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Diagnostic Tools Overview

Use the J-Web Diagnose options to diagnose a device. J-Web results are displayed in the browser.

You can also diagnose the device with CLI operational mode commands. CLI command output appears on the screen of your console or management device, or you can filter the output to a file.

This section contains the following topics. To filter output to a file, see Filtering Command Output.

J-Web Diagnostic Tools Overview

The J-Web diagnostic tools consist of the options that appear when you select Troubleshoot and Maintain in the task bar. Table 193 describes the functions of the Diagnose and Manage options.

Table 193: J-Web Interface Diagnose and Manage Options

Option	Function
Troubleshoot Options
Ping Host	Allows you to ping a remote host. You can configure advanced options for the ping operation. For details, see Using the J-Web Ping Host Tool.
Ping MPLS	Allows you to ping an MPLS endpoint using various options. For details, see MPLS Connection Checking.
Traceroute	Allows you to trace a route between the device and a remote host. You can configure advanced options for the traceroute operation. For details, see Tracing Unicast Routes from the J-Web Interface .
Packet Capture	Allows you to capture and analyze router control traffic. For details, see Capturing and Viewing Packets with the J-Web Interface.
Maintain Options
Files	Allows you manage log, temporary, and core files on the device. For details, see Managing Files with the J-Web Interface.
Upgrade	Allows you to upgrade and manage device software packages. For details, see Performing Software Upgrades and Reboots.
Licenses	Displays a summary of the licenses needed and used for each feature that requires a license. Allows you to add licenses. For details, see the JUNOS Software Administration Guide.
Reboot	Allows you to reboot the device at a specified time. For details, see Rebooting or Halting the Device with the J-Web Interface.

CLI Diagnostic Commands Overview

The CLI commands available in operational mode allow you to perform the same monitoring, troubleshooting, and management tasks you can perform with the J-Web interface. Instead of invoking the tools through a graphical interface, you use operational mode commands to perform the tasks.

Because the CLI is a superset of the J-Web interface, you can perform certain tasks only through the CLI. For example, you can use the mtrace command to display trace information about a multicast path from a source to a receiver, which is a feature available only through the CLI.

To view a list of top-level operational mode commands, type a question mark (?) at the command-line prompt.

At the top level of operational mode are the broad groups of CLI diagnostic commands listed in Table 194.

Table 194: CLI Diagnostic Command Summary

Command	Function
Controlling the CLI Environment
set option	Configures the CLI display.
Diagnosis and Troubleshooting
clear	Clears statistics and protocol database information.
mtrace	Traces information about multicast paths from source to receiver. For details, see Tracing Multicast Routes from the CLI.
monitor	Performs real-time debugging of various software components, including the routing protocols and interfaces. For details, see the following sections: Using the monitor interface Command Using the monitor traffic Command Displaying Log and Trace Files from the CLI
ping	Determines the reachability of a remote network host. For details, see Pinging Hosts from the CLI.
ping mpls	Determines the reachability of an MPLS endpoint using various options. For details, see MPLS Connection Checking.
test	Tests the configuration and application of policy filters and AS path regular expressions.
traceroute	Traces the route to a remote network host. For details, see Tracing Unicast Routes from the CLI.
Connecting to Other Network Systems
ssh	Opens secure shell connections. For details, see Using the ssh Command.
telnet	Opens Telnet sessions to other hosts on the network. For details, see Using the telnet Command.
Management
copy	Copies files from one location on the device to another, from the device to a remote system, or from a remote system to the device.
restart option	Restarts the various system processes, including the routing protocol, interface, and SNMP processes.
request	Performs system-level operations, including stopping and rebooting the device and loading software images.
start	Exits the CLI and starts a UNIX shell.
configuration	Enters configuration mode. For details, see the JUNOS Software Administration Guide.
quit	Exits the CLI and returns to the UNIX shell.

MPLS Connection Checking

Use either the J-Web ping MPLS diagnostic tool or the CLI ping mpls command to diagnose the state of label-switched paths (LSPs), Layer 2 and Layer 3 virtual private networks (VPNs), and Layer 2 circuits.

When you use the ping MPLS feature from a J Series device operating as the inbound (ingress) node at the entry point of an LSP or VPN, the router sends probe packets into the LSP or VPN. Based on how the LSP or VPN outbound (egress) node at the remote endpoint of the connection replies to the probes, you can determine the connectivity of the LSP or VPN.

Each probe is an echo request sent to the LSP or VPN exit point as an MPLS packet with a UDP payload. If the outbound node receives the echo request, it checks the contents of the probe and returns a value in the UDP payload of the response packet. If the J Series device receives the response packet, it reports a successful ping response.

Responses that take longer than 2 seconds are identified as failed probes.

Table 195 summarizes the options for using either the J-Web ping MPLS diagnostic tool or the CLI ping mpls command to display information about MPLS connections in VPNs and LSPs.

Table 195: Options for Checking MPLS Connections

J-Web Ping MPLS Tool	ping mpls Command	Purpose	Additional Information
Ping RSVP-signaled LSP	ping mpls rsvp	Checks the operability of an LSP that has been set up by the Resource Reservation Protocol (RSVP). The J Series device pings a particular LSP using the configured LSP name.	When an RSVP-signaled LSP has several paths, the J Series device sends the ping requests on the path that is currently active.
Ping LDP-signaled LSP	ping mpls ldp	Checks the operability of an LSP that has been set up by the Label Distribution Protocol (LDP). The J Series device pings a particular LSP using the forwarding equivalence class (FEC) prefix and length.	When an LDP-signaled LSP has several gateways, the J Series device sends the ping requests through the first gateway. Ping requests sent to LDP-signaled LSPs use only the master routing instance.
Ping LSP to Layer 3 VPN prefix	ping mpls l3vpn	Checks the operability of the connections related to a Layer 3 VPN. The J Series device tests whether a prefix is present in a provider edge (PE) router's VPN routing and forwarding (VRF) table, by means of a Layer 3 VPN destination prefix.	The J Series device does not test the connection between a PE router and a customer edge (CE) router.
Locate LSP using interface name	ping mpls l2vpn interface	Checks the operability of the connections related to a Layer 2 VPN. The J Series device directs outgoing request probes out the specified interface.	For information about interface names, See the interface naming conventions in the JUNOS Software Interfaces and Routing Configuration Guide.
Instance to which this connection belongs	ping mpls l2vpn instance	Checks the operability of the connections related to a Layer 2 VPN. The J series device pings on a combination of the Layer 2 VPN routing instance name, the local site identifier, and the remote site identifier, to test the integrity of the Layer 2 VPN circuit (specified by the identifiers) between the inbound and outbound PE routers.
Locate LSP from interface name	ping mpls l2circuit interface	Checks the operability of the Layer 2 circuit connections. The J Series device directs outgoing request probes out the specified interface.
Locate LSP from virtual circuit information	ping mpls l2circuit virtual-circuit	Checks the operability of the Layer 2 circuit connections. The J Series device pings on a combination of the IPv4 prefix and the virtual circuit identifier on the outbound PE router, testing the integrity of the Layer 2 circuit between the inbound and outbound PE routers.
Ping end point of LSP	ping mpls lsp-end-point	Checks the operability of an LSP endpoint. The J Series device pings an LSP endpoint using either an LDP FEC prefix or an RSVP LSP endpoint address.

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