pjhtech ToolsJunos Interface Errors and Optical Power Commands
Check Juniper link state, interface errors, flaps and optical receive power. A practical read-only workflow for MX, with EX and SRX differences.
Read-only command: show interfaces terse
Juniper Junos Command References
Move from a reported symptom to a specific Junos observation. These references separate physical interface state, routing-table selection, routing-protocol adjacencies and forwarding evidence. They also distinguish MX routing examples from EX ELS switching commands where the command families differ.
10 references
Read-only results link to an individual observation command. Other commands on the same page can have different effects.
No matching references. Try a task such as packet capture, route lookup, BGP or interface errors.
How to use these references
For a missing destination, start with the route and routing-instance reference. Then inspect the protocol that should supply the route. BGP, OSPF and IS-IS pages explain what the neighbor state proves and what still needs to be checked. Interface and LACP references help identify the underlying port and bundle condition without clearing counters or bouncing a link.
For a device-location task, combine LLDP, ARP and the appropriate MAC table. For a suspected filter drop, inspect the installed filter and its actual counters rather than assuming every term counts matches.
The configuration reference explains candidate changes, comparisons, confirmed commits and rollback as a separate workflow. Operational inspection and configuration changes are kept apart. Read the page's platform scope before applying an MX example to EX, SRX or Junos OS Evolved.
Junos Route Lookup and VRF Routing Table Commands
Find IPv4 and IPv6 routes in Junos inet.0 and VRF tables. Compare a destination lookup, an exact prefix and the Routing Engine forwarding table.
Read-only command: show route summary
Junos BGP Troubleshooting: Neighbors and Advertised Routes
Troubleshoot Juniper BGP state, received routes and advertised prefixes. Understand what each command proves before resetting a session.
Read-only command: show bgp summary
Junos OSPF Troubleshooting Commands and Neighbor States
Check Junos OSPF neighbors, interface timers, MTU and learned routes. Distinguish normal 2-Way behavior from a failed adjacency.
Read-only command: show ospf neighbor
Junos IS-IS Commands: Adjacencies, Levels and Metrics
Inspect IS-IS neighbors, Level 1 and Level 2 operation, interface metrics and the database on Juniper MX without resetting the protocol.
Read-only command: show isis adjacency
Junos LLDP, ARP and MAC Address Lookup Commands
Trace an endpoint from IP to MAC to switch port. Separate Juniper EX ELS switching commands from MX bridge-domain commands.
Read-only command: show arp no-resolve
Junos Firewall Filter Counters and Packet-Drop Checks
Inspect Junos stateless firewall filters, counters and policers. Verify attachment and compare counter changes without clearing production evidence.
Read-only command: show firewall
Junos Compare, Commit Confirmed and Rollback Reference
Review a Junos candidate, validate syntax and use commit confirmed deliberately. Understand rollback 0 versus rollback 1 before changing a device.
Read-only command: show system commit
Junos LACP Troubleshooting and AE Member Commands
Check Juniper LACP actor and partner state, packet counters and aggregate members. Diagnose a missing link without bouncing the whole bundle.
Read-only command: show interfaces ae0 terse
Junos Logs, NTP and System Health Commands
Collect Juniper logs, current time, NTP peer state and alarms before troubleshooting. Build a reliable incident timeline with read-only commands.
Read-only command: show version