route)

Screenshot (1029).pngScreenshot (1030).png