Step 2: Check BGP Sessions

Purpose

Display summary information about BGP and its neighbors to determine if routes are received from peers in the autonomous system (AS). When a BGP session is established, the peers are exchanging update messages.

Action

To check that BGP sessions are up, enter the following JUNOS CLI operational mode command from the ingress router:

user@host> show bgp summary

Sample Output 1

user@R1> show bgp summary 

Groups: 1 Peers: 6 Down peers: 1

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 1          1          0          0          0          0

Peer              AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Damped...

10.0.0.2        65432      11257      11259       0       0 3d 21:49:57 0/0/0                0/0/0

10.0.0.3        65432      11257      11259       0       0 3d 21:49:57 0/0/0                0/0/0

10.0.0.4        65432      11257      11259       0       0 3d 21:49:57 0/0/0                0/0/0

10.0.0.5        65432      11257      11260       0       0 3d 21:49:57 0/0/0                0/0/0

10.0.0.6        65432          4       4572       0       1 3d 21:46:59 Active

10.1.36.2       65432      11252      11257       0       0 3d 21:46:49 1/1/0                0/0/0

Sample Output 2

user@R1> show bgp summary 

Groups: 1 Peers: 5 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 1          1          0          0          0          0

Peer              AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State|#Active/Received/Damped...

10.0.0.2        65432         64         68       0       0       32:18 0/0/0                0/0/0

10.0.0.3        65432         64         67       0       0       32:02 0/0/0                0/0/0

10.0.0.4        65432         64         67       0       0       32:10 0/0/0                0/0/0

10.0.0.5        65432         64         67       0       0       32:14 0/0/0                0/0/0

10.0.0.6        65432         38         39       0       1       18:02 1/1/0                0/0/0

What It Means

Sample Output 1 shows that one peer (egress router 10.0.0.6 ) is not established, as indicated by the Down Peers: 1 field. The last column (State|#Active/Received/Damped) shows that peer 10.0.0.6 is active, indicating that is it not established. All other peers are established as indicated by the number of active, received, and damped routes. For example, 0/0/0 for peer 10.0.0.2 indicates that no BGP routes were active or received in the routing table, and no BGP routes were damped; 1/1/0 for peer 10.1.36.2 indicates that one BGP route was active and received in the routing table, and no BGP routes were damped.

If the output of the show bgp summary command of an ingress router shows that a neighbor is down, check the BGP configuration. For information on checking the BGP configuration, see Verify the BGP Configuration.

Sample Output 2 shows output from ingress router R1 after the BGP configurations on R1 and R6 were corrected in Take Appropriate Action. All BGP peers are established and one route is active and received. No BGP routes were damped.

If the output of the show bgp summary command shows that a neighbor is up but packets are not being forwarded, check for received routes from the egress router. For information on checking the egress router for received routes, see Verify Received BGP Routes.