Intermittent high ping/latency problem

isplatencynetworkingping

I have been working with my ISP (which is a WISP, actually Fixed Broadband Wireless) trying to figure out why I intermittently get high latency. The latency is detectable in online games and other streaming applications. If I do a trace route you can see the path though the back-haul network:

Tracing route to google.com [74.125.67.105]
over a maximum of 30 hops:

  1     1 ms     4 ms    <1 ms  192.168.23.1
  2     1 ms     8 ms     9 ms  10.100.100.1
  3     9 ms     9 ms     3 ms  10.7.37.1
  4    15 ms    24 ms    19 ms  10.7.36.1
  5    10 ms    79 ms     9 ms  10.7.31.3
  6    10 ms    39 ms    39 ms  10.10.5.9
  7    19 ms    19 ms    19 ms  10.10.5.5
  8     9 ms    19 ms    19 ms  10.10.5.1
  9   341 ms   237 ms   226 ms  10.250.200.1
 10   249 ms   280 ms   991 ms  <ISP WAN IP>
 11   703 ms   681 ms   401 ms  <ISP WAN IP>
 12   819 ms   628 ms   484 ms  <AT&T IP>    <- Traffic enters AT&T backbone
 13   699 ms   528 ms   290 ms  <AT&T IP>
 14   201 ms   106 ms    52 ms  <AT&T IP>
 15   624 ms   392 ms   436 ms  <AT&T IP>
 16   666 ms     *      252 ms  <AT&T IP>
 17   456 ms   403 ms   581 ms  209.85.254.120
 18   430 ms   339 ms     *     209.85.242.215
 19  1061 ms    56 ms    53 ms  72.14.239.131
 20  3514 ms   734 ms   219 ms  209.85.255.190
 21    49 ms    59 ms    56 ms  74.125.67.105

Which seems to indicate that the problem is the host at 10.250.200.1. However, if I directly ping the host everything seems fine (~10ms round-trip). Pinging subsequent hops after the suspected node gives reasonable round-trip times as well. The high latency can persist for only a few seconds up to a few minutes at a time.

EDIT Yes this is a bad example of a trace showing a definite problem, but after repeated tests there is never latency >100ms before hop 9, that's why I thought it could be a problem.

A pathping during the event produces the following:

        Source to Here   This Node/Link
Hop  RTT    Lost/Sent = Pct  Lost/Sent = Pct  Address
  0                                           192.168.23.129
                                0/ 100 =  0%   |
  1    2ms     0/ 100 =  0%     0/ 100 =  0%  192.168.23.1
                                0/ 100 =  0%   |
  2    3ms     0/ 100 =  0%     0/ 100 =  0%  10.100.100.1
                                0/ 100 =  0%   |
  3   14ms     0/ 100 =  0%     0/ 100 =  0%  10.7.37.1
                                0/ 100 =  0%   |
  4   15ms     0/ 100 =  0%     0/ 100 =  0%  10.7.36.1
                                0/ 100 =  0%   |
  5   19ms     0/ 100 =  0%     0/ 100 =  0%  10.7.31.3
                                0/ 100 =  0%   |
  6   27ms     0/ 100 =  0%     0/ 100 =  0%  10.10.5.9
                                0/ 100 =  0%   | 
  7   28ms     0/ 100 =  0%     0/ 100 =  0%  10.10.5.5
                                0/ 100 =  0%   |
  8  ---     100/ 100 =100%   100/ 100 =100%  10.10.5.1
                                0/ 100 =  0%   |
  9   25ms     0/ 100 =  0%     0/ 100 =  0%  10.250.200.1
                                0/ 100 =  0%   |
 10   24ms     1/ 100 =  1%     1/ 100 =  1%  <ISP WAN IP>
                                0/ 100 =  0%   |
 11   25ms     4/ 100 =  4%     4/ 100 =  4%  <ISP WAN IP>
                                0/ 100 =  0%   |
 12   35ms     0/ 100 =  0%     0/ 100 =  0%  <AT&T IP>
                                0/ 100 =  0%   |
 13  ---     100/ 100 =100%   100/ 100 =100%  <AT&T IP>
                                0/ 100 =  0%   |
 14  ---     100/ 100 =100%   100/ 100 =100%  <AT&T IP>
                                0/ 100 =  0%   |
 15  ---     100/ 100 =100%   100/ 100 =100%  <AT&T IP>
                                0/ 100 =  0%   |
 16   58ms     0/ 100 =  0%     0/ 100 =  0%  <AT&T IP>
                                1/ 100 =  1%   |
 17   59ms     1/ 100 =  1%     0/ 100 =  0%  209.85.254.120
                                0/ 100 =  0%   |
 18   59ms     1/ 100 =  1%     0/ 100 =  0%  209.85.242.215
                                0/ 100 =  0%   |
 19   56ms     1/ 100 =  1%     0/ 100 =  0%  72.14.239.127
                                0/ 100 =  0%   |
 20   60ms     1/ 100 =  1%     0/ 100 =  0%  209.85.255.194
                                0/ 100 =  0%   |
 21   59ms     1/ 100 =  1%     0/ 100 =  0%  74.125.67.105

Why does this latency only show up during a trace-route and not with a normal ping? The lack of performance I see in my application coincides with this.

In other words, while having troubles with my application, if I run a trace at the same time I get the above result while simultaneously pinging the suspect host shows a normal ping.

Best Answer

WISP? Meaning Wireless ISP? If so, there's your likely answer. Wireless is unreliable and you're seeing proof of that.

You can't really fix it because your medium (the atmosphere) is really awful for transmitting data. First because air is a hub instead of a switch so you're sharing it with anybody around you and colliding packets, second because CSMA/CA is slower than CSMA/CD, third because wireless is generally half-duplex instead of full duplex, and fourth because there are orders of magnitude higher interference through the air versus copper. [Microwaves, for example, operate at the same wavelength as 802.11b/g... but the microwave operates at about 500-1000 Watts vs your wireless antenna's 100 milliwatts. Microwaves are shielded, but shielding isn't perfect and microwaves aren't regulated by the FCC so it's not illegal if they cause interference.] Plus the fact that you're going through 10+ hops just to get to the Internet. That can't be helping, particularly if there's any NAT or firewalling going on.

As @dbasnett says, the traceroute ping latency to a given host only indicates the state of the entire network in between the interfaces taken as a whole at that point in time. That's why the response times go down sometimes. They're spiky because the network is unreliable. Your pathping looks good because it is running a large number of queries instead of just 3 that tracert is running. So pathping shows you what the network is doing over a period of 325 seconds (by default), and tracert is showing you what 3 packets per hop on the network are doing.

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