routes at my WISP

I continue to be baffled by my WISP’s networking. Last few days I’ve had frustrating small outages, like 1-2 minutes at a time. But only during working hours. Support told me they were doing “some maintenance that might cause that” one of the days. I fear they think even an occasional 2 minute outage while they reboot equipment is OK, but happening 5+ times a day is getting really old. I do have some sympathy for them though. It’s a fixed wireless network, my house is connected via at least 2 radio relays at other customers’ houses before reaching a wired network. That’s gotta be hard to manage.

Anyway, I realize part of my confusion now is that traceroute is lying to me. Here’s an mtr report after running about 25 minutes.

                                       Packets               Pings
 Host                                Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. OpenWrt.lan                       0.0%  1606    0.4   0.3   0.3   0.5   0.0
 2. sbbgateway.lan                    2.6%  1606    2.2   2.3   1.6  24.6   2.0
 3.                     0.0%  1605   35.7  39.6  16.0 136.5  15.0
 4.                    0.0%  1605   33.3  37.5  14.4 139.4  14.9
 5.                    0.0%  1605   46.1  39.7  17.2 142.3  15.5
 6.                     0.0%  1605   29.0  36.9  18.0 128.5  15.1
 7.                   0.0%  1605   37.8  39.0  17.5 145.9  15.3
 8.            0.0%  1605   39.1  51.3  28.0 176.6  14.3
 9.         0.0%  1605   57.3  51.2  27.4 128.1  15.7
10.                     0.0%  1605  104.7  47.6  28.2 155.5  16.3
11.                    0.0%  1605   57.0  49.5  27.5 142.6  15.9
12.                    0.0%  1605   55.2  50.6  28.3 146.1  15.8
13.    0.0%  1605   49.0  47.2  27.4 158.4  14.3  

Hop 1 is my router. Hop 2 is the wireless antenna on my property. Hop 8 is Hurricane Electric, a network provider in California, and beyond that is the public Internet.

But what’s going on between hops 3 and 7? I used to think this was the wireless nodes in my WISP, that hop 3 was the first radio and hop 4 was the second and so on. But looking at that average ping time I realize there’s no latency between 3 and 7. So now I think that hop 3 must be the first bit of wired infrastructure at my ISP, and that hops 2-3 are the sum total of all fixed wireless links. Perhaps they are acting as bridges, transparent at the IP layer. That’s how my own Ubiquiti nodes operate, I actually have 2 Ubiquity M2s running between hops 1 and 2 that are invisible to mtr.

FWIW the boxes at hops 3-5 look to be running MikroTik RouterOS. That’s also consistent with wired infrastructure; my wireless antenna at hop 2 is a Cambium device. No idea what 6 and 7 are. I don’t want to freak out my ISP by probing too hard.

One reason I’m looking at this so closely is I’m trying to understand the 2.3% packet loss shown at hop 2. That looks like it’s to my own equipment and I should be able to fix that. But every test I’ve done directly shows 0 packet loss to that device, the Cambium antenna up in my tree. Now my theory is the packet loss is actually in the wireless network between hops 2 and 3, the WISP’s wireless infrastructure. MTR can’t report it directly because those devices aren’t visible at the IP layer, so it just credits the packet loss to the last IP hop in the route, hop 2.

I think I see a similar thing when I mtr backwards back into my router at the WISP from a public Internet host; there’s no latency in my ISP’s network on the way in until a high latency gap at the last hop. The route back is different from the route out, which makes direct comparison a bit trickier.


I did a ping test to, the edge of my ISP’s network.

51 packets transmitted, 51 received, 0% packet loss, time 50076ms
rtt min/avg/max/mdev = 17.645/38.194/84.315/14.119 ms

I also asked my neighbor to do one.

52 packets transmitted, 52 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 17.737/29.401/53.861/8.731 ms

So his latency is 9ms better than mine. Significantly less jitter and worst case, too. I believe the difference between us is one radio hop. He has a radio link directly to Twin Cities Church. I think I have two hops, one north to a house and then from there south to the church.

I’d thought the church was where the wired internet began, it’s a major hub for the WISP. But those latency numbers suggest there’s possibly more wireless. The WISP’s office is down in Alta Sierra. The distances involved are so short I don’t think signal propagation time matters; it’s at most 20km, or 0.07ms at the speed of light. Not relevant. Processing time on the antenna relays though, not to mention congestion, those matter. Perhaps it’s 9ms per wireless hop, based on my measurement of my own link. We have ~20ms of latency unaccounted for, that suggests there are two more wireless hops from the church to the wired infrastructure.