Step 1: Check That BGP Sessions Are Up

Action

To check that all IBGP and EBGP sessions are properly established, enter the following JUNOS CLI operational mode command:

user@host> show bgp summary

Sample Output 1

The following sample output from R2 shows four peers that are not established:

user@R2> show bgp summary 

Groups: 2 Peers: 4 Down peers: 1

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 6          4          0          0          0          0

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

10.0.0.3        65002         86         90       0       2       42:54 0/0/0                0/0/0

10.0.0.4        65002         90         91       0       1       42:54 0/2/0                0/0/0

10.0.0.6        65002         87         90       0       3           3 Active

10.1.12.1       65001         89         89       0       1       42:54 4/4/0                0/0/0

Sample Output 2

The following sample output shows that all peers are established:

user@R2> show bgp summary 

Groups: 2 Peers: 4 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 6          4          0          0          0          0

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

10.0.0.3        65002      54440      54457       0       1     2w4d21h 0/0/0                0/0/0

10.0.0.4        65002      51505      51507       0       0     2w3d21h 0/2/0                0/0/0

10.0.0.6        65002      14066      14070       0       1 4d 21:15:14 0/0/0                0/0/0

10.1.12.1       65001      88580      88587       0       0     4w2d18h 4/4/0                0/0/0

user@R3> show bgp summary 

Groups: 1 Peers: 3 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 6          4          0          0          0          0

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

10.0.0.2        65002      54476      54460       0       1        7:17 4/4/0                0/0/0

10.0.0.4        65002      51527      51511       0       0     2w3d21h 0/2/0                0/0/0

10.0.0.6        65002      54459      54459       0       0     2w4d21h 0/0/0                0/0/0 

user@R4> show bgp summary 

Groups: 2 Peers: 4 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 8          4          0          0          0          0

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

10.0.0.2        65002      51530      51532       0       1         8:59 2/4/0                0/0/0

10.0.0.3        65002      51512      51531       0       0     2w3d21h 0/0/0                0/0/0

10.0.0.6        65002      51515      51530       0       0     2w3d21h 0/0/0                0/0/0

10.1.45.2       65001      51520      51530       0       0      2w3d21h 2/4/0                0/0/0

user@R6> show bgp summary 

Groups: 1 Peers: 3 Down peers: 0

Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending

inet.0                 6          4          0          0          0          0

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

10.0.0.2        65002      88610      88587       0       2       10:30 2/4/0                0/0/0

10.0.0.3        65002      54464      54468       0       1     2w4d22h 0/0/0                0/0/0

10.0.0.4        65002      51532      51520       0       0     2w3d21h 2/2/0 

What It Means

Sample output 1 shows a peer that is not established, while sample output 2 shows that all IBGP and EBGP sessions shown in the network diagram in Figure 15 are established.

Sample output 1 shows one peer (10.0.0.6) is not established, as indicated by the Down Peers: 1 field. The State|#Active/Received/Damped column also displays Active, indicating that the peer is in the Active state and not yet established.

The State|#Active/Received/Damped) column is a dual purpose field, as indicated by the pipe (|). When a peer is not established (as in our example), the field indicates the state of the peering session, such as active, connect, or idle. When the peer is in the Established state, the field displays the number of active, received, or damped routes received from the neighbor. For example, peer 10.0.0.6 is an example of the last column displaying the Active state, and peer 10.1.12.1 is an example of the last column showing the number of active, received, and damped routes (4/4/0). For more detailed information on the show bgp summary command, see the JUNOS Routing Protocols and Policies Command Reference.

If the BGP neighbor session is not established, use the ping and show route commands to verify network connectivity to the BGP neighbor. Also, use the show log messages command to look for any errors pertaining to the peer in question.

Sample output 2 shows that all IBGP and EBGP sessions shown in the network diagram in Figure 15 are established, as indicated by the Down Peers: 0 field and the last column that shows the number of routes.

Following is a description of the output for all established BGP peers, R2, R3, R4, and R6.

The route information for border router R2 shows the following:

• 0/0/0 for internal peers 10.0.0.3 and 10.0.0.6, indicating that no BGP routes are received or active in the routing table from those peers. No BGP routes are damped.
• 0/2/0 for internal peer 10.0.0.4, indicating that two received BGP routes are not active in the routing table. No BGP routes are damped.
• 4/4/0 for external peer 10.1.12.1, indicating that four received BGP routes are active in the routing table. No BGP routes are damped.

The route information for internal router R3 shows the following:

• 0/0/0 for internal peer 10.0.0.6, indicating that no BGP routes are received or active in the routing table from that peer. No BGP routes are damped.
• 0/2/0 for internal peer 10.0.0.4, indicating that two received BGP routes are not active in the routing table. No BGP routes are damped.
• 4/4/0 for internal peer 10.0.0.2, indicating that four received BGP routes are active in the routing table. No BGP routes are damped.

The route information for border router R4 shows the following:

• 0/0/0 for internal peers 10.0.0.3 and 10.0.0.6, indicating that no BGP routes are received or active in the routing table from those peers. No BGP routes are damped.
• 2/4/0 for internal peer 10.0.0.2 and external peer 10.1.45.1, indicating that two BGP routes are active in the routing table, but four are received. No BGP routes are damped.

The route information for internal router R6 shows the following:

• 0/0/0 for internal peer 10.0.0.3, indicating that no BGP routes are received or active in the routing table from that peer. No BGP routes are damped.
• 2/4/0 for internal peers 10.0.0.2,and 10.0.0.4, indicating that of the four received BGP routes, two are active in the routing table. No BGP routes are damped.

Other information in the sample output includes the following:

• Number of configured BGP groups: R2 has two groups configured (internal and toR1), and R4 also has two BGP groups configured (internal and toR5).
• Number of BGP peers to which the router is linked: R2 and R4 have four (one EBGP and three IBGP), and R3 and R6 have three IBGP. One peer is down (R6) in sample output 1.
• The name of the routing table storing the BGP routes, all routers are using inet.0.
• The total number of BGP paths, for example, R4 has a total of eight BGP paths from all of its peers.
• The number of active BGP routes, for example, R4 has a total of four active BGP routes from all of its peers.
• The second column of values (0/0/0) in the State|#Active/Received/Damped field indicates the number of multiprotocol BGP (MBGP) routes. All routers do not have any received, active, or damped MBGP routes.