[comm]Fyi: VLBA Network Bandwidth Comments

[Gareth Hunt]

Guys,

Here is a note from Paul Rhodes containing comments from two VLBA site techs
and my response to one of them.  As I said in my response, there seems to be a
clear need for higher bandwidth connection to the VLBA sites.

Cheers,
Gareth.
------- start of forwarded message (RFC 934 encapsulation) -------
From: Paul Rhodes <prhodes at aoc.nrao.edu>
To: ghunt at NRAO.EDU
Subject: VLBA Network Bandwidth Comments
Date: Mon, 07 Jan 2002 09:58:12 -0700

Gareth,

You asked for comments about the VLBA connectivity so I inquired to see
if anyone was having any problems.  Here are the results from two of the
Intranet connected stations. It appears that most of the Stations have
learned to "be patient" and they do not have any other experiences to
compare their service at the stations.  When I visit the stations I
notice a severe slow down from my connection experience at the AOC. 


North Liberty  Bandwidth For VLBA Sites:    Mike Burgert 12-10-01

There are many reasons to re-evaluate the Internet connections at the
VLBA stations. Most sites are connected via 10-year-old technology, and
huge price/performance gains can be realized. 
Here at the North Liberty VLBA station, our average transfer rate is
less than 3kB/sec. This is noticeably slower than a 56k dial up modem
connection. I have installed (at my own expense) an ADSL modem and
router/firewall to the computer I use here at the station. I am not
connected to the NRAO intranet. The speed and reliability of this
connection is excellent. Unfortunately, I am unable to access all of the
NRAO servers due to NRAO firewalls.

Transfer Rate Comparison:

I did a comparison of a few things that I would consider common
activities for a station technician using the Internet. The first
example is using VLCj to monitor the health of the site's cryogenics, in
the second example, I went to a website to research an electronic
component for a NRAO project I am working on. When doing design work, it
is necessary to look at datasheets for several I.C.s from several
different manufactures. Most datasheets are in Adobe .pdf format, and a
20-page document is about 500KB. 

1. Connect to VLCj 			DSL=3-4 sec.		T-1=10 sec.

2. Create a graph of cryo
temperatures of 10 receivers for 
144 hours.				DSL=4 sec.		T-1=13 sec

3. Go to Maxim I.C.s 
Datasheet search page			DSL=3 sec.		T-1=20 sec

4. Download a Datasheet
for an IC. 648KB			DSL=10 sec.		T-1=01:45 mm:ss

5. Download a Radar Image		DSL= 1-2 sec.		T-1=14 sec.

6. Transfer of a site camera image	DSL = <20 sec.	T-1 = 45 sec.to 1 min
to the AOC. (Aprox. 300KB)

7. MainSaver: (better pack a lunch!) Using Citrix meta Frame on Zaphod. 
Mainsaver is not DSL accessible due to firewalls, Very Slow!

The ADSL connection is about 10 times faster than the T-1 connection.
The T-1 speeds listed are with one user on the T-1, with no site camera
connected. When the site camera is operating on the T-1, the data
transfer comes to a screeching halt for about 1 minute, every 5 minutes
of the day 24/7! 

Some may argue that the VLBA sites do not "need" any more speed than
they already have. As far as the functionality of the site, this is
probably true. But, technology has come a long way, and ignoring the
new, and better connectivity optionns my have a greater effect in the
future. 

Pricing to upgrade to ADSL at North Liberty

Basic Service:	 	384K downstream 128K upstream		 $39.95 per month
Static I.P. Address					         $20.00 per month

Hardware Requirements:

Alcatel Speed Touch Modem					$125.00 (on site N/C)
LinkSys BEFSR41 4 port Router with Firewall and DHCP		$125.00 (on site
N/C)
Category 5 network cable and connectors				$20.00

The ADSL service here is provided by the local phone cooperative South
Slope www.southslope.com  I have been using their ADSL service for about
1 year now, and I have never had a single outage. The company has
implemented an "ATM Cloud" (Asynchronous Transfer Mode) making ADSL
extremely reliable. 

Should N.R.A.O. decide to give this service a try, I would be glad to
assist in the hardware installation and configuration. In fact, I'd even
donate my hardware if North Liberty could be used as a test site! So,
the total cost to NRAO would be $59.95 per month for static I.P. with
the rest of the station computers assigned IP addresses via the router.
I realize not all sites have access to broadband… But, if a site has
access, and it is of better performance, and the operating cost is less,
WHY NOT?!

P.C. to P.C. Internet phones, and video conferencing could also help cut
phone costs! (Instead of paying for tech meeting conference calls…)


Owens Valley   Jim brown's comments to Marie Glendenning  10-3-01


Hi Marie,
         Yesterday you asked me to send you an email describing any
difficulties I've experienced using Mainsaver.  I performed the
Mainsaver upgrade last March 14 on the site NT machine.  Since then, it
has displayed occasional episodes of severely decreased performance.  At
times the program would operate so slowly that I could sit back and
watch it slowly constructing a page piece by piece.  Using the mouse to
perform simple operations was even slower and uncertain.  On this end,
it didn't matter that I closed out of all other running programs to free
up the RAM.  On the other (Citrix) end, the connection to the server
shows no less than 22 running programs in the system tray each time I
connect.  At its worst, Mainsaver would hang and be totally
unresponsive.  This computer's Windows Task Manager would report it as
"not responding" and I would have to use the "End Task" feature to close
out and start over.  That's something I never had to do before the
upgrade. This could be a problem with the network, the server, or simply
the number of users connected to the Mainsaver database at the same
time.  I understand the Mainsaver upgrade has passed its tests at
another location.  The performance issue is tolerable as long as I can
finally use the program to get the job done.  Yesterday, I couldn't even
connect with the server.  I tried several times, always getting the same
message: "Unable to find the path to the Citrix server".  I finally
asked Operations whether others were having the same problem.  They
weren't.  I don't know what was wrong with it.  Today I was able to
connect and use Mainsaver several times, and it now operates as well as
it ever did.  Thank you for your help.

Jim


**********************************************************************
Paul J. Rhodes                                 Array Operations Center 
VLBA Field Group Leader                        P.O. Box O 
National Radio Astronomy Observatory           Socorro, NM 87801
www.nrao.edu                                   505-835-7256 
**********************************************************************
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------- start of forwarded message (RFC 934 encapsulation) -------
From: Gareth Hunt <ghunt at NRAO.EDU>
To: Mike Burgert <mburgert at aoc.nrao.edu>
Cc: Paul Rhodes <prhodes at aoc.nrao.edu>
Subject: Re: VLBA Network Bandwidth Comments
Date: Mon, 7 Jan 2002 19:04:42 -0500 (EST)

Mike,

Thanks for your useful input on the North Liberty situation.  First let me
correct a couple of misunderstandings.

MB> There are many reasons to re-evaluate the Internet connections at the
MB> VLBA stations. Most sites are connected via 10-year-old technology, and
MB> huge price/performance gains can be realized. 

No, they are not connected by old technology.  What we are limited by is the
detailed configuration.  The connection uses frame relay, and the underlying
protocol is ATM.  Only for cost savings is the NL site configured for T1
service at all.  At the time of installation, the Monthly Recurring Cost (MRC)
for T1 in NL was cheaper than an analog 64k/56k circuit!  However, it is
provisioned just to use one 56k channel of the T1 frame, and that has a
Committed Information Rate (CIR) of just 16kbps.  We do see bursts up to 400%
of the CIR on the circuits to the VLBA antennas, so the full channel is used
upon occasion.

MB> Here at the North Liberty VLBA station, our average transfer rate is
MB> less than 3kB/sec.

Once a program link is established, the data rate should be able to burst as
high as 7kB/sec.  However, short transactions will be limited by the
initial handshaking.

MB> This is noticeably slower than a 56k dial up modem.

It shouldn't be.

MB> I have installed (at my own expense) an ADSL modem and
MB> router/firewall to the computer I use here at the station.

MB> Transfer Rate Comparison:

MB> I did a comparison of a few things that I would consider common
MB> activities for a station technician using the Internet.  <etc.>

MB> The ADSL connection is about 10 times faster than the T-1 connection.

For reasons given above, the improvements that you see are not a surprise.
If you have 384k on the DSL link, this is 8x the NRAO connection.

MB> Pricing to upgrade to ADSL at North Liberty

MB> Basic Service:       384K downstream 128K upstream           $39.95 per month
MB> Static I.P. Address                                          $20.00 per month

Now this is impressive.  We are presently paying $300 per month for the
16k/64k/T1 service.  This is about twice what we were paying under the contract
in 2000.  When we renegotiate, we hope for a substantial reduction back to the
original level, but that still probably will not be as low as your figure.

MB> The ADSL service here is provided by the local phone cooperative South
MB> Slope www.southslope.com  I have been using their ADSL service for about
MB> 1 year now, and I have never had a single outage. The company has
MB> implemented an "ATM Cloud" (Asynchronous Transfer Mode) making ADSL
MB> extremely reliable. 

As you say ATM is extremely reliable.  For all of our frame relay connections,
we only had to make 6-7 problem calls last year.

MB> I realize not all sites have access to broadband… But, if a site has
MB> access, and it is of better performance, and the operating cost is less,
MB> WHY NOT?!

My answer to that is centralized service.  Before we had the frame relay
service, we had to monitor each connection separately.  It was an operational
nightmare - we essentially had one person on staff who did nothing else.  With
a single contract, we have a single number to call 24x7 for all problems.  The
contractor (AT&T in this case) also deals with the local phone companies.  In a
few instances, AT&T has even called us and informed us of problems.

I agree that you and your local ISP would be a perfect contact for NL, but what
happens in the middle of the night, on weekends, or when you're on vacation?
In our present case, we call a single number and the service call proceeds from
there.

MB> Some may argue that the VLBA sites do not "need" any more speed than
MB> they already have. As far as the functionality of the site, this is
MB> probably true. But, technology has come a long way, and ignoring the
MB> new, and better connectivity optionns my have a greater effect in the
MB> future. 

I think that there is a clearly demonstrated need for all of the VLBA sites to
have improved access.  Your response indicates how frustrating it must be for
all of the VLBA site techs, even though most of them have resigned themselves
to the present connection speed.

Higher speed connection to all sites comes at a cost, but we intend to pursue
this vigorously in our planned Request For Proposals (RFP).

MB> P.C. to P.C. Internet phones, and video conferencing could also help cut
MB> phone costs! (Instead of paying for tech meeting conference calls…)

Actually not.  The VLBA site phones are now being billed at $0.05 per minute
including applicable taxes.  If you have four 1 hour conferences per month,
this comes only to $12.  The cost of having the phone in the first place is
probably $30 including taxes.

However, you are on the right track.  If the RFP allows us to increase the
access bandwidth to the VLBA antennas, we will also look into Voice over IP
(VoIP) phones for the sites.  In that case, we could have local Socorro numbers
at each of the sites.  We can also look at PC video conferencing.

Again, thanks for your constructive comments.

Cheers,
Gareth.
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