C

Wednesday, September 18th, 2024 7:06 PM

How to resolve packet loss in Comcast network

We've been having significant internet issues for weeks where the connection drops or times out. Latency often goes over 5s, so any games that use the internet are unplayable.

I did some digging and it looks like a specific Comcast router is dropping a high % of traffic. Its name is be-36111-cs01.seattle.wa.ibone.comcast.net.

Here's the output from mtr showing the packet loss in the network.

US-MBP-XYF45K (192.168.1.101) -> 8.8.8.8 (8.8.8.8)                                                                                                                         2024-09-18T12:04:32-0700
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                                                                                                                                           Packets               Pings
 Host                                                                                                                                                    Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. clamnet-media-3                                                                                                                                       0.0%   315    1.5   1.3   0.6  10.6   0.8
 2. 100.93.161.66                                                                                                                                         1.3%   315   13.5  13.0   4.6  37.2   5.0
 3. po-319-345-rur401.bellevue.wa.seattle.comcast.net                                                                                                     1.9%   315   10.3  12.3   7.1  32.4   4.0
 4. po-2-rur402.bellevue.wa.seattle.comcast.net                                                                                                           1.3%   315   12.4  12.3   6.1  50.3   4.2
 5. po-400-xar02.bellevue.wa.seattle.comcast.net                                                                                                          1.6%   315   11.3  12.7   6.3  36.6   4.5
 6. be-300-arsc1.seattle.wa.seattle.comcast.net                                                                                                           2.5%   315   17.5  14.0   8.5  92.3   6.1
 7. be-36111-cs01.seattle.wa.ibone.comcast.net                                                                                                           45.5%   315   13.1  14.1   9.8  32.5   3.8
 8. be-2112-pe12.seattle.wa.ibone.comcast.net                                                                                                             3.5%   315   12.7  14.3   9.8  44.4   4.4
 9. 50.248.117.18                                                                                                                                         3.2%   315   13.0  13.7   7.0  32.2   3.8
10. 108.170.255.127                                                                                                                                       1.3%   315   12.0  15.0   8.3  41.3   4.9
11. 142.251.50.243                                                                                                                                        3.2%   315   14.7  14.2   7.9  32.3   4.4
12. dns.google                                                                                                                                            0.6%   314   14.1  14.2   8.9  34.9   4.7

As you can see, the be-36111-cs01.seattle.wa.ibone.comcast.net router is dropping ~45% of packets, which seems highly likely to be the root cause. Could be that the whole router is bad or just a bad cable. I cannot fix this on my end because it's in some Comcast datacenter. Please advise.

Gold Problem Solver

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26K Messages

2 months ago

Hop 12 shows less packet loss than hop 2, so the "loss" at hop 7 is likely more apparent than real, and probably not significant. Please see https://www.dslreports.com/faq/14068. The fact that hops beyond than ones you are concerned received the trace packets indicates that the router at that address is doing its job: forwarding data packets. The hop 7 router's occasional delay in or failure to respond to trace packets, while annoying, is most likely not actually slowing down data transfer. If it was we'd see high RTT values and/or packet loss in all subsequent hops.

Interpreting trace results is tricky. What appears to be "late" or is reported as "lost" could mean 1) the packet did not reach or was delayed in reaching that hop, or 2) the router at that hop didn't reply or was slow to reply, or 3) the reply from that hop didn't make it back or was delayed in making it back to the trace program.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

3 Messages

Note that this is mtr not traceroute output.

Ok, I'll buy that the router could be too busy to respond so it looks like packet loss. I do see some overall packet loss though, so it does seem like a big coincidence. Here's the output from ping.

PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=115 time=10.977 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=115 time=13.704 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=115 time=11.359 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=115 time=12.997 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=115 time=14.354 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=115 time=12.068 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=115 time=11.241 ms
Request timeout for icmp_seq 7
64 bytes from 8.8.8.8: icmp_seq=8 ttl=115 time=21.148 ms
64 bytes from 8.8.8.8: icmp_seq=9 ttl=115 time=11.783 ms
64 bytes from 8.8.8.8: icmp_seq=10 ttl=115 time=11.754 ms
64 bytes from 8.8.8.8: icmp_seq=11 ttl=115 time=15.367 ms
64 bytes from 8.8.8.8: icmp_seq=12 ttl=115 time=13.250 ms
Request timeout for icmp_seq 13
64 bytes from 8.8.8.8: icmp_seq=14 ttl=115 time=33.103 ms
64 bytes from 8.8.8.8: icmp_seq=15 ttl=115 time=10.633 ms
64 bytes from 8.8.8.8: icmp_seq=16 ttl=115 time=13.327 ms
64 bytes from 8.8.8.8: icmp_seq=17 ttl=115 time=11.994 ms
64 bytes from 8.8.8.8: icmp_seq=18 ttl=115 time=11.841 ms
64 bytes from 8.8.8.8: icmp_seq=19 ttl=115 time=14.643 ms
etc until
--- 8.8.8.8 ping statistics ---
200 packets transmitted, 193 packets received, 3.5% packet loss
round-trip min/avg/max/stddev = 9.523/14.410/57.019/5.568 ms

What this looks like for online gaming is that it's fine most of the time, but every few minutes you will get disconnected or get a 5s+ lag spike. I do not know of any other way of narrowing down the issue - suggestions welcome.
If the issue was on my router or cable modem, I would expect mtr to show packet loss at the early hops, but it doesn't, so I don't actually know what I can do to resolve the problem.

Official Employee

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1.5K Messages

Hello, @Clamatius. Thanks for reaching our team on Forums regarding your internet concerns. We can certainly help and look into this, please send a DM with your full name and the full service address to assist.

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Gold Problem Solver

 • 

26K Messages

2 months ago

... every few minutes you will get disconnected or get a 5s+ lag spike. I do not know of any other way of narrowing down the issue ...

Start by seeing if your modem or gateway's signal stats are in spec, see Internet Troubleshooting Tips. If your signals are in spec and stable there isn't much more you can do except to bug Comcast/Xfinity to find and fix the problem. If an employee does not respond to your message here, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit (approx $100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

(edited)

3 Messages

Thanks Bruce, much appreciated. I'll work through the troubleshooting stuff this weekend and follow up with Comcast as per Gabby's message above if (as seems likely) it doesn't seem to be on my end.

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