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Latency 500ms+ starting yesterday on gigabit tier

New Poster

Latency 500ms+ starting yesterday on gigabit tier

Background: I have a CM1000 which has been happily running since the first month of gigabit offerings in my area about 2 years ago. I have never had high latency, and beyond some intermittent outages the service has been fine (pricing and "usage fees" aside). I am a computer programmer and often work from home. Today I started noticing intermittent strange behavior from my devices - slow to connect to sites, hiccups in voip, etc.

 

The TLDR is the latency is just too high:

Pinging comcast.com [69.252.80.75] with 32 bytes of data:
Reply from 69.252.80.75: bytes=32 time=710ms TTL=55
Reply from 69.252.80.75: bytes=32 time=527ms TTL=55
Reply from 69.252.80.75: bytes=32 time=563ms TTL=55
Reply from 69.252.80.75: bytes=32 time=728ms TTL=55

Ping statistics for 69.252.80.75:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 527ms, Maximum = 728ms, Average = 632ms

 

 

From inside the house, there is no problem with the router, the cabling, or the LAN-side NIC in the CM1000:

Pinging 192.168.100.1 with 32 bytes of data:
Reply from 192.168.100.1: bytes=32 time<1ms TTL=63
Reply from 192.168.100.1: bytes=32 time<1ms TTL=63
Reply from 192.168.100.1: bytes=32 time<1ms TTL=63
Reply from 192.168.100.1: bytes=32 time<1ms TTL=63

Ping statistics for 192.168.100.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

 

 

I have checked my signal levels in the CM1000, and they appear to be fine:

<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR / MER Unerrored Codewords Correctable Codewords Uncorrectable Codewords
1 Locked QAM256 42 699000000 Hz 11.6 dBmV 36.6 dB 180596562 0 0
2 Locked QAM256 17 549000000 Hz 10.2 dBmV 38.1 dB 179544357 0 0
3 Locked QAM256 18 555000000 Hz 10.4 dBmV 38.2 dB 179547795 0 0
4 Locked QAM256 19 561000000 Hz 10.4 dBmV 38.1 dB 179551500 0 0
5 Locked QAM256 20 567000000 Hz 10.1 dBmV 38.2 dB 179555536 0 0
6 Locked QAM256 21 573000000 Hz 10.1 dBmV 38.2 dB 179558977 0 0
7 Locked QAM256 22 579000000 Hz 10.2 dBmV 38.2 dB 179562530 0 0
8 Locked QAM256 23 585000000 Hz 10.3 dBmV 38.2 dB 179566062 0 0
9 Locked QAM256 24 591000000 Hz 10.4 dBmV 38.3 dB 179569961 0 0
10 Locked QAM256 25 597000000 Hz 10.8 dBmV 38.1 dB 179574095 0 0
11 Locked QAM256 26 603000000 Hz 11.0 dBmV 38.2 dB 179577259 0 0
12 Locked QAM256 27 609000000 Hz 11.0 dBmV 38.1 dB 179581213 0 0
13 Locked QAM256 28 615000000 Hz 11.3 dBmV 38.1 dB 179585374 0 0
14 Locked QAM256 29 621000000 Hz 11.4 dBmV 38.1 dB 179588561 0 0
15 Locked QAM256 30 627000000 Hz 11.4 dBmV 38.1 dB 179592005 0 0
16 Locked QAM256 31 633000000 Hz 11.6 dBmV 37.9 dB 179596449 0 0
17 Locked QAM256 32 639000000 Hz 11.4 dBmV 37.9 dB 179602696 0 0
18 Locked QAM256 33 645000000 Hz 11.4 dBmV 37.6 dB 179606484 0 0
19 Locked QAM256 34 651000000 Hz 11.4 dBmV 37.5 dB 179610087 0 0
20 Locked QAM256 35 657000000 Hz 11.1 dBmV 37.4 dB 179613580 0 0
21 Locked QAM256 36 663000000 Hz 11.2 dBmV 37.3 dB 179617274 0 0
22 Locked QAM256 37 669000000 Hz 11.2 dBmV 37.2 dB 179621835 0 0
23 Locked QAM256 38 675000000 Hz 10.9 dBmV 37.0 dB 179624921 0 0
24 Locked QAM256 39 681000000 Hz 10.9 dBmV 36.9 dB 179628440 0 0
25 Locked QAM256 40 687000000 Hz 11.3 dBmV 36.4 dB 179632974 0 0
26 Locked QAM256 41 693000000 Hz 11.3 dBmV 36.6 dB 179636047 0 0
27 Locked QAM256 43 705000000 Hz 12.0 dBmV 36.5 dB 179639851 0 0
28 Locked QAM256 44 711000000 Hz 12.0 dBmV 36.2 dB 179643481 0 0
29 Locked QAM256 45 717000000 Hz 12.1 dBmV 36.2 dB 179647471 0 0
30 Locked QAM256 46 723000000 Hz 12.3 dBmV 36.0 dB 179649982 0 0
31 Locked QAM256 47 729000000 Hz 12.5 dBmV 36.0 dB 179649466 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 0
<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power
1 Locked ATDMA 1 36500000 Hz 32.8 dBmV
2 Locked ATDMA 2 30100000 Hz 33.5 dBmV
3 Locked ATDMA 3 23700000 Hz 33.5 dBmV
4 Locked ATDMA 4 17300000 Hz 33.0 dBmV
5 Not Locked Unknown 0 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Hz 0.0 dBmV

 

 

I have checked the error logs on the CM1000, and there are 1-2 errors every 2 months or so, but very very rare.

 

 

Tracert to comcast.com shows same as ping:

Tracing route to comcast.com [69.252.80.75]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 192.168.1.1
2 465 ms 483 ms 530 ms cm-1-acr02.arvada.co.denver.comcast.net [96.120.12.169]
3 253 ms 271 ms 187 ms 96.110.242.193
4 95 ms 69 ms 83 ms ae-9-ar01.denver.co.denver.comcast.net [68.86.128.129]
5 367 ms 384 ms 448 ms be-33652-cr02.1601milehigh.co.ibone.comcast.net [68.86.92.121]
6 426 ms 345 ms 378 ms ae0-0-ar03-d.cmc.co.ndcwest.comcast.net [68.86.90.74]
7 428 ms 453 ms 426 ms be-10-ur25-d.cmc.co.ndcwest.comcast.net [68.86.132.26]
8 291 ms 375 ms 397 ms po-5-sw303a-d.cmc.co.ndcwest.comcast.net [162.151.85.194]
9 413 ms 371 ms 319 ms urlrw01.cable.comcast.com [69.252.80.75]

Trace complete.

 

 

I feel like the problem is really just comcast here. What can I do to resolve the problem? I know that speaking to a rep on the phone will just yield "speeds show fine" which they do, if you ignore the insane latency it takes to rev up to the eventual data flow.

New Poster

Re: Latency 500ms+ starting yesterday on gigabit tier

I should note that I did try resetting the modem several times (as well as the rest of my internal network). I also tried leaving it off for a few hours and starting it back up.

 

Tomorrow I will go and purchase a new modem from a local retailer to see if it resolves the issue.

New Poster

Re: Latency 500ms+ starting yesterday on gigabit tier

As of this morning, the problem is no longer presenting (no changes from my end, I did not wind up changing equipment yet). I will check back in later this week with updates on whether the conditions remain good.
Expert

Re: Latency 500ms+ starting yesterday on gigabit tier

FWIW, if this Is this with a WiFi connection, for a test, see if a computer hardwired directly to the router / gateway device with an ethernet cable has the same problem if it comes back.



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New Poster

Re: Latency 500ms+ starting yesterday on gigabit tier

Just as a note, the problem was present on both ethernet and wifi last night. I have a large wired 10/100/1000 switch with a 48 Gbps backplane, and a managed commercial AC wireless system. There were no issues pinging the router or CM1000 internally from the network on either wired or wireless, and no issues communicating between devices on the house's intranet.

 

At this point I have to conclude the issue was on Comcast's end. To their credit, it seems the issue was resolved on Friday night possibly due to routine maintenance or equipment reboots. I will report back in a week to see if the problem stays gone.