Junos BGP Troubleshooting: Neighbors and Advertised Routes

Commands #

These operational commands do not reset the BGP session:

show bgp summary

show bgp neighbor 192.0.2.2

show route receive-protocol bgp 192.0.2.2

show route advertising-protocol bgp 192.0.2.2

show route table inet.0 203.0.113.0/24 exact extensive

Use targeted prefixes and table selectors where your release offers them. The broad received/advertised commands can produce substantial output on transit peers; they are included to show the command family, not to encourage repeated full-table captures.

Understand the three views #

The neighbor output describes the session: current state, previous events and negotiated information. Active is a connection-attempt state, not a healthy established session. A recurring hold-time event is useful evidence, but does not by itself identify whether congestion, packet loss, remote processing or another cause interrupted communication.

The receive-protocol view exposes received attributes for the selected routes shown. Juniper explicitly notes that these attributes do not include changes made by import policy. Do not call this command an unconditional record of every route the peer ever sent. Retention and visibility of rejected routes matter when investigating an absent prefix.

The advertising-protocol view shows routes prepared for that neighbor after the relevant export policy. It is the right place to check local advertisement, but it cannot prove that the remote router accepted or installed the route. Ask the remote operator for the corresponding received and selected views.

A focused troubleshooting workflow #

Record the peer IP, local and remote AS, expected prefix, address family and incident time. First decide whether the fault is session establishment or route exchange. For an established session, follow one prefix from reception to the local routing table and then to the intended outbound neighbor. Compare policy names and communities before proposing a change.

Pitfalls #

Do not clear a working session simply because a route is missing. A reset changes evidence and can interrupt other prefixes. Check whether the prefix is more specific than expected, whether the next hop can be resolved, and whether the investigation is in the correct VRF. Do not equate local route selection with global Internet visibility.

Continue with #

Junos Route Lookup and VRF Routing Table Commands explains exact route lookups; Junos Firewall Filter Counters and Packet-Drop Checks checks filter counters and Junos Logs, NTP and System Health Commands helps correlate logs. CIDR List Comparison helps compare the intended prefix coverage with an exported list; the ports reference provides a quick reminder of BGP's transport port.