Confirm "Active" meaning in BGP

[news2010a]

Hi,

Can I infer that based on the below the "Active" means that I have successful layer 3 connectivity to my BGP remote peer.

That is about it, correct?

gw1#show ip bgp summ
BGP router identifier 10.1.1.47, local AS number 64
BGP table version is 1, main routing table version 1

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.1.5.70   4 64       0       0        0    0    0 never    Active

[Giuseppe Larosa]

Hello Marlon,

I would say that this is not good sign:

the BGP session is configured on your side and the BGP neighbor state machine for this neighbor has been started.

but the configuration may be missing on the other side for example or there is a problem of TTL if it is an eBGP session

the right state to look for is established in sh ip bgp neigh.

in sh ip bgp sum you should see the number of rx prefixes (including 0 special case)

Edit:

this is an iBGP session so I would look at the other side

also check if you have used the right neigh x.x.x.x update-source command if you want to use loopback addresses

to test ip connectivity you can use extended ping to BGP peer using the right source

Hope to help

Giuseppe

[news2010a]

But do you know if I can say for sure that the "Active" means layer 3 connectivity is OK?
I did not find such conclusion in the documentation.

For example, I attempted to establish a session with a fake, inexistent IP and I got state = Idle.

[Reza Sharifi]

Layer-3 connectivity has be ok before you can establish a BGP peer.  If for example you are connecting 2 routers together via IBGP using the loopback interfaces you should be able to ping each loopback interface before you even configure BGP. The same applies to EBGP.

As for BGP states take a look at the RFC:

http://www.freesoft.org/CIE/RFC/1771/31.htm

HTH

Reza

[Gaurav Madan]

I know that this is a very old post ; but just wanted to add a few things . The BGP states are :

1) Idle 2) Connect 3) Active 4) open sent 5) open confirm 6) established

State 1-> 3 deal with TCP only

State 4->6 deal with BGP

By state Active ; we mean that there is still a issue in routerA establishing TCP session to router B OR there is a issue in router B establishing TCP session to router A OR both

idle means router A attempted a TCP session on port 179 to router B

connect means router B also attempted the same to router A now

If either of these 2 are not successful ; router state machine falls to ACTIVE state .

I hope this makes better sense now

[bigraou147]

Hi,

This state means you didn't put the ''neighbor x.x.x.x update-source y.y.y.y

If this session is established on the loopback address, you have to put it at the place of y.y.y.y

[fly]

I think this is not right.

connect means router A send TCP syn to router b 179

if router A can't get response from router b, router A think router B bgp in connect state, So router A will keep router B bgp peer in connect state，

if router A meet some TCP problem,or receive some information indicate TCP connection problem, router A will transfer router B bgp peer state to Active state.

and create new tcp connection to Router B, if not get response ,when timeout, router A will transfer router bgp B peer state back to connect state

[milan.kulik · Accepted solution]

No,

Active means the router is trying to establish a BGP session, nothing more.

It does NOT mean TCP connectivity to the neighbor is OK at the moment.

Here is an example from my lab:

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
10.90.1.4       4 65015    2508    2502      170    0    0 1d17h         163
172.30.155.20   4   111       0       0        0    0    0 never    Active
PE1#ping 172.30.155.20

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.30.155.20, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
PE1#

172.30.155.20 is a fake neighbor, not alive, just configured in my PE1 configuration.

HTH,

Milan

[Cherrycuevo]

Hi

I have the same problem, status is just Active and not established however I'am able to ping the peering IP, what does it mean? thanks

[moorthy2007]

hi anyone help

i have configured ibgp to directly conncted interface from f0/0 1.1.1.1 to f0/0 1.1.1.2

R2

router bgp 100
bgp log-neighbor-changes
neighbor 1.1.1.1 remote-as 100

R1

router bgp 100
bgp log-neighbor-changes
neighbor 1.1.1.2 remote-as 100

BUT STILL IT IS IN ACTIVE

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
1.1.1.1 4 100 0 0 0 0 0 never Active

[Harold Ritter]

Are you able to ping from R1 to R2 and vice versa? Do you have any ACL that could prevent the TCP session from getting established? The next step would be to do a "debug ip bgp" on both R1 and R2 to see what is going on.

Regards,

[Giuseppe Larosa · Accepted solution]

Hello Marlon,

from BGP state Active we can only guess that local node knows how to send a BGP packet to that specific BGP peer address because BGP state machine has moved to Active state (a BGP open message has been sent and will be sent from time to time)

But this does not mean that bidirectional connectivity is fine between BGP endpoints.

Hope to help

Giuseppe

[somphong.p]

I found the configuration be missing on the other side. lol

Thank you very much.

[Tharak Abraham]

Layer 3 should be up in "active".

Its trying to establish the TCP connection.

Identify the source and the destination of your peering !

1.You need to check for the ttl and update source reachability

2.Check for the correct statements and peering source and destination.

[anooshoks]

Dear All,

The BGP active means the local router it' trying to send traffic but not there is response from the neighbor .