05-20-2007 11:20 PM - edited 03-05-2019 04:11 PM
Hi,
When i doing the BGP home lab, i came to notice that when iam establishing the BGP session between the two private AS which comes under a single public AS
It is forming the adjacency without giving the command #bgp confederation peers (Private AS number)
The one of the router is running of Version 12.2(5)and other router router is 12.2(8)
I dont know why its happening and i tried of shutdown the interface and made the interface UP, same think is happening
can u help me know abt the issue,other think when i try to establish the bgp session between the One public AS to other Privte AS (Which comes under a Public As)without giving the command # bgp conferderation identifier (Public AS)
Then it showing me the NOTIFICATION ERROR MSG
So Why not the above think is not happening
Thanks in advance
Vinoth
05-21-2007 12:18 AM
Hi,
I belive that you have to specify both
confederation identifier and every peer you have in you condederation to make this work:
router bgp 2120
bgp confederation identifier 500
bgp confederation peers 6001 6003
neighbor 10.70.70.1 remote-as 6002
neighbor 172.16.232.57 remote-as 6001
neighbor 172.16.232.56 remote-as 6003
neighbor 10.99.99.2 remote-as 700
Regards,
Bjornarsb
05-21-2007 01:45 AM
Thanks for information,
As 65510 R1----------R2 AS 65520
---------------------------------------------Both R1 and R2 comes under Public AS of 20
What i want to know is whether the TCP connection will establish without giving the command as
R1 # BGP Conferderation peer 65520
and in
R2 # BGP Conferderation peers 65510
Regards,
vinoth
05-21-2007 03:32 AM
Hi, vinoth
Without the bgp confederation peer command, both routers will see each other as a true EBGP peer. R1 will send an open message with AS=20 to R2 and expect to recevie an open message from R2 with AS=65520.
R2 do the same thing.(send an open message with AS=20 and expect to receive an open message with AS=65510). And the result is a wrong-AS issue. Theorectically, the BGP session cannot be established.
And why did your routers can establsh the session successfully? I don't know. Wait the expert to answer you.(Harold, where are you?) Before that, it's a good idea to issue the debug ip bgp command on your routers and see what messages are brought to you.
HTH
SSLIN
05-21-2007 05:14 AM
SSLIN,
You are correct the session should not come up given the above scenario.
Vinoth,
Can you provide the full configurations from both R1 and R2 that led to that mysterious behavior.
Regards,
05-21-2007 09:44 PM
20.0.0.1/8 .2
R2 ----------------- R3
As|65510 As 65520
-----|------------------------------
| Public As 20
|
|10.0.0.1/8
R1
Public As 10
R1#Router bgp 10
#neighbour 10.0.0.2 remote-as 65510
#network 10.0.0.0
R2#router bgp 65510
#neighbour 20.0.0.2 remote-as 65520
#neighbour 10.0.0.1 remote-as 10
#bgp conferderation identifier 10
R3#router bgp 65520
#neighbour 20.0.0.1 remote-as 65510
This what i have done in my home lab and i found that the adjacency is formed between the routers
can u suggest me were is the route cause for this issue
Note : R2 is running on version 12.2 (5)
R3 is running on version 12.2 (8)
Thanks in advance,
vinoth
05-22-2007 03:27 AM
Hi, Vinoth
I try your config and the result is the same.
R2's debugging message
received from neighbor 20.0.0.2 2/2 (peer in wrong AS) 2 bytes 0014
R3's debugging message
BGP: 20.0.0.1 bad OPEN, remote AS is 20, expected 65510
show ip bgp summary on R2
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
20.0.0.2 4 65520 8 8 0 0 0 never Active
show ip bgp summary on R3
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
20.0.0.1 4 65510 8 8 0 0 0 never Active
Would you please post your output of "debug ip bgp" and "show ip bgp summary"?
SSLIN
05-22-2007 04:50 AM
This is not normal. I tried with 12.2(10) and the session didn't come up.
You are probably running in to some older bug. I would suggest you try with more recent code, in which case you should see that the session won't form.
Hope this helps,
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