Pathping

Article
09/11/2009

Provides information about network latency and network loss at intermediate hops between a source and destination. Pathping sends multiple Echo Request messages to each router between a source and destination over a period of time and then computes results based on the packets returned from each router. Because pathping displays the degree of packet loss at any given router or link, you can determine which routers or subnets might be having network problems. Pathping performs the equivalent of the tracert command by identifying which routers are on the path. It then sends pings periodically to all of the routers over a specified time period and computes statistics based on the number returned from each. Used without parameters, pathping displays help.

Syntax

pathping [-n] [-h MaximumHops] [-g HostList] [-p Period] [-q NumQueries [-w Timeout] [-T] [-R] [TargetName]

Parameters

-n : Prevents pathping from attempting to resolve the IP addresses of intermediate routers to their names. This might expedite the display of pathping results.

-h MaximumHops : Specifies the maximum number of hops in the path to search for the target (destination). The default is 30 hops.

-g HostList : Specifies that the Echo Request messages use the Loose Source Route option in the IP header with the set of intermediate destinations specified in HostList. With loose source routing, successive intermediate destinations can be separated by one or multiple routers. The maximum number of addresses or names in the host list is 9. The HostList is a series of IP addresses (in dotted decimal notation) separated by spaces.

-p Period : Specifies the number of milliseconds to wait between consecutive pings. The default is 250 milliseconds (1/4 second).

-q NumQueries : Specifies the number of Echo Request messages sent to each router in the path. The default is 100 queries.

-w Timeout : Specifies the number of milliseconds to wait for each reply. The default is 3000 milliseconds (3 seconds).

-T : Attaches a layer-2 priority tag (for example, 802.1p) to the Echo Request messages that it sends to each of the network devices along the route. This helps to identify network devices that do not have layer-2 priority capability. This switch is used to test for Quality of Service (QoS) connectivity.

-R : Determines whether each network device along the route supports the Resource Reservation Protocol (RSVP), which allows the host computer to reserve a specified amount of bandwidth for a data stream. This switch is used to test for Quality of Service (QoS) connectivity.

TargetName : Specifies the destination, which is identified either by IP address or host name.

/? : Displays help at the command prompt.

Remarks

Pathping parameters are case-sensitive.
To avoid network congestion, pings should be sent at a sufficiently slow pace.
To minimize the effects of burst losses, do not send pings too frequently.
When using the -p parameter, pings are sent individually to each intermediate hop. Because of this, the interval between two pings sent to the same hop is period multiplied by the number of hops.
When using the -w parameter, multiple pings can be sent in parallel. Because of this, the amount of time specified in the Timeout parameter is not bounded by the amount of time specified in the Period parameter for waiting between pings.
Using the -T parameter

Enabling layer-2 priority on the host computer allows packets to be sent with a layer-2 priority tag, which can be used by layer-2 devices to assign a priority to the packet. Legacy devices that do not recognize layer-2 priority will discard these packets, since they appear to be malformed. This parameter helps identify network computer that are discarding these packets.
Using the -R parameter

An RSVP reservation message for a nonexistent session is sent to each network device on the route. If the device does not support RSVP, it returns an Internet Control Message Protocol (ICMP) Destination Unreachable-Protocol Unreachable message. If the device does support RSVP, it returns an RSVP Reservation Error message. Some devices might not return either of these messages. If this occurs, a time-out message is displayed.
This command is available only if the Internet Protocol (TCP/IP) protocol is installed as a component in the properties of a network adapter in Network Connections

Examples

The following example shows pathping command output:

D:\>pathping -n corp1
Tracing route to corp1 [10.54.1.196]
over a maximum of 30 hops:
  0  172.16.87.35
  1  172.16.87.218
  2  192.168.52.1
  3  192.168.80.1
  4  10.54.247.14
  5  10.54.1.196
Computing statistics for 125 seconds...
            Source to Here   This Node/Link
Hop  RTT    Lost/Sent = Pct  Lost/Sent = Pct  Address
  0                                           172.16.87.35
                                0/ 100 =  0%   |
  1   41ms     0/ 100 =  0%     0/ 100 =  0%  172.16.87.218
                               13/ 100 = 13%   |
  2   22ms    16/ 100 = 16%     3/ 100 =  3%  192.168.52.1
                                0/ 100 =  0%   |
  3   24ms    13/ 100 = 13%     0/ 100 =  0%  192.168.80.1
                                0/ 100 =  0%   |
  4   21ms    14/ 100 = 14%     1/ 100 =  1%  10.54.247.14
                                0/ 100 =  0%   |
  5   24ms    13/ 100 = 13%     0/ 100 =  0%  10.54.1.196
Trace complete.

When pathping is run, the first results list the path. This is the same path that is shown using the tracert command. Next, a busy message is displayed for approximately 90 seconds (the time varies by hop count). During this time, information is gathered from all routers previously listed and from the links between them. At the end of this period, the test results are displayed.

In the sample report above, the This Node/Link, Lost/Sent = Pct and Address columns show that the link between 172.16.87.218 and 192.168.52.1 is dropping 13 percent of the packets. The routers at hops 2 and 4 also are dropping packets addressed to them, but this loss does not affect their ability to forward traffic that is not addressed to them.

The loss rates displayed for the links, identified as a vertical bar (|) in the Address column, indicate link congestion that is causing the loss of packets that are being forwarded on the path. The loss rates displayed for routers (identified by their IP addresses) indicate that these routers might be overloaded.

Formatting legend

Format	Meaning
Italic	Information that the user must supply
Bold	Elements that the user must type exactly as shown
Ellipsis (...)	Parameter that can be repeated several times in a command line
Between brackets ([])	Optional items
Between braces ({}); choices separated by pipe (\|). Example: {even\|odd}	Set of choices from which the user must choose only one
Courier font	Code or program output

Tracert

Command-line reference A-Z

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