The BGP peer relationship fails to be established
If BGP peers can successfully ping each other, there are available routes between BGP peers and link transmission is normal
Run the display acl all command on the two devices to check whether an ACL is configured to filter the packets with the destination port TCP port 179.
View information about BGP peers to check whether the peer and local router IDs conflict. For example, if the IPv4 unicast peer relationship fails to be established, run the display bgp peer command to check whether the peer router ID conflicts with the local router ID. In the following example command output, the local router ID is 126.96.36.199.
Run the display bgp peer command on each device to check whether the displayed peer AS number is the same as the remote AS number.
Run the display current-configuration configuration bgp command to check BGP configurations.
Run the ping command to check whether BGP peers can successfully ping each other.
Check that no ACL is configured to filter the packets with the destination port TCP port 179.
Check that the peer router ID does not conflict with the local router ID.
Check that the peer AS number is configured correctly.
Check whether BGP configurations affect the establishment of the BGP peer relationship.
Follow Troubleshooting Steps then in case of failure contact Enterprise TAC