[ARGUS] BSD argus/Linux ra problems?

[Michael Sanderson]

Carter Bullard wrote:

> Hey Michael,
>    Well that will cause a problem if a ra* client gets less than 128
> bytes, as we do a single read for 128 bytes and if we don't get it we
> exit.  There were a lot of reasons for this, but most were/are
> historical. I can modify it to get into a loop to read until we
> get 128 bytes, but it will not be pretty.
> 
>     I'm gonna be somewhat depressed by this, as it will introduce
> some delay in getting started when we've got multiple endpoints
> to manage.  Any way we can get BSD to change its IP stack? ;o)

I think that the delay will be pretty minor.  In most cases, you will 
still do a single read and you're off.  In the weirdo cases like mine, 
the delay between the first and second packets is about 5 milliseconds 
according to tcpdump.

> On the serious side, I wonder if I can force the starting window
> size on the client side to ensure that I have 128 bytes to start
> with?

The theory is that if you set the maximum send and receive buffer sizes 
before doing the connect that you can alter the window size. 
(http://www.ncsa.uiuc.edu/People/vwelch/net_perf/tcp_windows.html#bufsize 
has some sample code for clients and servers.)  I just tried this and it 
was not effective in my case - ie. same problems with a 46 byte window 
size - presumably since it only sets maximum buffer sizes not current 
the window size.  (Either that or the Linux kernel is just busted, which 
wouldn't surprise me all that.)

      Michael Sanderson