Re: AX25 UTILS and PTC-II

From: Terry Dawson (lmo@ringpower.com)
Date: Mon Jan 21 2002 - 12:24:03 EET

  • Next message: Jonathan NAYLOR: "Re: AX25 UTILS and PTC-II"

    Wilbert Knol wrote:

    > Yes, I agree that it it would be best to have the PTC-II controlled directly
    > by kernel-AX25. Until someone writes a Linux device driver for extended-
    > hostmode, this is not possible. I don't think there is a problem. The
    > extended-hostmode protocol is public. In fact, some of the code could be
    > borrowed from TNT.

    I struggled with thinking about ways to make the hostmode interface talk to the
      kernel sensibly and the best solution I could think of is the one I ended up
    implementing.. when looking for analogs of hostmode channels, the best I could
    find was the concept of 'connection' in AX.25, NetRom or ROSE. The task became
    one of taking a channel and translating it into a connection. Fairly simple if
    you only want to deal with one direction, a little more tricky if you want
    bidirectional capability. In the end ROSE was appropriate because it seperated
    the notion of 'callsign' from that of address. This was especially convenient
    because I wanted a way to address ports, but to also supply a callsign that
    that port should configure itself as. ROSE made this easy.

    > The comment on IP over HF PACTOR was made in jest. However, it may
    > be feasable with the faster (and wider) PACTOR-3.

    So long as the initial round trip time parameter for TCP were kept very very
    high it could be made to work, but I think the IP overhead would feel tragic
    over such a low speed link. Header compression would go some of the way to
    relieving that.

    > Anyway, I am intrigued by Terry's solution for Rose, something I don't
    > know much about. Also Tomi's NEWQPSK, capable of carrying IP. So
    > many things to try...and not enough time!!

    I'm only equipped for 20m PACTOR operation, do you operate there? Part of the
    reason I've not really worked on it much is that I've had noone to test it
    with. Could you help with on-air tests do you think?

    regards
    Terry

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