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Very High Latency and Jitter

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Frequent Visitor

Very High Latency and Jitter

I'm trying to access a remote work site via RDP.  The remote end is a small rural provider; the local end here at home is Xfinity with the Blast! option, good to 175 down and 10 up.

 

Remote desktop is unusable due to severe latency (up to 1.5 seconds) and extreme jitter.  Using WinMTR I see the rural remote end has excellent connectivity -- pings averaging 24 to 30 mSec with low jitter.  I verified this in person at the remote site as well, the connection there is 6 down/3 up but the latency and jitter are excellent.

 

WinMTR and traceroute show that the packets leaving the remote site run into trouble at the very last hop near my home at 

 

c-73-66-XX-XXX.hsd1.ca.comcast.net    Average ping: 504 mSec, worst 1418 mSec

 

Home modem is a Zoom DOCSIS 3.0  8x4  5431J

Downstream SNR ranges from 41.3 to 41.9 dB, power ranges from 6.3 to 9.0 dBmV

Upstream power 45.0 to 46.8 dBmV

 

Router logs at both ends report nothing unusual.  The LANs at both ends are Cat 5, no wireless involved.

 

Any ideas?  thanks.   

 

 

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Expert

Re: Very High Latency and Jitter

What do the Zoom modem's RF error log entries look like ? Please post all of the signal status figures as well for us to see. Take a screenshot or copy and paste the text.



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Frequent Visitor

Re: Very High Latency and Jitter

EG,  my modem does not keep an RF error log, or at least it's not available through the admin screens.  Here's the connection info:

 

Downstream Bonded Channels
Channel Modulation Frequency Power SNR Correctables Uncorrectables
1 QAM256 447000000 Hz 5.9 dBmV 41.1 dB 32111 18814
2 QAM256 453000000 Hz 6.7 dBmV 41.4 dB 26063 16539
3 QAM256 459000000 Hz 6.9 dBmV 41.4 dB 26814 14513
4 QAM256 471000000 Hz 8.0 dBmV 41.9 dB 26844 15290
5 QAM256 477000000 Hz 8.5 dBmV 41.9 dB 26377 14562
6 QAM256 483000000 Hz 8.5 dBmV 41.9 dB 28241 15824
7 QAM256 489000000 Hz 8.7 dBmV 41.8 dB 24844 15218
8 QAM256 495000000 Hz 8.5 dBmV 41.6 dB 26907 16977

 

Total Correctables Total Uncorrectables
218201 127737



Upstream Bonded Channels
Channel US Channel Type Symbol Rate Frequency Power
1 ATDMA 5120 Ksym/sec 32300000 Hz 46.0 dBmV
2 ATDMA 5120 Ksym/sec 19300000 Hz 45.3 dBmV
3 ATDMA 5120 Ksym/sec 25700000 Hz 45.8 dBmV
4 ATDMA 5120 Ksym/sec 38700000 Hz 47.0 dBmV

 

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 447000000 Hz Locked
Connectivity State OK Operational
Boot State    
Configuration File OK  
Security Enabled BPI+

 

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Expert

Re: Very High Latency and Jitter

I had that modem, and it always did, unless something has changed !



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Gold Problem Solver

Re: Very High Latency and Jitter


@Elliott_James wrote: ... my modem does not keep an RF error log, or at least it's not available through the admin screens. ...

My 5341J has one but to reach it, I have to log in, and then click bookmarked link http://192.168.100.1/RgEventLog.asp.

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Frequent Visitor

Re: Very High Latency and Jitter

BruceW: thanks for the link... there's only a handful of error reports over the last few weeks:

 

Wed Jul 01 05:33:37 2020    Error (4)   ToD request sent - No Response received;CM-MAC=00:1c:7b:e6:20... 
 Sat Jun 27 08:00:13 2020    Critical (3)   Started Unicast Maintenance Ranging - No Response received - ... 
 Wed Jun 24 04:44:24 2020    Error (4)   ToD request sent - No Response received;CM-MAC=00:1c:7b:e6:20... 
 Wed Jun 24 03:41:46 2020    Critical (3)   Started Unicast Maintenance Ranging - No Response received - ... 
 Wed Jun 17 04:42:06 2020    Error (4)   ToD request sent - No Response received;CM-MAC=00:1c:7b:e6:20... 
 Sun Jun 14 07:35:43 2020    Critical (3)   Started Unicast Maintenance Ranging - No Response received - ... 
 Wed Jun 10 04:41:50 2020    Error (4)   ToD request sent - No Response received;CM-MAC=00:1c:7b:e6:20... 

 

To show how bad my connection is, here's the pings from home to the remote work site

(I'm using a UDP VPN. The remote IP address is virtual)

 

VIA COMCAST

64 bytes from 10.144.251.121: icmp_seq=1 ttl=64 time=3036 ms
64 bytes from 10.144.251.121: icmp_seq=2 ttl=64 time=2075 ms
64 bytes from 10.144.251.121: icmp_seq=3 ttl=64 time=1328 ms

 

VIA VERIZON SMARTPHONE TETHER

64 bytes from 10.144.251.121: icmp_seq=1 ttl=64 time=88.6 ms
64 bytes from 10.144.251.121: icmp_seq=2 ttl=64 time=68.8 ms
64 bytes from 10.144.251.121: icmp_seq=3 ttl=64 time=92.8 ms

 

What in the Comcast chain is holding my  packets for so long?

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Gold Problem Solver

Re: Very High Latency and Jitter


@Elliott_James wrote: ... there's only a handful of error reports over the last few weeks: ...

Not sure what to make of the event log. Three "Unicast Maintenance Ranging - No Response" entries in 10 days doesn't seem excessive. OTOH I've never seen "ToD Request sent - No Response" messages in my 5341's log, and it's been running for 6 years. A difference in the CMTS config possibly? Perhaps @EG can offer some insight.

 

Ping tells us that the RTT is high, but that's all. Can you run a Tracert (Windows) or Traceroute (Mac and *nix) to the target IP and post those results? That might allow us to see where the slowdown is.

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Frequent Visitor

Re: Very High Latency and Jitter


@BruceW wrote:

@Elliott_James wrote: ... there's only a handful of error reports over the last few weeks: ...

Not sure what to make of the event log. Three "Unicast Maintenance Ranging - No Response" entries in 10 days doesn't seem excessive. OTOH I've never seen "ToD Request sent - No Response" messages in my 5341's log, and it's been running for 6 years. A difference in the CMTS config possibly? Perhaps @EG can offer some insight.

 

Ping tells us that the RTT is high, but that's all. Can you run a Tracert (Windows) or Traceroute (Mac and *nix) to the target IP and post those results? That might allow us to see where the slowdown is.


Here's the WinMTR (similar to Tracert) that I ran at the remote site probing my home IP

You can see mostly all is well until I hit the last hop:

|-----------------------------------------------------------------------------------------------|
|                                           WinMTR statistics                                   |
|                            Host              -   %  | Sent | Recv | Best | Avrg | Wrst | Last |
|-----------------------------------------------------|------|------|------|------|------|------|
| [Remote]                         192.168.1.1 -    0 |   52 |   52 |    0 |    0 |    0 |    0 |
|                                     XX.X.X.X -    0 |   52 |   52 |    0 |    0 |   24 |    0 |
|001.XXX-93-216-nokia-dsl.dynamic.surewest.net -    0 |   52 |   52 |   12 |   24 |   50 |   17 |
|        133.161-60-66-biz-static.surewest.net -    2 |   50 |   49 |   13 |   25 |   67 |   18 |
|                               204.154.217.70 -    2 |   50 |   49 |   14 |   25 |   61 |   29 |
|                              204.154.217.247 -    0 |   52 |   52 |   13 |   28 |   54 |   13 |
|                              204.154.217.168 -    2 |   50 |   49 |   12 |   30 |  159 |   20 |
|                       sjo-b21-link.telia.net -    5 |   49 |   47 |    0 |   25 |   47 |   24 |
|                      palo-b24-link.telia.net -    5 |   49 |   47 |   22 |   32 |  153 |   32 |
|   be-200-pe11.529bryant.ca.ibone.comcast.net -    2 |   50 |   49 |   20 |   33 |   60 |   26 |
|  be-3111-cr02.sunnyvale.ca.ibone.comcast.net -    0 |   52 |   52 |   24 |   37 |  168 |   25 |
|    ae-79-ar01.sacramento.ca.ccal.comcast.net -    0 |   52 |   52 |   24 |   39 |  168 |   25 |
|   ae-2-rur101.sacramento.ca.ccal.comcast.net -    0 |   52 |   52 |   22 |   47 |  569 |   24 |
|                                68.87.212.158 -    2 |   50 |   49 |   23 |   35 |   75 |   42 |
| [Home]    c-XX-XX-XX-XXX.hsd1.ca.comcast.net -    0 |   52 |   52 |  131 | 1008 | 2112 |  304 |
|_____________________________________________________|______|______|______|______|______|______|

 

 

 

 

 

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Frequent Visitor

Re: Very High Latency and Jitter

Wow -- problem completely fixed with a modem restart.  I should have done that first before starting this thread.  Sorry to waste everyone's time.  Lesson learned: when there's a connectivity issue, step 1, restart modem, every time!