[nos-bbs] Interested in REPEAT packet statistics?

Kenneth C Coe Jr kd8ipn at coehome.com
Wed Apr 14 04:44:39 EDT 2010

Sorry, Skip, I didn't realize you were waiting for an answer. I was
still waiting for the rest of the question. Actually, I still am.

As usual for your posts, half the information that is needed. You simply
cannot boil a complex problem down to one or two sentences and expect an
answer worth its weight in salt.

The reason I snapped at you (trite or not), is simple. I have been
watching emails come from you for a while, pointing out what you say are
problems with the way the network is designed. You keep posting these
snippets of "data" and saying you are requesting an answer to your
question, making a  habit of ignoring other peoples requests for the
right information and just recycling the same old mess of numbers for
your next question (or proposal, or whatever it is).

I have seen a lot of good information proposed to you in past emails,
and you appeared to have ignored it or not even heard. You certainly
didn't hear mine, because you replied to my answer about only posting a
small piece of the information with another snippet. Did you really
expect an answer, or are you just trying to get yelled at?

As far as the dumps, just post them somewhere and tell us where they
are. We can download them...


On Tue, 2010-04-13 at 22:38 -0400, George [ham] VerDuin wrote:
> HI Barry, you're not Kenneth who tells me nothing is wrong...:-)
> On 04/13/2010 03:09 PM, Barry wrote:
> >
> >> Now let's say after the third then you receive 3 duplicate
> >> ACKS.
> >>      
> > I love math problems!
> >    
> There is some math involved, it centers on the values of SRTT and MDEV.
> These buggers are built into jnos -- you can see them via the status 
> commands.
> >> What does the fact you receive dup ACK tell you about your
> >> own node?
> >>      
> > That your own node has a T1/Retry timer set to expire at least
> > three times faster than it should be?
> >    
> Not necessarily three times, but significantly non the less.
> Now if the packest are the SYN packets you are spot on.
> A large part of the issue is that you as sysop only have IRTT to adjust.
> Backoff strategy, begins to play,
> maxtime can be really bollixed up,
> blimit might be set too low,
> retrys might be a big number,
> but mostly these things play big time only after 3 or 4 repeats.
> But quite frankly damn the bullets.
> The detail is not what my example is about.
> Facts seem to bear out that re-transmission is
>       out of sight -- out of mind for many of us.
> Repeats are one of the most annoying aspects of opening a connection.
> And because slow initial response annoys us, we tend to shorten up on 
> the variables listed above in the belief we are better off when the 
> opposite is the truth.
> Back to math.
> Wait time in jnos2.0h is based on the formula:
>      Wait = srtt + 4 * mdev
> There are conditions when this formula servers us less well.
> If you are a student of classical statistics, you might enjoy looking.
> Also there is a timer-race between AX and TCP or AX and NET/ROM that 
> adds to un-necessary repeats.
> You have however captured the essence of my question:
> Seeing 3 ACKS means you sent 2 too many packets.
> For whatever reason.
> Perhaps under your control.
> Perhaps not.
> Two packest of three are not required, and no rebuttal is available.
> It's also likely the two extras slowed the first response making it worse.
> What to do about repeats is a long story.
> When to do it is my focus at this moment.
> Without looking, then "never" is the answer.
> The script I attached is one way of looking out of many ways.
> Thanks Barry
> Skip
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