2.7.15 TCP Over Satellite (tcpsat)

NOTE: This charter is a snapshot of the 42nd IETF Meeting in Chicago, Illinois. It may now be out-of-date. Last Modified: 18-Aug-98


Aaron Falk <adfalk@mail.hac.com>

Transport Area Director(s):

Scott Bradner <sob@harvard.edu>
Vern Paxson <vern@ee.lbl.gov>

Transport Area Advisor:

Vern Paxson <vern@ee.lbl.gov>

Mailing Lists:

General Discussion:tcpsat@lerc.nasa.gov
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Archive: http://tcpsat.lerc.nasa.gov/tcpsat/mail.html

Description of Working Group:

Satellites are being used to extend the Global Internet geographically and will be more ubiquitous in the next decade with the deployment of several proposed services capable of providing greater than T1 access to individual users anywhere in the world.

Yet, satellite links have a unique combination of characteristics that can affect the throughput of TCP traffic. Because of the high-bandwidth delay product, slow start and congestion control algorithms behave much differently when the path includes a satellite link than exclusively terrestrial ones.

The TCP over Satellite Working Group shall produce an informational RFC which describes the issues affecting TCP throughput over satellite links. It identifies the domains in which each issue applies, including network topology, satellite orbit (LEO, MEO, GEO), and link rates; fixes, both protocol and implementation, that ameliorate reduced throughput; and areas for further research. The purpose of including this information is to direct the research community to the areas in which show promise, not to perform the research or even advocate the results.


The scope of this working group will include consideration of the following for inclusion in the Informational RFC:

o Transport layer issues affecting TCP over satellite links o Existing TCP options o Compliant implementations which have some known improved performance over satellite links o Recommendation of well understood protocol changes o Identification of protocol changes that are potentially promising but require more further investigation in order to be well understood


The working group will consider in depth security issues that are relevant, describing risks and indicating how they may be addressed.

Goals and Milestones:

Jul 97


Post first Internet-Draft.

Aug 97


Meet at Munich IETF to review Internet-Draft.

Dec 97


Meet at DC IETF tyo achieve consensus on final version of Internet-Draft.

Jan 98


Submit Internet-Draft to IESG for consideration as an Informational RFC.


No Request For Comments

Current Meeting Report

TCPSAT Summary:

The TCP over Satellite group met on Wednesday, August 26th, at 3pm.
Aaron Falk, WG Chair, presented status showing the following:

1) The Internet Draft "Enhancing TCP Over Satellite Channels using Standard Mechanisms
" is nearly done and should be ready to go to last call on the list. This document will be
slated for a BCP track.

2) The Internet Draft "Ongoing TCP Research Related to Satellites" is still incomplete but
there are authors assigned for the unwritten sections. The schedule is to send out a last-
call-ready draft before the next IETF with last call to follow in January 99.

3) TCPSAT should have it's last meeting at IETF-43 in Orlando.

4) A discussion on TCP Spoofing was held following the last TCPSAT meeting at the LA
IETF. A mail list and web site were created but little traffic ensued. Next steps, for those
interested in seeing this activity continue, would be to produce a short I-D defining terms
and architectures and a second I-D discussing spoofing mechanisms and risks. The web
site is http:tcppep.lerc.nasa.gov/tcppep.

Mark Allman, document editor, presented a brief summary of comments recieved on the two
drafts and changes made to accomodated them. A suggestion was made to allow input from
non-assigned authors on the-research-issues- I-D so that completion of the document did not
rely solely on the assigned authors.

The issue was raised as to whether issues pertaining to TCP over ATM (ABR) over satellite
should be included in the research issues draft. The consensus among the chair, editor, and
ADs was that unless specific TCP mechanisms were at issue, it was out of scope for the
document. The decision was made (after the meeting) for the author to summarize the issues
he felt were relevant and email the summary to the chair, editors, and ADs for further review.

Dave Beering, Sterling Software, presented results of a NASA Advanced Communications
Technology Satellite Experiments 118x. These experiements showed 97% utilization of a
OC-12 satellite link using a single TCP connection and Solaris 2.6 w/patch, Solaris 2.7,
Windows 4, and Windows 5.

Eric Travis, JPL, presented a summary of the InterPlaNet brainstorming going on at JPL
w/Vint Cerf's help to extend the Internet to farther than Earth orbit. This activity is unrelated
to TCPSAT but was thought to be of interest to the audience.


None received.

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