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Re: [Discuss-gnuradio] more gmsk issues

From: Greg Troxel
Subject: Re: [Discuss-gnuradio] more gmsk issues
Date: Mon, 22 Jan 2007 15:31:52 -0500
User-agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (berkeley-unix)

You are experiencing IP fragmentation.  This could explain why ping
still works.

Starting at id 32559, I can see both fragments in the .1 trace, but
only the first in the .2 trace.  Look at 
in the second trace, and note that offset 0 is present but not offset
480.  In the first trace at 
both fragments are there.

Is your transport protocol congestion friendly, meaning will it back
off when it doesn't get acks?  It seems to go down to 1 packet/second.

Could you set the MTU to avoid fragmentation, perhaps to 576 (ip
bytes)?  Or try scping a file, which will/should adapt MSS to MTU

The last 2nd fragment (meaning offset 480) is id 32558, so it seems
that your system in getting in a state where the second fragment is
always dropped.  Is there some queue which is always full or nearly
full and therefore when 2 back-to-back frames get sent the second is
always dropped?  Using TCP may avoid this problem, since it will back
off more aggressively.

It may be that you are finding bugs in your system's fragment
reassembly code.

    Greg Troxel <address@hidden>

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