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Beginner

BGP route propogation

Hello Experts

Attached is the configuration of my routers.

I have configured iBGP between the routers and advertised the loopback. But my loopbacks are not getting advertised.

following is the output from my 2 routers:-

Rack1R1#sh ip bgp summ

BGP router identifier 150.1.1.1, local AS number 100

BGP table version is 1, main routing table version 1

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

155.1.23.2      4   100     140     140        1    0    0 00:41:03        0

155.1.23.3      4   100     136     137        1    0    0 01:29:47        0

155.1.45.5      4   100     133     134        1    0    0 01:30:18        0

155.1.146.4     4   100     139     139        1    0    0 01:30:17        0

155.1.146.6     4   100     130     131        1    0    0 01:30:17        0

Rack1R1#sh ip bgp

Rack1R1#sh ip route

Codes: 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

Gateway of last resort is not set

     155.1.0.0/24 is subnetted, 9 subnets

C       155.1.146.0 is directly connected, FastEthernet2/0

D       155.1.23.0 [90/2681856] via 155.1.13.3, 00:35:22, Serial0/1

C       155.1.13.0 is directly connected, Serial0/1

C       155.1.0.0 is directly connected, Serial0/0.1

D       155.1.5.0 [90/2172416] via 155.1.0.5, 00:35:21, Serial0/0.1

D       155.1.58.0 [90/2172416] via 155.1.0.5, 00:35:21, Serial0/0.1

D       155.1.45.0 [90/2172416] via 155.1.146.4, 00:35:21, FastEthernet2/0

D       155.1.37.0 [90/2172416] via 155.1.13.3, 00:35:24, Serial0/1

D       155.1.67.0 [90/284160] via 155.1.146.6, 00:35:24, FastEthernet2/0

     150.1.0.0/24 is subnetted, 1 subnets

C       150.1.1.0 is directly connected, Loopback0

====================================================================================

Rack1R2#sh ip bgp summ

BGP router identifier 150.1.2.2, local AS number 100

BGP table version is 1, main routing table version 1

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd

155.1.13.1      4   100      45      45        1    0    0 00:41:50        0

155.1.23.3      4   100     134     134        1    0    0 02:11:12        0

155.1.45.5      4   100     130     130        1    0    0 02:06:52        0

155.1.146.4     4   100     133     133        1    0    0 02:09:08        0

155.1.146.6     4   100     128     128        1    0    0 02:04:18        0

Rack1R2#sh ip bgp

Rack1R2#sh ip route

Codes: 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

Gateway of last resort is not set

     155.1.0.0/24 is subnetted, 9 subnets

D       155.1.146.0 [90/2684416] via 155.1.23.3, 00:34:38, Serial0/1

                    [90/2684416] via 155.1.0.5, 00:34:38, Serial0/0.1

C       155.1.23.0 is directly connected, Serial0/1

D       155.1.13.0 [90/2681856] via 155.1.23.3, 00:34:38, Serial0/1

C       155.1.0.0 is directly connected, Serial0/0.1

D       155.1.5.0 [90/2172416] via 155.1.0.5, 00:34:38, Serial0/0.1

D       155.1.58.0 [90/2172416] via 155.1.0.5, 00:34:38, Serial0/0.1

D       155.1.45.0 [90/2681856] via 155.1.0.5, 00:34:39, Serial0/0.1

D       155.1.37.0 [90/2172416] via 155.1.23.3, 00:34:39, Serial0/1

D       155.1.67.0 [90/2710016] via 155.1.23.3, 00:34:39, Serial0/1

                   [90/2710016] via 155.1.0.5, 00:34:39, Serial0/0.1

     150.1.0.0/24 is subnetted, 1 subnets

C       150.1.2.0 is directly connected, Loopback0

what could be the issue.

1 ACCEPTED SOLUTION

Accepted Solutions
Highlighted

you have /32 advertised under bgp network statement..

network 155.1.1.1 mask 255.255.255.255

but the routing table entry is /24  or some other mask (not really sure)

150.1.0.0/24 is subnetted, 1 subnets

C       150.1.1.0 is directly connected, Loopback0

the network statement should have an exact match on the routing table (via igp or static or connected routes) in order to advertise...

to correct this, either change loopback to /32 or

change the mask on the network command to /24...it's your choice

Regards Vinayak

View solution in original post

5 REPLIES 5
Highlighted
Rising star

Hi

configs which you have attached can not be opened.

From outputs which you have provided we can see that all bgp peers are in same AS 100. What does topology look like? Did you configure iBGP full mesh?

Try theese commands:

#debug ip bgp update - to see BGP updates and maybe reason why they are denied

#show ip bgp neighbors IP_ADDRESS advertised-routes - show what prefixes are sent to defined neighbor if any

Best Regards

Please rate helpful posts

Best Regards Please rate all helpful posts and close solved questions
Highlighted
Beginner

Hi,

The attachments can't be opened. Can I know how the networks are being advertised. Is it by using network command. If so check whether the subnet mask in the network command is same as the subnet mask in Routing table.

Share sh ip bgp | sec bgp  or sh ip bgp | beg bgp    outputs also.

Please check this and let me know.

Highlighted

Hello

The networks are advertised using network statments.

RACK1R1#

!

router bgp 100

no synchronization

bgp log-neighbor-changes

network 155.1.1.1 mask 255.255.255.255

neighbor 155.1.23.2 remote-as 100

neighbor 155.1.23.3 remote-as 100

neighbor 155.1.45.5 remote-as 100

neighbor 155.1.146.4 remote-as 100

neighbor 155.1.146.6 remote-as 100

no auto-summary

=======================================================

R2

router bgp 100

no synchronization

bgp log-neighbor-changes

network 155.1.2.2 mask 255.255.255.255

neighbor 155.1.23.3 remote-as 100

neighbor 155.1.45.5 remote-as 100

neighbor 155.1.146.1 remote-as 100

neighbor 155.1.146.4 remote-as 100

neighbor 155.1.146.6 remote-as 100

no auto-summary

Highlighted

you have /32 advertised under bgp network statement..

network 155.1.1.1 mask 255.255.255.255

but the routing table entry is /24  or some other mask (not really sure)

150.1.0.0/24 is subnetted, 1 subnets

C       150.1.1.0 is directly connected, Loopback0

the network statement should have an exact match on the routing table (via igp or static or connected routes) in order to advertise...

to correct this, either change loopback to /32 or

change the mask on the network command to /24...it's your choice

Regards Vinayak

View solution in original post

Highlighted

Ya I tried same thing and it does work.

Thanks everyone.