home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Internet Tools (InfoMagic)
/
Internet Tools.iso
/
dos_win
/
winsock
/
maillist
/
94-05.Z
/
94-05
/
000358_rcq@mailserv-D.ftp.com_Wed May 25 08:46:48 1994.msg
< prev
next >
Wrap
Internet Message Format
|
1994-05-31
|
3KB
Received: from ftp.com (wd40.ftp.com) by SunSITE.Unc.EDU (5.65c+IDA/FvK-1.07) with SMTP
id AA29026; Wed, 25 May 1994 12:48:20 -0400
Received: from ftp.com by ftp.com ; Wed, 25 May 1994 12:48:18 -0400
Received: from mailserv-D.ftp.com by ftp.com ; Wed, 25 May 1994 12:48:18 -0400
Received: from rcq.sidearm.ftp.com by mailserv-D.ftp.com (5.0/SMI-SVR4)
id AA17626; Wed, 25 May 94 12:46:48 EDT
Date: Wed, 25 May 94 12:46:48 EDT
Message-Id: <9405251646.AA17626@mailserv-D.ftp.com>
To: bagwell@netcom.com
Subject: Re: Winsock Paramters, please explain
From: rcq@ftp.com (Bob Quinn)
Reply-To: rcq@ftp.com
Cc: Multiple recipients of list <winsock@sunsite.unc.edu>
Sender: rcq@mailserv-D.ftp.com
Repository: mailserv-D.ftp.com, [message accepted at Wed May 25 12:46:43 1994]
Originating-Client: sidearm.ftp.com
Content-Length: 2247
> what do the following winsock parameters mean?
>
> MTU
Maximum Transmittable Unit. The size of this depends on the
media you are using (for example, the MTU for DIX Ethernet is
1514 bytes). There's no maximum, and the minimum specified in
the Path MTU-Discovery RFC 1191 is 68. RFC 1191 says 576 has
been the standard MTU (when going across a router), because IP
RFC 791 prescribes 576 for ARPANET to avoid fragmentation (so
it's a historical artifact).
> TCP RWIN
Transmission Control Protocol Remote Window. Look at the TCP
RFC (request for comments) 793 for details; essentially the
TCP Window gives the maximum number of bytes you can send to
a remote host (before the other side updates its window in a
TCP header it sends to you). Minimum is 0, and maximum is
65535 (window field in the TCP header is 16 bits, so that's
the maximum integer value it can hold). Generally this number
is not relevant to an application since TCP is a datastream.
> TCP MSS
Maximum Segment Size. Could be called the MTU for TCP; it is
the maximum amount of data per TCP packet. Since TCP is a
datastream that doesn't preserve packet boundaries, the MSS
is not something applications need to be concerned with (it
is handled by the lower layers). The MSS is negotiated when
a TCP connection is created. Minimum would be 1, and the max
is the MTU for the media in use, minus the media-specific, IP
and TCP header lengths. For example:
DIX Ethernet MTU is 1514
- 14 (DIX Ethernet Header Length)
- 20 (IP Header)
- 20 (TCP Header)
------------------
1460 bytes
Look at TCP RFC 793 for more info on MSS.
> what are the minimum and maximum values for each.
>
> Is this information defined in some FAQ or file of some kind.
Not that I know of. I think these are pretty common to many
TCP/IP and networking related glossaries, though. And you
should be able to find explanations in almost any book on
TCP/IP (e.g. those by Comer or Stevens).
Regards,
--
Bob Quinn rcq@ftp.com
FTP Software, Inc. No. Andover, MA