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  1. #16
    Super Moderator BATcher's Avatar
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    An interesting observation for you!
    When using PING 8.8.8.8 -f -l nnnn
    for values of nnnn near 1472 (1500 - 28 bytes for headers) I get:
    nnnn is 1474 or above - buffer fragments
    nnnn is 1446 to 1472 - PING times out
    nnnn is 1444 or below - expected response from PING

    How could this be explained?
    BATcher

    Mission: identify what we do best and find more ways of doing less of it better

  2. #17
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    Because of the distance I'm from the exchange, when I first started with TalkTalk I bought a Billion Bipac 7800N to replace the ISP supplied door stops.

    It's default setting was 1492 and that complained when I set that to 1500 as I wanted to see what TCP Optimizer would give.

    Anyway, I just set the adapters to 1492 to match and it seemed okay, although for general browsing it would probably make little difference.

    I suppose it could make a slight difference to the Latency for gamers, but they usually just asked TT to change their profile from Interleaved to Fast Path and usually increasing the SNRM from 6dB to 9dB to help with the stability.

  3. #18
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    Quote Originally Posted by BATcher View Post
    An interesting observation for you!
    When using PING 8.8.8.8 -f -l nnnn
    for values of nnnn near 1472 (1500 - 28 bytes for headers) I get:
    nnnn is 1474 or above - buffer fragments
    nnnn is 1446 to 1472 - PING times out
    nnnn is 1444 or below - expected response from PING

    How could this be explained?
    The 1474 will take that above 1500 so will need to be fragmented.

    These are what I got -

    Microsoft Windows [Version 10.0.14393]
    (c) 2016 Microsoft Corporation. All rights reserved.

    C:\WINDOWS\system32>ping 8.8.8.8 -f -l 1472

    Pinging 8.8.8.8 with 1472 bytes of data:
    Reply from 8.8.8.8: bytes=1472 time=26ms TTL=57
    Reply from 8.8.8.8: bytes=1472 time=23ms TTL=57
    Reply from 8.8.8.8: bytes=1472 time=25ms TTL=57
    Reply from 8.8.8.8: bytes=1472 time=23ms TTL=57

    Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 23ms, Maximum = 26ms, Average = 24ms

    C:\WINDOWS\system32>ping 8.8.8.8 -f -l 1474

    Pinging 8.8.8.8 with 1474 bytes of data:
    Packet needs to be fragmented but DF set.
    Packet needs to be fragmented but DF set.
    Packet needs to be fragmented but DF set.
    Packet needs to be fragmented but DF set.

    Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

    C:\WINDOWS\system32>ping 8.8.8.8 -f -l 1446

    Pinging 8.8.8.8 with 1446 bytes of data:
    Reply from 8.8.8.8: bytes=1446 time=24ms TTL=57
    Reply from 8.8.8.8: bytes=1446 time=29ms TTL=57
    Reply from 8.8.8.8: bytes=1446 time=23ms TTL=57
    Reply from 8.8.8.8: bytes=1446 time=28ms TTL=57

    Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 23ms, Maximum = 29ms, Average = 26ms

    C:\WINDOWS\system32>ping 8.8.8.8 -f -l 1400

    Pinging 8.8.8.8 with 1400 bytes of data:
    Reply from 8.8.8.8: bytes=1400 time=24ms TTL=57
    Reply from 8.8.8.8: bytes=1400 time=23ms TTL=57
    Reply from 8.8.8.8: bytes=1400 time=24ms TTL=57
    Reply from 8.8.8.8: bytes=1400 time=23ms TTL=57

    Ping statistics for 8.8.8.8:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 23ms, Maximum = 24ms, Average = 23ms

    C:\WINDOWS\system32>

  4. #19
    Super Moderator BATcher's Avatar
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    Interesting...
    BATcher

    Mission: identify what we do best and find more ways of doing less of it better

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