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 thattracert
is running. Sopathping
shows you what the network is doing over a period of 325 seconds (by default), andtracert
is showing you what 3 packets per hop on the network are doing.