Pinging modem spikes?



  • I have a sb6120 modem, Comcast as the ISP.

    I have had 2 pfsense installations that have done this:
    First one was: 2xintel nics, 2.0ghz p4, 512 ram

    Second one was: 1x intel nic(lan) + onboard nic(wan)
    e5300 @ 3.35ghz, 6 gigs of ram.

    I ping the modem from Pfsense, and even a computer outside, and I get random ping spikes.

    Here is the output from pfsense

    64 bytes from 192.168.100.1: icmp_seq=0 ttl=64 time=5.890 ms
    64 bytes from 192.168.100.1: icmp_seq=1 ttl=64 time=0.409 ms
    64 bytes from 192.168.100.1: icmp_seq=2 ttl=64 time=0.329 ms
    64 bytes from 192.168.100.1: icmp_seq=3 ttl=64 time=0.301 ms
    64 bytes from 192.168.100.1: icmp_seq=4 ttl=64 time=0.392 ms
    64 bytes from 192.168.100.1: icmp_seq=5 ttl=64 time=0.416 ms
    64 bytes from 192.168.100.1: icmp_seq=6 ttl=64 time=0.385 ms
    [b]64 bytes from 192.168.100.1: icmp_seq=7 ttl=64 time=20.977 ms[/b]
    64 bytes from 192.168.100.1: icmp_seq=8 ttl=64 time=0.332 ms
    64 bytes from 192.168.100.1: icmp_seq=9 ttl=64 time=0.407 ms
    
    

    Why is there a random ping jump? I have tried 2 different nics for this, one Intel and the other realtek(I think).

    I can ping the Lan port on pfsense fine from another computer, always below 1ms.

    Anyone else have this problem? Do you think my modem is the issue and not pfsense? I would unplug pfsense and just hook up a lappy to test, but I will get yelled at by someone else on the Internet(brother, etc)

    Anyone else have this issue?



  • Try pinging your isp gateway in the same fashion.  On a busy node this could be hard to distinguish whether your seeing the same problem or just the overloaded node.

    Try pinging your modem and wiggling the patch cord between your modem and router.

    Bump the modem around a bit as you ping it.  You never know if you have a bad solder joint inside thats an issue…

    Shouldn't matter to the modem local address but make sure your cable connections are tight all the way to the side of your house including tv's.

    I have a Linksys BEFCMU10 that I ping occasionally during maintenance and never see fluctuation in latency at all. Even under load.



  • This is pinging the node, same awfulness

    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=9ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=11ms TTL=25
    Reply from 76.21.108.1: bytes=32 time=30ms TTL=25
    Reply from 76.21.108.1: bytes=32 time=42ms TTL=25
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=23ms TTL=25
    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=53ms TTL=25
    Reply from 76.21.108.1: bytes=32 time=7ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    Reply from 76.21.108.1: bytes=32 time=8ms TTL=254
    

    This is running sort of simultaneously to this

    Reply from 192.168.100.1: bytes=32 time=6ms 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
    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
    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
    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
    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
    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=10ms TTL=6
    Reply from 192.168.100.1: bytes=32 time<1ms TTL=63
    Reply from 192.168.100.1: bytes=32 time<1ms TTL=63
    

    The modem actually was opened, and I used a chip clip, and connected wires to that to JTAG it. I had it running Alpha for a bit, but then when I was done testing, I just let it accept the firmware update from Comcast.

    I never actually soldered directly onto the modem.

    However on pingtest.net I get this:

    Will try your suggestions



  • Argh, just switched the intel nic from a cat5 cable to a cat6 cable, still same problem. Made sure it was tightened, and made sure all the coax connections were tight, even though as you said that shouldn't effect ping times to the modem.



  • Is there anything in the modem logs?

    Do you own it or is it rented?

    If you own yours you might consider renting one from your ISP for further testing. Or borrow one from a friend…

    Do you know if this is a recent change?



  • Nah, I own it.

    I get t3 timeouts daily, so that's a problem. Signals are well within DOCSIS.

    !
    Though that's getting to another issue altogether.

    Here is my modem log

    
     2011 20:48:57	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot from GUI/Configuration page ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Jan 15 2011 03:20:36	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 13 2011 15:30:00	6-Notice	I502.0	Received REG-RSP while in REG-HOLD1 state;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 13 2011 15:13:30	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Jan 04 2011 19:42:11	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Dec 31 2010 01:37:40	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Dec 25 2010 01:04:53	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Dec 24 2010 10:45:37	3-Critical	R04.0	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Dec 24 2010 10:45:13	3-Critical	T05.0	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
    Dec 24 2010 10:30:16	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Jan 01 1970 00:00:12	6-Notice		Cable Modem Reboot due to power reset ;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    Dec 23 2010 02:43:43	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=xxxxxxxxxxxxxx;CMTS-MAC=xxxxxxxxxxxxxx;CM-QOS=1.1;CM-VER=3.0;
    

    I don't have anybody's to borrow unfortunately.
    I suppose I could rent one from Comcast, I hope to get a dpc3000 if I do. Looks like a very nice modem. Also I don't know if it is a recent change, but I believe having this problem for a while. I don't think I had this problem on my old sb5101, but I'm not sure.



  • I was gonna bring up the idea of a failing power supply but didn't because I believe its inside the modem as in the earlier models instead of using an external supply…

    I believe you found your issue. You might do a little looking at the power supply section and see if its fixable. You mention you have been inside it before...

    Before I had my spare test unit I would have my client rent one for a month or two just for testing if I suspected or needed to prove to the cable company that it was not the customer owned equipment causing their problems. Something we needed to do around here way to often.



  • I have a spare power supply for it, I'll test that.
    Thing is though, I didn't do all that much to the modem, since I have abused sb5101s a lot more and they never whined… I thought I was pretty delicate with this one.

    EDIT: Same problem with the new power supply.

    Guess I'll rent a modem from Comcast, or just find a dpc3000 on ebay.



  • You could try wiring it up to a 12v battery and see if the errors go away…  Wall-worts are not the cleanest dc power most of the time and the engineers usually build into the device a power supply section with caps and voltage regulator(s)...  Im betting a capacitor or two has gone south. (Not at all uncommon)

    My guess is that this is the cause of the ping spikes but till its fixed you would never know...



  • Hmm, well it is hooked up to a UPS. I'll try it without the UPS.

    EDIT: same thing either way : /


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