Hi-
You might want to consider how the traffic serialized from the router
into the modem. Does the circuit use a WAN protocol or does the
router bridge raw TCP/IP packets? If the router uses a WAN protocol
with a HDLC frame with mod8 window for the WAN protocol, you will
likely have some problems with efficiency on the Eutelsat Geosync
circuit. The propagation delay is likely too large to keep the
window rotating (aka, sky full of packets and not waiting for an
ack). If your router supports a larger window size or mod128, it
would be advisable to increase. A WAN protocol like X25 with LAPBE
(mod128) works OK. It also helps to use a large packet size.
Regards,
-Tom Saam
t.j.saam@ieee.org
______________________________ Reply Separator _________________________________
Subject: ftp over transparent satellite link (with 3COM-Routers)
Author: bettina.pieper@rektoramt.uni-ulm.de at PMDF
Date: 3/13/98 11:10 AM
Hello,
I am still struggling with my problem to have an efficient data-rate for
ftp over a transparent 384 kb/s satellite link:
The configuration is as follows:
PC1 - Router 1 - Sat-Modem 1 <--- EUTELSAT ---> Sat-Modem 2 - Router 2
- PC2
PC1 and 2 with Ethernet-Interface (10 Mb/s)
Router1 3COM, NetBuilderII with RS449-Interface; Software Version
7.2
Router2 3COM, NetBuilder Remote Office 227 with RS449-Interface;
Software Version 7.2
Some tests:
Test configuration 1:
PCs running OS/2 2.11; IBM TCP/IP version 2; PPP on the Router
result: ftp of the same 350 kB-File in 96 s, 6.5 s, 9.6s, 140 s, ...
that means no constant rate
Test configuration 2:
PCs running with Linux-Boot-Disks (Kernel vers. 2.0.?); PPP on the
Router
one test with TTCP with 1024 byte Packets: 23 kB/s = 50% of the max data
rate
(I will keep on testing with the Linux config.)
Any idea for "the best" configuration of the Routers - maybe as a
Bridge, compression y/n and which one (Per Packet or History), etc. and
maybe another ftp-Software.
I would appreciate help very much.
Bettina Pieper
--
----------------------------------------------------------------
University of Ulm, DR-1
Dr. Bettina Pieper
E.C./R&D Management in the President's Office
D-89069 Ulm
phone: +49-731-50-22010/2011
fax: +49-731-50-22016
e-mail: bettina.pieper@rektoramt.uni-ulm.de
http://www.uni-ulm.de
Received: from 192.168.190.1 by ALPHA.CORP.SCIATL.COM (PMDF V4.3-13 #7203) id <01IUMBKB8T1S000WJ3@ALPHA.CORP.SCIATL.COM>; Fri, 13 Mar 1998 13:42:35 -0500 (EST) Received: from [129.4.51.2] by gatekeeper.sciatl.com for <Tom.Saam@Sciatl.COM> id NAA24374; Fri Mar 13 13:49:03 1998 Received: by achtung.sp.trw.com (4.1/SMI-4.1) id AA12399; Fri, 13 Mar 98 06:54:26 PST Received: from mizar.rz.uni-ulm.de by achtung.sp.trw.com (4.1/SMI-4.1) id AA12394; Fri, 13 Mar 98 06:54:19 PST Received: by mizar.rz.uni-ulm.de with Smail id m0yDVwb-000XiUC; Fri, 13 Mar 98 16:00 MET Received: from birgit.rektoramt.uni-ulm.de(134.60.45.15), claiming to be "rektoramt.uni-ulm.de" via SMTP by mizar.rz.uni-ulm.de, id smtpdAAA0J25pi; Fri Mar 13 16:00:14 1998 Date: Fri, 13 Mar 1998 16:10:29 +0000 From: "Dr. Bettina Pieper" <bettina.pieper@rektoramt.uni-ulm.de> Subject: ftp over transparent satellite link (with 3COM-Routers) Sender: owner-tcp-over-satellite@achtung.sp.trw.com Message-id: <35095A74.2E2890C6@rektoramt.uni-ulm.de> Organization: University of Ulm X-Envelope-to: "Saam, Tom%SA-MEL-420"@ccmail.corp.sciatl.com MIME-version: 1.0 X-Mailer: Mozilla 4.03 [en] (WinNT; I) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Precedence: bulk
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