Troubleshooting Ping Host

Problem

Description: You can ping a host to verify that the host can be reached over the network. The output is useful for diagnosing host and network connectivity problems. The J Series device sends a series of ICMP echo (ping) requests to a specified host and receives ICMP echo responses.

Solution

To use the ping host tool:

  1. Select Troubleshoot>Ping Host in the J-Web user interface.
  2. Click the expand icon next to Advanced options.
  3. Enter the information specified in Table 266 to troubleshoot the issue.

    The Remote Host field is the only required field.

  4. Click Start.

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

    bytes bytes from ip-address: icmp_seq=number ttl=number time=time
  5. Click OK to stop the ping operation before it is complete.

Table 266: Ping Host Troubleshooting Options

Field

Function

Action

Remote Host

Identifies the host to ping.

Type the hostname or IP address of the host to ping.

Advanced Options

Don't Resolve Addresses

Determines whether or not to display hostnames of the hops along the path.

  • To suppress the display of the hop hostnames, select the check box.
  • To display the hop hostnames, clear the check box.

Interface

Specifies the interface on which the ping requests are sent.

From the list, select the interface on which ping requests are sent. If you select any, the ping requests are sent on all interfaces.

Count

Specifies the number of ping requests to send.

From the list, select the number of ping requests to send.

Don't Fragment

Specifies the don't fragment (DF) bit in the IP header of the ping request packet.

  • To set the DF bit, select the check box.
  • To clear the DF bit, clear the check box.

Record Route

Sets the record route option in the IP header of the ping request packet. The path of the ping request packet is recorded within the packet and displayed in the main pane.

  • To record and display the path of the packet, select the check box.
  • To suppress the recording and display of the path of the packet, clear the check box.

Type-of-Service

Specifies the type-of-service (ToS) value in the IP header of the ping request packet.

From the list, select the decimal value of the ToS field.

Routing Instance

Specifies the name of the routing instance for the ping attempt.

From the list, select the routing instance name.

Interval

Specifies the interval, in seconds, between the transmission of each ping request.

From the list, select the interval.

Packet Size

Specifies the size of the ping request packet.

Type the size, in bytes, of the packet. The size can be from 0 through 65468. The device adds 8 bytes to the size of the ICMP header.

Source Address

Specifies the source address of the ping request packet.

Type the source IP address.

Time-to-Live

Specifies the time-to-live (TTL) hop count for the ping request packet.

From the list, select the TTL.

Bypass Routing

Determines whether or not ping requests are routed by means of the routing table.

If the routing table is not used, ping requests are sent only to hosts on the interface specified in the Interface box. If the host is not on that interface, ping responses are not sent.

  • To bypass the routing table and send the ping requests to hosts on the specified interface only, select the check box.
  • To route the ping requests using the routing table, clear the check box.
Ping Host Results and Output Summary

bytes bytes from ip-address

  • bytes—Size of ping response packet, which is equal to the value you entered in the Packet Size box, plus 8.
  • ip-address—IP address of destination host that sent the ping response packet.

–

icmp_seq=0

icmp_seq=number

number—Sequence Number field of the ping response packet. You can use this value to match the ping response to the corresponding ping request.

–

ttl=number

number—TTL hop-count value of the ping response packet.

–

time=time

time—Total time between the sending of the ping request packet and the receiving of the ping response packet, in milliseconds. This value is also called round-trip time.

–

number packets transmitted

number—Number of ping requests (probes) sent to host.

–

number packets received

number—Number of ping responses received from host.

–

percentage packet loss

percentage—Number of ping responses divided by the number of ping requests, specified as a percentage.

–

round-trip min/avg/max/stddev = min-time/avg-time/max-time/std-dev ms

  • min-time—Minimum round-trip time (see time=time field in this table).
  • avg-time—Average round-trip time.
  • max-time—Maximum round-trip time.
  • std-dev—Standard deviation of the round-trip times.

–

Output = Packet loss of 100 percent

If the device does not receive ping responses from the destination host (the output shows a packet loss of 100 percent), one of the following explanations might apply:

  • The host is not operational.
  • There are network connectivity problems between the device and the host.
  • The host might be configured to ignore ICMP echo requests.
  • The host might be configured with a firewall filter that blocks ICMP echo requests or ICMP echo responses.
  • The size of the ICMP echo request packet exceeds the MTU of a host along the path.
  • The value you selected in the TTL box was less than the number of hops in the path to the host, in which case the host might reply with an ICMP error message.

For more information about ICMP, see RFC 792, Internet Control Message Protocol.

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Related Documentation

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