Network response times

Troubleshooting a poor network response time can be difficult, but there are certain quick tests you can perform.

One clear indicator of a network issue is when you find that users in one location have good performance, and users in another location have poor performance. That tells you that the server and application are fine. Assuming that browser settings are identical, the only meaningful difference is the network.

Ping times

The coarsest measure of network response time is a ping. A ping measures the total time for a packet to make it from the source machine to the target and back again.

To perform a ping in Windows, bring up a command window (DOS prompt) and type:

ping -t <yourinstancename>.service-now.com

Look for a time under 100 ms if you are in the U.S., or 150 ms if you are in Europe or Asia. In practice, anything less than 250 ms is not of concern as it is not generally a major component in your perceived response time.

Traceroute

If you are seeing slow ping times, you can run a traceroute. Some networks refuse to forward ICMP, and your traceroute request may not work. If it does work, it is a great tool for identifying network bottlenecks. To run a traceroute on Windows, bring up a command window and run the following command.

tracert <yourinstancename>.service-now.com

Sample output:

 C:\dev\mysql5\bin>tracert mycompany.service-now.com
 Tracing route to mycompany.service-now.com [70.87.98.130]
 over a maximum of 30 hops:
 1     1 ms     1 ms     1 ms  12.192.116.193
 2     4 ms     4 ms     4 ms  12.116.227.37
 3    32 ms    32 ms    32 ms  gbr1-p90.sd2ca.ip.att.net [12.123.145.178]
 4    33 ms    33 ms    33 ms  tbr1-p013503.phmaz.ip.att.net [12.122.2.142]
 5    34 ms    33 ms    33 ms  tbr2-cl1521.phmaz.ip.att.net [12.122.10.194]
 6    32 ms    33 ms    33 ms  tbr2-cl1592.dlstx.ip.att.net [12.122.10.81]
 7    31 ms    50 ms    31 ms  gar1-p370.dlrtx.ip.att.net [12.123.16.173]
 8    31 ms    31 ms    31 ms  12.119.136.14
 9    31 ms    31 ms    31 ms  te9-1.dsr02.dllstx3.theplanet.com [70.87.253.22]
10    37 ms    37 ms    37 ms  vl41.dsr01.dllstx4.theplanet.com [70.85.127.83]
11    31 ms    37 ms    31 ms  gi1-0-1.car16.dllstx4.theplanet.com [67.18.116.67]
12    32 ms    32 ms    32 ms  70.87.98.130
Trace complete.

Each line in the traceroute represents a network step between the source machine and the destination machine. In the sample traceroute, there were a total of 12 steps required to get the network traffic from the laptop to <yourinstancename>.service-now.com.

• The left column is the step number.
• The next three columns are latency estimates, performed three times to give an average.
• The last column is the machine you are hopping to.

For example, from rows #1 and #2 above, you can tell:

 1     1 ms     1 ms     1 ms  12.192.116.193
 2     4 ms     4 ms     4 ms  12.116.227.37

At the end of row 1, it was at 12.192.116.193. It then took 4 ms (on average) to get to 12.116.227.37.

Generally, with a traceroute, you are looking for individual steps that take a long time, like 500 ms for a particular hop. You are also looking for steps that show an asterisk (*) instead of a step time, for example:

 1     100 ms   *        500ms  12.192.116.193

The asterisk indicates that a particular packet failed to arrive, which can indicate network problems on that particular hop. You also see an asterisk if that particular router is set to not forward ICMP. This outcome is potentially a false alarm if all three latency times for a step are asterisks.