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  1. #1
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    Packet Loss on PING

    Having just spent a happy hour on the phone to Blueyonder (cable company) technical support, I wonder whether anyone has any better ideas than I about the following matter.

    PC is a Fujitsu Siemens, 3200 MHz Athlon, 2 GB memory, XP Home SP2, acres of hard disk space, no viruses, NIS 2006, no hardware firewall
    connected by a 2 m Ethernet patch cable to a
    Motorola Surfboard SB5100 cable modem
    connected to the customer appearance box by the usual coaxial patch cable
    and thence via fibre to the rectangular green box in the road.

    Problem is that download speeds are vile, 0.2 Mbps instead of (towards) the expected 2 Mbps, and are about the same speeds as the upload data rate.
    So browsing is agonisingly slow, almost as slow as on a dial-up modem.
    PINGING the cable modem gets 1 ms response times BUT the occasional lost packet. The ethernet patch cable was changed, with no improvement.

    BY technical support changed the cable channel to which the equipment was connected to one which was less heavily used, but PING times from their end to the cable modem were still in the 20s and 30s of milliseconds.

    No known problems with the network 'in our area'.
    Nothing in the System or Application Event Log.
    Cable modem and PC have been powered off/on several times (in the right order!).

    I can't imagine how a PC can be responsible for packet loss on PINGs, and the patch cable has been replaced, so I suggested that it might be a good move if the cable modem were to be swapped out, and after a bit of gentle arm-twisting, an engineer is coming on Wednesday afternoon to do the deed...

    Any comments, chaps?

    Thanks

    John
    <font face="Script MT Bold"><font color=blue><big><big>John</big></big></font color=blue></font face=script>

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  2. #2
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    Re: Packet Loss on PING

    John,

    What do you mean by "occassional" packet loss?

    You really shouldn't see any of these, but losing 1 packet per thousand shouldn't cause the impact on download speeds you describe.
    What "ping" time do you get to your local router (should be < 1ms)
    What times does Tracert show to other hops on the way to the website where you measured the download speed? Is there a particular hop that adds significant time?

    StuartR

  3. #3
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    Re: Packet Loss on PING

    "Occasional packet loss" to the local cable modem was zero, one or two in the usual four packets (most commonly the first packet sent, but not consistently) with 1 ms if it actually worked. Probably on average about 20% failure, which is pretty drastic. No obvious problem in Device Manager -> the NIC.

    I didn't do any tracerts, which would have been a Good Idea. PINGs to www.bbc.co.uk were in the 10-20 ms range, when they worked...

    John
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  4. #4
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    Re: Packet Loss on PING

    20% packet loss is really serious.

    It would be worth trying
    <code>ping -n 100 gateway-address</code> (replacing gateway address with the address of the thing at the end of the Ethernet cable)
    to see if you get a consistent 20% loss of packets.

    Other than the cable or the router, it could be a faulty NIC at the computer end.

    StuartR

  5. #5
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    Re: Packet Loss on PING

    No, the packet loss on repeated PINGs for four packets appears pretty random.

    If it was a NIC problem would you not expect to see something relevant in the Event Logs? If it's that, then it's a new motherboard... (Or a new NIC card, of course...!)

    John
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  6. #6
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    Re: Packet Loss on PING

    In my experience, a failure on the NIC will not necessarily result in event log entries, it depends on the exact nature of the problem.

    If the NIC has failed then you won't need to replace the motherboard, so long as you have a free slot you could just add a new NIC card and use that, but lets wait to see if the new router fixes your problem first.

    StuartR

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    Re: Packet Loss on PING

    I've never actually heard of a NIC failing! But yes, they are nearly free now, not like in the days of the 3C509...

    The cable modem gets swapped out, one trusts, on Wednesday afternoon...

    John
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  8. #8
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    Re: Packet Loss on PING

    John, this probably isn't worth anything to you, but four or five days ago, I had the "cable guy" here for a short service call too. I was amused when he came in the door with a replacement new modem box under his arm, as if he was planning ahead... My problem was different than yours - random but short losses of connectivity. Anyway, while he was running his tests on my cable signal, the modem and so on, with his metering/test equipment, I noticed that he ran a ping on his server using ping xxx.xxx.xxx.xxx -t and I had never used that switch before. Of course, his answer was that it's a way to get more than the usual four packets.

  9. #9
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    Re: Packet Loss on PING

    Yes, I use PING -t occasionally, and PING -t nnn to act as a wait of (nnn-1) seconds in BATch files, as in
    ping -n 11 127.0.0.1 > nul
    for a wait of 10 seconds. It's pretty accurate!

    Thanks

    John
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  10. #10
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    Re: Packet Loss on PING

    Al,

    One of us is confused

    <code>ping x.y.z.a -n 50</code>
    will send 50 packets

    <code>ping x.y.z.a -w 50000</code>
    will wait up to 50 seconds for a response before timing out

    <code>ping x.y.z.a -t</code>
    will keep pinging the remote node till you typc Control-C

    StuartR

  11. #11
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    Re: Packet Loss on PING

    I dunno what you mean, Stuart. I'm not confused and only mentioned the switch in case John wasn't aware of it. He was talking about the loss of one or more packets of the "usual" four sent by an unspecified ping command. I wanted to make sure he knew that he could keep the ping going continuously with that switch to see what result he got with a stream of MORE than four packets.

  12. #12
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    Re: Packet Loss on PING

    I guess the one who was <img src=/S/confused.gif border=0 alt=confused width=15 height=20> must have been me then <img src=/S/smile.gif border=0 alt=smile width=15 height=15>

    StuartR

  13. #13
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    Re: Packet Loss on PING

    Just to wrap this thread up...

    Last week the engineer came to replace the motherboard in this six-month-old PC under the warranty, and discovered that the one he had brought didn't "quite" fit, even though it should have been a direct swapout. So his suggestion was either to have the entire PC replaced and all the software reinstalled, or to get a new NIC. And no, they wouldn't pay for the NIC!

    So I went to the alleged PC SuperStore which has originally supplied the PC to buy a new NIC -- and would you believe there was not a single one available to be bought, and no idea when they would come in? So I had to go to Staples to buy a Belkin NIC for only twice the price. This afternoon I installed it, and all is now well.

    John
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