Juniper Networks J-Series manual Tracing Unicast Routes from the J-Web Interface

Chapter 12: Using Services Router Diagnostic Tools

■The host is not operational.

■There are network connectivity problems between the Services Router and the host.

■The host might be configured to ignore echo requests.

■The host might be configured with a firewall filter that blocks echo requests or echo responses.

■The size of the echo request packet exceeds the MTU of a host along the path.

■The outbound node at the remote endpoint is not configured to handle MPLS packets.

■The remote endpoint's loopback address is not configured to 127.0.0.1.

Tracing Unicast Routes from the J-Web Interface

You can use the traceroute diagnostic tool to display a list of routers between the Services Router and a specified destination host. The output is useful for diagnosing a point of failure in the path from the Services Router to the destination host, and addressing network traffic latency and throughput problems.

The Services Router generates the list of routers by sending a series of ICMP traceroute packets in which the time-to-live (TTL) value in the messages sent to each successive router is incremented by 1. (The TTL value of the first traceroute packet is set to 1.) In this manner, each router along the path to the destination host replies with a Time Exceeded packet from which the source IP address can be obtained.

Alternatively, you can use the CLI traceroute command to generate the list.

This section contains the following topics:

■Using the J-Web Traceroute Tool on page 223

■Traceroute Results and Output Summary on page 225

Using the J-Web Traceroute Tool

To use the traceroute tool:

1.Select Diagnose>Traceroute.

2.Next to Advanced options, click the expand icon (see Figure 23 on page 224).

3.Enter information into the Traceroute page, as described in Table 112 on page 224. The Remote Host field is the only required field.

4.Click Start.

The results of the traceroute operation are displayed in the main pane. If no options are specified, each line of the traceroute display is in the following format:

hop-number host (ip-address)[as-number]time1 time2 time3

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