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PA2AGA > TCPDIG 14.01.98 02:05l 132 Lines 4951 Bytes #-10102 (0) @ EU
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From: pa2aga
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Subject: TCP-Group Digest 98/6B
X-BBS-Msg-Type: B
stack supports it. Why? Medium- and high speed NETROM interlinks
still suffer from unneccessary congestions on L2.
Of cause higher maxframe values only make sense in case we don't have
to re-transmit a complete chain of 40 256-byte-packets because one
frame in the middle got lost. That's why we need an intelligent frame
acknowledge technique, some type of ack frame permitting operations
like "RR 4-12, 14-25, 28-41" (Ack'ing Frames 4 to 12, 14 to 25 and 28
to 41 because 13, 26 and 27 got lost).
- Protocol overhead reduction by header compression
Address fields in AX.25 (HDLC) Headers are subject of consumption of
an overproportional amount of space. Protocol extensions like
FlexNet's AX25 header compression allow the reduction of this type
of overhead to a minimum.
- Data forwarding should be dealt with on L3, the IP layer, enabling
a congested router to apply countermeasures like dropping IP
frames / sending ICMP source quenches (RFC-896!!!) or recomputing
data paths in order to redirect traffic to less-congested links
using routing protocols.
- Option handling
The new protocol should be open for future extensions. Possible
options (window sizes, L3 protocol types, ...) could be negotiated on
link setup. It's a shame that "vanilla ax25 users" have to send an
I-Frame to let the remote host understand that there's no L3 protocol
in use. Also you could play with LZW compression of data payload or
encryption. By the way, it's time to make the PID (L3 Protocol
Identifier) fields 2 bytes wide and implement a more flexible method
of fragmenting frames on L2. Maximum packet size should be raised,
and negotiated on link setup, too.
- Channel access
We definetly need something TDMA-like to get rid of the
"hidden-station"-problem on point-to-mp links (user entry channels),
and it's got to be in software. Most hardware implementations I can
think of are too expensive to implement. OPTIMA is without doubt a
step to the right direction.
Anybody else?
-- Jens
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Date: Mon, 12 Jan 1998 23:29:18 +0900 (JST)
From: noriton@netwk.ntt-at.co.jp (Norito NEMOTO)
Subject: TCP/IP over radio
at <34B93C18.3D423F41@perf.no.itg.telecom.com.au>
terry@perf.no.itg.telstra.com.au wrote
Thank you for your reply.
>> Norito NEMOTO wrote:
>> > Please expect next DCC.
>> > we are going to attend DCC meeting with many paper;-)
>> My only response is a series of questions:
>> Where can I get more information? (What is DCC?)
It's Digital Comunication Conference, ARRL and TAPR sponsored.
If you want to get detail, see http://www.tapr.org/
>> > 800kbps MSK or 808kbps SS physical modem (faster is better)
>> > hardware Vitabi FEC
>> > used MACA, canceled hidden terminal.
>> > We made 808kbps wide area link system at 2.4GHz SS.
>> > Alredy tested 20km trancefar completly.
>> > #Of course, we welcome to discuss about this proposal.
>> Do you have an estimate of how much what you are building would
>> cost ? in kit form ? in production form ?
We started release test version
(808kbps 2.4GHz SS tranver used, CSMA, block FEC, fixed routing,
and needed other's linux or FreeBSD computer.)
Ether-net interface(KIT) : about 18000JPY (140USD?)
SS RF Trancever. (PRODUCTION) : 60000JPY (450USD)
If you want these set, we can release now.
But software's release maybe Feb. or Mar.
But final all-in-one system, I think 120000JPY (900USD) or cheper.
>> Do you have any contacts in any of the amateur radio manufacturing
>> companies that might be interested in mass producing it ?
SS Trancever is some radio manufacturing made.
We ordered to change for amateur radio band.
And we are going to meet TAPR member for fixed Ether-net interface's
spesfications and how development.
>> Will you keep us updated on your progress ?
Yes!! Of course.
And please give us mary suggestion.
------------------------------------------------- o o
Norito Nemoto / JH1FBM Nakano-city, Tokyo,Japan \_(((_/
/ \
Packet Radio User's Group / PRUG96 project ___/ n n \__
in charge of FEC chip, MACA, and FBPASS. ( o )
\__ __/_
E-mail noriton@netwk.ntt-at.co.jp \ ^ ^ ^ \_/ |
WWW http://www.nemoto.com/ \ ^ ^ (
Network Applique'tion Laboratory Mascot "TOCKALI kun" \______/\_|
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End of TCP-Group Digest V98 #6
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