Xiaofeng_Xu's profile

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15 Messages

Wednesday, August 31st, 2022 5:28 PM

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high ping and packet loss

Hi,

The last several days I have been experiencing high ping and sometimes packet loss. The problem is more obvious if I ping bing.com. Pinging google.com gives better results. My modem signals seem to be ok. Appreciate any help here.

Thanks.

Frequent Visitor

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15 Messages

3 years ago

Ping results below. As you can see, the results are vastly different.

PING bing.com (13.107.21.200): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
64 bytes from 13.107.21.200: icmp_seq=0 ttl=118 time=2025.828 ms
64 bytes from 13.107.21.200: icmp_seq=1 ttl=118 time=1145.836 ms
64 bytes from 13.107.21.200: icmp_seq=2 ttl=118 time=143.030 ms
64 bytes from 13.107.21.200: icmp_seq=3 ttl=118 time=102.859 ms
64 bytes from 13.107.21.200: icmp_seq=4 ttl=118 time=16.007 ms
64 bytes from 13.107.21.200: icmp_seq=5 ttl=118 time=12.954 ms
64 bytes from 13.107.21.200: icmp_seq=6 ttl=118 time=968.728 ms
64 bytes from 13.107.21.200: icmp_seq=7 ttl=118 time=732.121 ms
64 bytes from 13.107.21.200: icmp_seq=8 ttl=118 time=1593.017 ms
64 bytes from 13.107.21.200: icmp_seq=9 ttl=118 time=764.634 ms
64 bytes from 13.107.21.200: icmp_seq=10 ttl=118 time=306.109 ms
64 bytes from 13.107.21.200: icmp_seq=11 ttl=118 time=337.326 ms
64 bytes from 13.107.21.200: icmp_seq=12 ttl=118 time=46.328 ms
64 bytes from 13.107.21.200: icmp_seq=13 ttl=118 time=2116.417 ms
64 bytes from 13.107.21.200: icmp_seq=14 ttl=118 time=2316.318 ms

PING google.com (172.217.0.174): 56 data bytes
64 bytes from 172.217.0.174: icmp_seq=0 ttl=56 time=11.249 ms
64 bytes from 172.217.0.174: icmp_seq=1 ttl=56 time=10.499 ms
64 bytes from 172.217.0.174: icmp_seq=2 ttl=56 time=10.661 ms
64 bytes from 172.217.0.174: icmp_seq=3 ttl=56 time=11.709 ms
64 bytes from 172.217.0.174: icmp_seq=4 ttl=56 time=16.021 ms
64 bytes from 172.217.0.174: icmp_seq=5 ttl=56 time=10.707 ms
64 bytes from 172.217.0.174: icmp_seq=6 ttl=56 time=10.744 ms
64 bytes from 172.217.0.174: icmp_seq=7 ttl=56 time=10.837 ms
64 bytes from 172.217.0.174: icmp_seq=8 ttl=56 time=12.385 ms
64 bytes from 172.217.0.174: icmp_seq=9 ttl=56 time=16.718 ms
64 bytes from 172.217.0.174: icmp_seq=10 ttl=56 time=10.851 ms
64 bytes from 172.217.0.174: icmp_seq=11 ttl=56 time=13.541 ms
64 bytes from 172.217.0.174: icmp_seq=12 ttl=56 time=12.240 ms
64 bytes from 172.217.0.174: icmp_seq=13 ttl=56 time=10.708 ms
64 bytes from 172.217.0.174: icmp_seq=14 ttl=56 time=10.801 ms
64 bytes from 172.217.0.174: icmp_seq=15 ttl=56 time=11.012 ms
64 bytes from 172.217.0.174: icmp_seq=16 ttl=56 time=10.386 ms
64 bytes from 172.217.0.174: icmp_seq=17 ttl=56 time=10.548 ms
64 bytes from 172.217.0.174: icmp_seq=18 ttl=56 time=10.806 ms
64 bytes from 172.217.0.174: icmp_seq=19 ttl=56 time=14.160 ms

Expert

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110.3K Messages

3 years ago

It's very likely that two different routes are being traversed to get to those two different server destinations. Posting the output of a traceroute to the IP address of that first host's server will perhaps reveal where the excessive latency / packet loss is occuring.

Frequent Visitor

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15 Messages

@EG​ it's like this

traceroute to 13.107.21.200 (13.107.21.200), 64 hops max, 52 byte packets
 1  unifi (192.168.1.1)  0.559 ms  0.264 ms  0.244 ms
 2  96.120.29.45 (96.120.29.45)  8.497 ms  8.383 ms  8.118 ms
 3  96.110.165.137 (96.110.165.137)  8.236 ms  8.379 ms  8.280 ms
 4  162.151.47.217 (162.151.47.217)  7.959 ms  3908.274 ms  1247.148 ms
 5  be-125-ar01.area4.il.chicago.comcast.net (68.86.188.93)  41.358 ms  9.447 ms  11.133 ms
 6  be-32231-cs03.350ecermak.il.ibone.comcast.net (96.110.40.57)  14.716 ms  10.441 ms
    be-32221-cs02.350ecermak.il.ibone.comcast.net (96.110.40.53)  10.179 ms
 7  be-2212-pe12.350ecermak.il.ibone.comcast.net (96.110.33.214)  15.096 ms
    be-2112-pe12.350ecermak.il.ibone.comcast.net (96.110.33.210)  15.835 ms
    be-2412-pe12.350ecermak.il.ibone.comcast.net (96.110.33.222)  16.423 ms
 8  50.248.117.178 (50.248.117.178)  25.008 ms  9.413 ms
    50.248.116.134 (50.248.116.134)  10.735 ms
 9  * * *
10  * *

Visitor

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1 Message

3 years ago

I've been having the same issue for months. I've had several Xfinity technicians come out. They think it's an issue on the poll out on the street. I can't seem to get help resolving the issue.

Frequent Visitor

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15 Messages

@user_9e8af1​ bummer. Now that we all work from home, it has become a major issue.

Problem Solver

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908 Messages

Hello @Xiaofeng_Xu and @user_9e8af1

 

Thank you for bringing the ping and packet loss issues to our attention. You have reached the right place for help. 

 

Please send a private message with your first and last name, as well as complete service address to "Xfinity Support". To do so, click on the chat icon located at the top right of this forums page.

 

  1. Click "Sign In" if necessary
  2. Click the "Direct Messaging" icon (upper right corner of this page)
  3. Click the "New message" (pencil and paper) icon
  4. Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list
  5. Type your message in the text area near the bottom of the window
  6. Press Enter to send your message

 

I no longer work for Comcast.

Expert

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110.3K Messages

3 years ago

Ok so the *alleged* excessive latency is in the Comcast regional router / webspace (hop number 4) but it does not carry through to the farther upstream routers or the destination server, so it is likely to be only ICMP packet based deprioritization / rate limiting that is being done by this router and is not true latency.

(edited)

Frequent Visitor

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15 Messages

@EG​ It actually is affecting my Teams calls etc. The remote parties said the latency was big and my voice broke up. I checked with several of my neighbors. They are having the same issue.

Frequent Visitor

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15 Messages

Today again in a morning meeting my voice was in and out. And people said the latency was high as well. It is very difficult to maintain a conversation.

Expert

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110.3K Messages

3 years ago

That could be due to a more local RF signal / connection quality / upstream impairment problem with the system rather than a being transit routing problem.

What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 or here http://10.0.0.1 

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.


What is the exact make and model number of the modem / gateway device ?

Is this with a WiFi connection ?

Frequent Visitor

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15 Messages

@EG​ Please see below for the signal information. The modem is a SURFboard S33. The issue can be seen on Ethernet connection as well.

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
17 Locked QAM256 621000000 Hz 1 dBmV 39 dB 28 0
2 Locked QAM256 531000000 Hz 1 dBmV 40 dB 0 0
3 Locked QAM256 537000000 Hz 1 dBmV 40 dB 0 0
4 Locked QAM256 543000000 Hz 1 dBmV 40 dB 0 0
5 Locked QAM256 549000000 Hz 1 dBmV 40 dB 0 0
6 Locked QAM256 555000000 Hz 1 dBmV 40 dB 0 0
7 Locked QAM256 561000000 Hz 1 dBmV 40 dB 0 0
8 Locked QAM256 567000000 Hz 0 dBmV 40 dB 0 0
9 Locked QAM256 573000000 Hz 0 dBmV 40 dB 0 0
10 Locked QAM256 579000000 Hz 0 dBmV 40 dB 0 0
11 Locked QAM256 585000000 Hz 1 dBmV 40 dB 0 0
12 Locked QAM256 591000000 Hz 1 dBmV 39 dB 0 0
13 Locked QAM256 597000000 Hz 1 dBmV 39 dB 0 0
14 Locked QAM256 603000000 Hz 1 dBmV 39 dB 0 0
15 Locked QAM256 609000000 Hz 0 dBmV 39 dB 0 0
16 Locked QAM256 615000000 Hz 1 dBmV 39 dB 0 0
18 Locked QAM256 627000000 Hz 1 dBmV 39 dB 7 27
19 Locked QAM256 633000000 Hz 1 dBmV 39 dB 14 29
20 Locked QAM256 639000000 Hz 0 dBmV 39 dB 48 50
21 Locked QAM256 645000000 Hz 0 dBmV 39 dB 211 129
22 Locked QAM256 651000000 Hz 0 dBmV 39 dB 699 690
23 Locked QAM256 657000000 Hz 0 dBmV 39 dB 2273 2982
24 Locked QAM256 663000000 Hz -1 dBmV 39 dB 7281 10115
25 Locked QAM256 669000000 Hz 0 dBmV 39 dB 16174 29563
26 Locked QAM256 675000000 Hz 0 dBmV 39 dB 39434 74920
27 Locked QAM256 681000000 Hz 0 dBmV 39 dB 87922 167364
28 Locked QAM256 687000000 Hz 0 dBmV 39 dB 220890 320527
29 Locked QAM256 693000000 Hz 0 dBmV 39 dB 554923 528621
30 Locked QAM256 699000000 Hz 0 dBmV 39 dB 1230298 778893
31 Locked QAM256 705000000 Hz 0 dBmV 39 dB 1236676 897305
32 Locked QAM256 711000000 Hz 0 dBmV 39 dB 215550 251266
37 Locked OFDM PLC 762000000 Hz 0 dBmV 38 dB 242554040

Expert

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110.3K Messages

3 years ago

Those are all good but you didn't include the upstream power level values ?

And are there any modem RF error log entries being shown ? If so, please post them as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. The posting of personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

Frequent Visitor

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15 Messages

@EG​ Please see the information below. Again, thank you very much for the support. Really appreciate it.

Upstream Bonded Channels
Channel ID Lock Status US Channel Type Frequency Width Power
5 Locked SC-QAM 35600000 Hz 6400000 38.3 dBmV
6 Locked SC-QAM 29200000 Hz 6400000 38.8 dBmV
7 Locked SC-QAM 22800000 Hz 6400000 38.8 dBmV
8 Locked SC-QAM 16400000 Hz 6400000 38.5 dBmV
10 Locked SC-QAM 40400000 Hz 3200000 37.3 dBmV



Date TimeEvent LevelDescription31/12/1969
18:00:153CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.31/12/1969
18:00:203SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;31/12/1969
18:00:223CMSTATUS:US_Diplexer_Mode_Change_Ignored:TLV-9, 42MHz.31/12/1969
18:00:393CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.31/12/1969
18:00:393CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.31/12/1969
18:00:393CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.3/7/2022
11:55:003SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;3/7/2022
18:00:153CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz.31/12/1969

Expert

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110.3K Messages

3 years ago

@Xiaofeng_Xu 

Ok so even though the signal status values looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) / an upstream channel / return path impairment somewhere.


There are other signal stat values that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.


I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

Frequent Visitor

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15 Messages

@EG​ Thank you so much. Really appreciate it!

Expert

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110.3K Messages

3 years ago

@Xiaofeng_Xu Quite welcome !

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