[Sis-csi] 2:30 Eastern it is -- IDEA VxWorks info

Thu Feb 1 15:09:00 EST 2007

Wow, that's great info!

OK, so those machines top out somewhere between 15k and 30k packets
(VCDU frames)/s and can handle at least 132Mbps through.  To a rough
order approximation, let's say that any IP QoS (marking, cbq, etc.) we
might want to do is about as compute-intensive as whatever VCDU
processing is done.  In any case, that kinkd of uplink rate is waayyyy
over current envisioned uplink rates, and probably close to the limits
of the RF system (as I feared it would be).

VxWorks images are determined by the set of features enabled, but I
suspect that most run around a few tens of Megabytes, so even a 10Mbps
uplink rate should cover a full (base) software reload in under a
minute.

Since there's almost surely a trade between speed and
reliability/correctness, do we foresee any kind of BER requirement we'd
like to see on these high-rate uplinks?

I think I should work with Greg to see what the next 'ceiling' above
10Mbps might be in terms of coding / framing.  I suspect that once we
can do 10Mbps up then (from the baseband processing standpoint, not RF)
15, 20, or even 40 might not be too hard.

		--keith

-----Original Message-----
From: Schneider, Larry [mailto:larry.schneider at nasa.gov] 
Sent: Monday, January 29, 2007 6:31 PM
To: Scott, Keith L.; sis-csi at mailman.ccsds.org
Subject: RE: [Sis-csi] 2:30 Eastern it is -- IDEA VxWorks info

We know Linux well but are not VxWorks experts. If someone has some
commands we could run or tests we could perform within reason we'd be
glad to.

The VxWorks systems we have are TSI FDPs. They are  about 4 years old.
We think they are ~ 300 MHz. We recall 
discussions about upgrading them to 433 MHz though that never happened.

There are a total of 21 of them located at MSFC (6), JSC (3), WSC (6) ,
and a couple of support facilities (2). We have four in our lab.

The systems process the ISS Ku-band 150 mb/s downlink as well as the
S-band downlink.

The systems process 15,000 1100 byte VCDU frames / second in and out.
We
demonstrated the systems can not process 30,000 1100 byte VCDU frames /
second in and out though we didn't try to probe any further.

We also demonstrated that they can't record and distribute 15,000 1100
byte VCDU frames at the same time.

-----Original Message-----
From: sis-csi-bounces at mailman.ccsds.org
[mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Scott, Keith L.
Sent: Thursday, January 25, 2007 2:42 PM
To: Scott, Keith L.; sis-csi at mailman.ccsds.org
Subject: RE: [Sis-csi] 2:30 Eastern it is

People I heard on the call:
	Keith Scott
	Howie
	Keith H.
	Scott B.
	Ed Criscuolo
	Will Ivancic
	Larry Schneider
	Ed Greenberg

** Request from the high-rate uplink WG

Current TDRSS uplink rate is 25Mbps (Dave?) There seemeed to be some
confusion about what the real rate(s) were:
	S-band is 2-4 mbps
	Ku ~3Mbps up and down

Scott: to estimate the required uplink data rate, find out the maximum
rate at which you can forward packets, and use that.  If the first
spacecraft on orbit has to serve 3 others or 60 others, doesn't matter,
they get what they get but at least we'll be able to get the data up as
fast as we can forward it.  For this exercise, assume a dedicated
processor for packet handling.  Keith H. notes that several years ago
i386 class machines could saturate a 10Mbps Ethernet, so even rad hard
things nowadays should be able to do that.

What rates can VxWorks forward at over the past N years?
VxWorks -- how fast can the network stack forward.
Scott and/or flight software people at Goddard may have some VxWorks
machines.
Larry Schneider has a lot of VxWorks machines to handle the ISS
high-rate uplink
	VxWorks expert is off this week but email out questions to
Larry
(to give to
	Alex).

Ed -- driver for uplink may be HD uplink video (~5mbps) Cap everything
by about 30-50Mbps because we don't think uplink radios can do more.

Will sent email
"What is 'uplink'?"

		--keith

-----Original Message-----
From: sis-csi-bounces at mailman.ccsds.org
[mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Scott, Keith L.
Sent: Thursday, January 25, 2007 12:35 PM
To: sis-csi at mailman.ccsds.org
Subject: [Sis-csi] 2:30 Eastern it is

Ok, we're on for 11:30 pacific, 1:30 central, 2:30 eastern on
Thursdays, starting today.

Phone Number:
	703 983 6338 (x31550) in Washington
	781-271-6338 (x16338) in Bedford 
	866-648-7367 (866-MITRE-MP) Toll Free

Meeting ID: 55555

Today's Agenda:
	Recap from Colorado Springs Meeting
	Request for requirements info from High-Rate Uplink WG
	Red Book 1 Items:
		Collect information and distribute
			GPM (Jane)
			CANDOS (Dave/Keith H.)
			SNIS (Dave)
			Shuttle&ISS (Larry)
			Surrey satellite (Loyd/Will)
		Mash these against requirements
		From the 'assumptions' slide, list possible solutions
to each of the requirements
		Downselect possible solutions
		Assign people to write text
		Publish book

		--keith

-----Original Message-----
From: sis-csi-bounces at mailman.ccsds.org
[mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Scott, Keith L.
Sent: Thursday, January 25, 2007 9:34 AM
To: sis-csi at mailman.ccsds.org
Cc: Greg.J.Kazz at jpl.nasa.gov
Subject: [Sis-csi] Telecon scheduling and request for requirements

========== Telecon scheduling

I apologize for this but we're going to need to reschedule our weekly
telecons, starting with today's.  Hopefully this will be the last time
we'll have to do this for a while.  I'll start off by proposing one
hour earlier on Thursdays (11:30 pacific, 1:30 central, 2:30 eastern).
Please let me know if this works for you and, if not, what would.  If
we can't come to consensus quickly we'll wave off this week's telecon,
but please see below on a request for requirements from the High Rate
Uplink WG in SLS; I'd like to hash this out over email and get them an
answer by next week.

========== Request for Requirements from High-Rate Uplink WG

Following up from the Colorado Springs meetings, we've received a
request for requirements from the High Rate Uplink WG (CWE at
http://public.ccsds.org/sites/cwe/sls-hru/default.aspx?RootFolder=%2fsi
tes%2fcwe%2fsls%2dhru%2fPublic%2fCharters&View=%7bED7A93D1%2d1BB1%2d403
3%2d8432%2dD7382F71947D%7d).  In particular they want to know what
kinds of uplink rates the cislunar architecture would require.  I think
that our DOWNLINK requirements should at least cover current shuttle
and station rates of ~150Mbps, but I don't think we require full
symmetry on the uplink.

The largest driver for the uplink rate might be crew accommodation of
live HDTV events, which would be on the order of 5-10Mbps, if they were
actually provided.  If we had that then we should be able to cover most
or all of the operational uplink traffic in the margin!  :)  Just as
another point of reference, 150Mbps of TCP downlink would require
~2Mbps of TCP ACK traffic.  We also need to remember that in a
networked world such as we've proposed, one uplink may be serving
several spacecraft.

In any case, we need to provide them with a number that:
	1) Is large enough to cover our requirements for a reasonable
amount of time
	2) Is not so large that they roll on the floor laughing at us

Regardless of the rate requirement, RFC3819 (Advice for Internet
Subnetwork Designers) and maybe rfcs RFC3155 (End-to-end Performance
Implications of Links with Errors) and RFC3366 (Advice to link
designers on link Automatic Repeat reQuest (ARQ)) seem relevant.

		--keith

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