packet tracer for bgp neighbor establishment test

[mestasew1]

Hello Everyone -

I was practicing bgp neighbor form status with packet tracer, and I shut the peer interface after they established to with the peer.

However the sh ip bgp neighbors output still shows established neighbor as 1. I am using a  version 8.2.2

I also noticed the packet tracer does not support enabling and disabling the ip4-unicast address family feature.

[Flavio Miranda]

@mestasew1 

 You can attach you PT file here, just zip it first. At least show your topology or the device config in order to be easier to help.

Keep in mind that PacketTracer is a very limited network simulator and not everything will work as intended nor will be like real devices

[mestasew1]

@Flavio Miranda  -

thanks for your response. the topology is simple two neighboring routers connecting . I think the issue could be with the packet tracer limitation. After I reloaded the router the connection state still showed Established while the connection establised number indicating 0. see below output for info

### output when peer link is UP/UP

Address tracking is enabled, the RIB does have a route to 10.12.1.2
Connections established 1; dropped 0
Last reset never
Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Connection is ECN Disabled, Minimum incoming TTL 0, Outgoing TTL 1
Local host: 10.12.1.1, Local port: 179

### output after peer link shut ( even though the cnnection established shows 0, the connection state is showing establised (ESTAB)

Connections established 0; dropped 0
Last reset never
Transport(tcp) path-mtu-discovery is enabled
Connection state is ESTAB, I/O status: 1, unread input bytes: 0
Connection is ECN Disabled, Minimum incoming TTL 0, Outgoing TTL 1
Connection tableid (VRF): 0

[Flavio Miranda]

Yes, we need to consider the PT limitations but also keep in mind that BGP is a TCP connection and therefore have a timeout period. Even real world we can see situation where the BGP status does not replect the reality immediatly.

[mestasew1]

I think this one is completely  the PT limitation and is also inconsistence output above. Even though BGP uses TCP , after hold timer expires , the adjacency state expected to show the actual status. May be resetting the bgp process would  speed up...but not applicable on PT.

PT has improved a lot and added various advanced features (like WLC console) in my ages but might be missing some details or planned only to provide only basics for bgp.

Appreciate your response.

[habtemariamzebene6612]

On real devices or GNS3, you can use the command 'clear ip bgp { * | address | peer-group-name} [soft [in | out]]'. However, I believe PT (Packet Tracer) does not support this command