modem connections

in Genius Bar edited January 2014
i hav an ibook 600, 384ram running OS X10.2.1

my modem dialup connection is failing of late and keep showing thr other side has terminated the connection. My windows computer have no such problem.

i read some past threads and the following are recommended:

1) switch modem configurations to v34 or v94

2) remove TCP compression heading and PPP echo packets

What does all this mean? will these work? are there other methods?

pls advice.


  • Reply 1 of 3
    der kopfder kopf Posts: 2,275member
    I appear to have the same computer as you, and I have to say I thought Jaguar greatly improved the dial-up connection.

    Anyway, the modem script v34 procures a lower bandwidth by default, and hence should cause less errors. (it uses less of the available bandwidth - analog phone: 56OOO bps, v34 : 34000bps, and so is less error-prone). Change this in System Preferences > Network (show: Internal Modem) > Modem > Modem

    The other things: my best guess is that the modem is very good at screwing up your connection because it acts self-righteous when allowed to compress headers and correct errors. The TCP protocol is by nature self-correcting (i.e. it has mechanisms to see whether or not a specific packet has arrived and if the packet is or is not corrupted: if so, a request is sent to resend the packet.)

    It probably is so that the modem, after too many false/corrupted packets, decides that the connection is too unstable to be maintained.
  • Reply 2 of 3
    stunnedstunned Posts: 1,096member
    would changing to v34 slow down my connection speed and make internet surfing and downloads slower??
  • Reply 3 of 3
    Yes, it won't attempt to connect any faster than 34kbps, as opposed to the 56kps theoretical maximum. In theory this should be a more stable connection, as you're not trying to use the maximum bandwidth on the line: depending how bad your disconnect problem is, this may in fact prove more useful to you.

    As for TCP Header Compression and Echo Packets, turning the first one off will mean that there's more of the available bandwidth being used for TCP/IP house-keeping, possibly to the benefit of connection stability. Conversely, turning the second one off will free up bandwidth, but at the expense of connection stability.

    Apple built-in modems are notoriously finicky about line quality, so it might be worth having a chat with your service provider and seeing if they've had any problems. If they've upgraded to v.92 compliant modems at their end, you may see better results, but the main difference between v.90 and v.92 is around the way the connection is established, rather than how it's maintained during transfer.

    Der Kopf, TCP is error-correcting, but we're dealing with TCP/IP over PPP here, which adds an extra level to play with: dropped packets and a lack of handshakes would suggest a failed connection, rather than corrupted packets.
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