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Beginner

Bgp neighborship question

Hi.

one question.

why  bgp neighborship doesn"t establish when no dynamic routing protocol is enabled?

 

there four router.

A--------B-------C-------D

they all can ping. 

No dynamic routing

static routing only enabled.

 

Configured bgp as 100 with A and D but bgp neighborshi didn"t establish.

am i missing something??

 

11 REPLIES 11
Hall of Fame Guru

As long as the IP address of

As long as the IP address of the peer is reachable it should be able to establish a peering.

If this was EBGP you may need to add extra configuration because it expects a direct connection but it is IBGP because A and D are in the same AS so it shouldn't matter.

Can you provide more details ?

Jon

Beginner

It was ibgp. Config was like 

It was ibgp. Config was like 

//A//

router bgp 10

nei 1.1.34.4(D address) remote-as 10

//D//

router bgp 10

nei 1.1.12.1(A address) remote-as 10

 

they can ping each other. But state, stUck in active

Hall of Fame Guru

Should work as long as they

Should work as long as they all have routes to each other and it sounds like they do.

Did you try debugging BGP to see what is actually happening ?

Jon

Beginner

From A side :R1#ping 1.1.34

From A side :

R1#ping 1.1.34.4

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.34.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 80/127/164 ms

R1#show ip route


     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.12.0 is directly connected, FastEthernet0/0
S*   0.0.0.0/0 [1/0] via 1.1.12.2
R1#ping 1.1.34.4

 

R1#sh ip bgp summary
BGP router identifier 1.1.12.1, local AS number 10
BGP table version is 1, main routing table version 1

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
1.1.34.4        4    10       0       0        0    0    0 never    Active
 

 

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

From D side :

R4#sh ip bgp summary
BGP router identifier 1.1.34.4, local AS number 10
BGP table version is 1, main routing table version 1

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
1.1.12.1        4    10       0       0        0    0    0 never    Active
R4#

 

there's no special log. i tested in my GNS3 and i can open 179 both side by using telnet

weird thing is that when i enabled ospf for all of this topology, BGP neighborship was established.  that's why i asked this question. 

/////////////////////////////////////

router ospf 1

net 0.0.0.0 0.0.0.0 a 0

////////////////////////////////////

Hall of Fame Guru

If you send me your

If you send me your configurations I can lab it up for you and see if I get the same issue.

What might be worth testing first though is to take a copy of all the routing tables then remove the statics and enable OSPF and compare.

It might show you if some routes are actually missing.

Jon

Beginner

I tested and found out

I tested and found out something. 

removed OSPF

A and D, they have default route like 0.0.0.0 0.0.0.0

so i added static route in A /* ip route 1.1.34.4 255.255.255.255 */

after that, BGP established. what's the issue ?? why can't run with default route? is this only GNS3 problem?

 

Hall of Fame Guru

Well you learn something new

Well you learn something new every day :-)

Just did a quick search and apparently BGP will not use a default route when trying to establish a peering.

More specifically the BGP peer that initiates the connection cannot use a default route whereas the peer that receives the request can use a default route to reply to the sender.

Didn't know that, or if I did I have forgotten it.

Jon

Beginner

Thank you : ) you save me : )

Thank you : ) you save me : )

VIP Advisor

HelloI didn't know that

Hello

I didn't know that either - I guess I have read about it and not digested that little nugget of information

cheer Jon

res
Paul



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
VIP Advisor

Hellodoes an extended ping

Hello

does an extended ping work and if versa?

ping 1.1.34.4 source 1.1.12.1  

also do do you have any acls denying tcp port 179

 

laastly if the peer isnt directly connected you need to use update source command

 

Res

paul

 

 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future
Highlighted
Beginner

they can ping with source

they can ping with source command and there's no ACL

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