eBGP host cant Communicate eBGP Host over iBGP mesh

[TangoAlfa]

Hi All,

Refer to the diagram Host-A can communicate Host-B and Host-C can communicate with Host-D but Host-A and Host-B can not communicate with Host-C and D. Where as every where route is available.

NOTE:

From R-3 and 4 I can reach Host-C and D

From R-1 and 2 I can reach Host-A and B

Please refer attached diagram.

[MHM Cisco World]

Remove defualt route from you network are check then other  bgp path are it  show valid best ??

[TangoAlfa]

Hi MHM Thanks for your reply.

But I don't have any default route in this network

[MHM Cisco World]

Can I see

show ip bgp

in R4?

[TangoAlfa]

PFA how ip bgp in R4

[paul driver]

Hello
The most probable cause is

next-hop

reachability within your ibgp network, make sure you have full igp connectivity to all ibgp peer rtrs transit networks  also on each ibgp router to each ibgp peer append the

neighbour next-hop-self command

example:
rtr1-4
router eigrp 100
no auto-summary
network 0.0.0.0 0.0.0.0

router bgp  65000
no auto-summary
neighbour <ibgp peer1> next-hop-self
neighbour <ibgp peer2> next-hop-self
neighbour <ibgp peer3> next-hop-self

[TangoAlfa]

Hi Paul,

Thanks for the reply. I have configure next hop self in R-4 towards all iBGP Peer. But Problem same

[MHM Cisco World]

Not only R4 need

next-hop self

But all ibgp router need that. 

Config

next-hop self

in all and do ping again. 

Thanks 

MHM

[TangoAlfa]

I did the same. but still

R-1#sho running-config | section bgp
router bgp 65000
bgp log-neighbor-changes
neighbor 192.168.2.2 remote-as 65000
neighbor 192.168.2.2 next-hop-self
neighbor 192.168.4.1 remote-as 65000
neighbor 192.168.4.1 next-hop-self
neighbor 192.168.6.1 remote-as 65000
neighbor 192.168.6.1 next-hop-self all
neighbor 192.168.13.1 remote-as 65002
neighbor 192.168.15.1 remote-as 65001

--------------------------------

R-2#sho running-config | sec bgp
router bgp 65000
bgp log-neighbor-changes
neighbor 192.168.2.1 remote-as 65000
neighbor 192.168.2.1 next-hop-self
neighbor 192.168.3.1 remote-as 65000
neighbor 192.168.3.1 next-hop-self
neighbor 192.168.5.1 remote-as 65000
neighbor 192.168.5.1 next-hop-self
neighbor 192.168.12.1 remote-as 65002
neighbor 192.168.14.1 remote-as 65001
R-2#

-----------------------------------

R-3#sho run
R-3#sho running-config | sec bgp
router bgp 65000
bgp log-neighbor-changes
neighbor 192.168.3.2 remote-as 65000
neighbor 192.168.3.2 next-hop-self
neighbor 192.168.6.2 remote-as 65000
neighbor 192.168.6.2 next-hop-self
neighbor 192.168.7.2 remote-as 65000
neighbor 192.168.7.2 next-hop-self
neighbor 192.168.9.1 remote-as 65004
neighbor 192.168.10.1 remote-as 65003
R-3#
R-3#

-----------------------------
R-4#sho running-config | section bgp
router bgp 65000
bgp log-neighbor-changes
neighbor 192.168.4.2 remote-as 65000
neighbor 192.168.4.2 next-hop-self
neighbor 192.168.5.2 remote-as 65000
neighbor 192.168.5.2 next-hop-self
neighbor 192.168.7.1 remote-as 65000
neighbor 192.168.7.1 next-hop-self
neighbor 192.168.8.1 remote-as 65004
neighbor 192.168.11.1 remote-as 65003
R-4#

-----------------------------

[MHM Cisco World]

Clear ip bgp x 

DO this in ibgp router

Check again 

[TangoAlfa]

just Did the same but issue is same.

[MHM Cisco World]

Share

ip bgp

of R4

[paul driver]

Hello
Do you have the routes that you cannot reach in the bgp table, and is the next hop of that bgp route valid or is it stating inaccessible?

sh ip bgp x.x.x.x

[TangoAlfa]

in all router

 #sho ip bgp #sho ip route

is available. Just tell me one thing that shall I advertise all the iBGP directly connected /30 network too?

[TangoAlfa]

Bit surprise. Even I am unable to reach from R-7(eBGP) to R-3(iBGP) other interface. attach snap in detail.