On Tuesday, May 28, 2002, at 02:45 AM, Seth Kurtzberg wrote:

> I guess it depends on what you consider to be part of CSMA/CD.  
> Exponential
> backoff definitely has functionality in the stack.

CSMA/CD, including exponential backoff, as part of Ethernet 
functionality is implemented in the hardware that interfaces to the 
cable.  There is no code in any system I've ever worked with to handle 
that.

There is code in the kernel's "netinet" directly to handle backoff in 
TCP connections, which may be what you are thinking of.  This is handled 
by code related to TCP timers.

This code has nothing to do with backoff in trying to send a single 
datagram/frame.  It is used to keep probing a "stuck" TCP connection and 
not flood the network and increase congestion problems.

Regards,

Justin

> On Tuesday 28 May 2002 01:17 am, Ignatios Souvatzis wrote:
>> On Tue, May 28, 2002 at 01:20:08AM -0700, Seth Kurtzberg wrote:
>>> It isn't really in a single place.  Part is clearly in the ethernet
>>> device driver code, and I believe the exponential backoff is further 
>>> up
>>> the stack.
>>
>> I believe you're mistaken. That code is implemented in hardware (well,
>> maybe in microcode for the hardware controller) for all Ethernet 
>> devices I
>> know about.
>>
>> Regards,
>> 	-is
>
> --
> Seth Kurtzberg
> MIS Corp.
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>
>
--
Justin C. Walker, Curmudgeon-At-Large  *
Institute for General Semantics        |   If you're not confused,
                                        |   You're not paying attention
*--------------------------------------*-------------------------------*