I also just got done doing a week long study on CIFS over satellite and
found that at about 150 ms RTT, performance degradates drastically
regardless of bandwidth. TCP window sizes make little difference. It is a
problem in block size negotiation for CIFS and the use of only one
outstanding request at any one time. There is also a patch needed for NT
servers to prevent premature TCP timeout retransmissions which prevent the
TCP congestion window from ever becoming stable.
Greg
At 04:52 PM 11/10/99 -0500, Graham Fennie wrote:
>Greg,
>
>Absolutely correct... Since MetaFrame simulates a 'realtime' client /
server environment it is *extremely* sensitive to latency - although its
bandwidth requirements are fairly low (33-56 kbits / sec).
>
>Also, MetaFrame should be avoided in graphics intensive applications such
as Photoshop, PageMaker, etc. The increased graphics requirements of these
applications can quickly consume 192+ kbits or more.
>
>-Graham
>
>
>Graham A. Fennie
>Systems Engineer
>Western NY Computing Systems, Inc.
>(716) 381-4120 x7334
>[email protected]
>
>>>> "Gregory D. Otto" <[email protected]> 11/10/1999 4:36:40 PM >>>
>I have found that if you have latencies approaching 200 ms, Citrix users
>will complain of unacceptable performance.
>
>
>At 12:25 PM 11/10/99 -0500, Graham Fennie wrote:
>>Citrix Metaframe is a "thin client" software package that runs on top of
>Windows NT Terminal Server. It is essentially a 'throwback' to the old days
>of dumb terminals and mainframe computing.
>>
>>All processing and I/O is done on the Windows NT Server - which clients
>can connect to using the Citrix client software... the client sends
>keystrokes & mouse clicks to the server, and receives screen updates
>(similar to PC Anywhere). For more information:
>>
>>www.citrix.com
>>
>>Granted my experience with MetaFrame is limited to land-lines and dial-up
>connections - but I don't see how the software would adversely effect your
>satellite bandwidth.... and on a 128kbps connection (assuming low latency),
>you should be able to support 3-5 concurrent users.
>>
>>Regards,
>>Graham
>>
>>
>>
>>
>>Graham A. Fennie
>>Systems Engineer
>>Western NY Computing Systems, Inc.
>>(716) 381-4120 x7334
>>[email protected]
>>
>>>>> Dan Shell <[email protected]> 11/09/1999 2:58:41 PM >>>
>>Just what is a metaframe?
>>
>>And using TDMA should not cause a performance problem.
>>As Mark can tell you that the link utlilization in TCP/IP depends on the
>>quality of TCP/IP protocol stack and
>>if it has enable large windows (very important) adjustable buffers etc.)
>>
>>
>>At 01:53 PM 11/9/99 -0500, Mark Allman wrote:
>>>
>>>The following was sent to an old version of the tcpsat mailing list
>>>that doesn't exist.
>>>
>>>allman
>>>
>>>
>>>------- Forwarded Message
>>>
>>>From: [email protected]
>>>To: [email protected], [email protected], [email protected],
>>> [email protected]
>>>Date: Fri, 5 Nov 1999 19:10:14 -0400
>>>Subject: Help in Satellite comunications
>>>
>>>
>>> At the moment we are working in a project that requires the use of
>>>satellite
>>>communication.
>>>Looking for information in the Internet I arrived to your web page. We need
>>>to clarify some topics and maybe you can help us or give us references
>>>where to find answers.
>>>The scene it is more or less this:
>>>
>>>Four locations of work exist, each one of them consists of a network
>>>Ethernet with platform NT,
>>>gateway, the connection between this locations are by means of satellite
>>>communication using
>>>TDMA with Dynamic Location of Time, a bandwidth of 512 Kbps and using
>>>Metaframe of citrix with
>>>the TCP/IP protocol.
>>>
>>>The main problem to face is the possibility that this bandwidth is not well
>>>used: some of the technicians of the project argue that with metaframe the
>>>transmission is limited to 128 kbps and the 512 Kbps available will not be
>>>used, due to the TDMA with Dynamic Location of Time. For this reason my
>>>concern is to find a similar systems in operation that uses this
>>>technology.
>>>
>>>The system looks like this:
>>>
>>>Two Ethernet networks with platform NT, communicated by means of satellite
>>>using technology
>>>TDMA (Dynamic Location of Time) with a bandwidth of 512kb. On one side we
>>>have applications servers and in the other side we have around about 20
>>>concurrent clients of relatively heavy applications using protocol TCP/IP.
>>>
>>>My questions are:
>>>
>>>1) It is true that with this technology (TDMA with DLT) the maximum
>>>bandwidth that I will be able to use
>>>is 128 Kbps even if I have a channel of 512 kbps ?
>>>
>>>2) If the previous is true, how would be the way to increase the
>>>bandwidth
>>>an at what cost of the communication channel? What would be maximum real
>>>bandwidth of this 512 Kbps channel ?
>>>
>>>3) Could someone give me references of similar projects that have been made
>>>? Any reference on the use of the metaframe with satellite communication
>>>(TDMA with DLT) ?
>>>
>>>I will appreciate any help ...
>>>
>>>Thanks in advance.
>>>
>>>
>>>
>>>
>>>------- End of Forwarded Message
>>>
>>>
>>
>>Dan Shell
>>CISCO Systems Engineer Federal
>>Advanced Technologies
>>Wireless and Satellite
>>216 643 2422
>>
>>
>>
>
>
>
> "The quality of a network is not based on complexity but
> on it's simplicity and adherence to solid fundamentals."
>
>
>=====================================================================
>| Greg Otto e-mail: [email protected] |
>| Network Engineer voice: (713) 995-4778x102 |
>| New Frontier Consulting, Inc. fax: (281) 754-9170 |
>| Houston, Texas www: http://www.newf.com |
>=====================================================================
>
"The quality of a network is not based on complexity but
on it's simplicity and adherence to solid fundamentals."
=====================================================================
| Greg Otto e-mail: [email protected] |
| Network Engineer voice: (713) 995-4778x102 |
| New Frontier Consulting, Inc. fax: (281) 754-9170 |
| Houston, Texas www: http://www.newf.com |
=====================================================================
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