I was conducting SkyX (Mentat) tests at NASA Goddard.
Our test configuration is over emulated "GEO-satellite" links
and the results are showing a throughput gain ratio of 10
to 100 in favor of Skyx when compared with a "vanilla" TCP
(no large windows).
The TCP throughput w/ large windows and SACK over long-fat pipes (RTT=540 msec,
OC-3 links) is good (72% of theoretical rate) at low BER (none or 1E-10)
but it degrades heavily when BER is bellow
1E-7 (only 4% of theoretical rate for BER=1E-7).
SkyX throughput doesn't degrades (only small variations) at low BER
(1E-6, 1E-5).
We plan to cooperate with another group here at NASA Goddard
for tests over real satellite.
Our tests involved the following configuration:
+----------+ TCP +---------+ SkyX +--------+
| end-host |______| |_______|unix gw |
|(receiver)| IP/ | SkyX gw | IP/ |________|
+----------+ Eth +---------+ Eth
| SkyX/IP/ATM
|
+--------+
| ADTECH | - data link emulator
+--------+
| SkyX/IP/ATM
|
+----------+ TCP +---------+ SkyX +---------+
| end host | IP | | IP | |
|(sender) |-----| |--------|unix gw |
| | Eth | Skyx gw | Eth | |
+----------+ +---------+ +---------+
The links are 100 Mbps.
The end-host machines and SkyX gateways are Linux boxes;
The 2 UNIX gateways are mapping the IP traffic to ATM;
The data link emulator (ADTECH AX/4000 ATM test system)
is used for tests of IP over ATM traffic; it is emulating
delays, BER, cell drops, burst error rates, etc.
If you are interested in more information regarding specific performance
metrics and test conditions (window size, RTTs, BERs, ttcp parameters used)
please contact me @ 301-286-2188
or Pat Gary @ 301-286-9539 ([email protected])
Marian Stagarescu - NASA GSFC/Raytheon ITSS
HPCC/HECN group
This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:52 EST