I ran into a very interesting half-duplex anomaly the other day:

My bandwidth is nominally 2mb/20mb, but is reliably about 1.1mb up and
11mb down
My shaping policy is based on the latter presumptions.  
Like most affordable 'net connections (cable, dsl) my speeds are HALF
duplex, unlike expensive T's, multilink T's and fiber Ethernet etc which
are all of course full duplex.  

Not surprisingly my UPLINK is pushed closer to its reliable maximum that
my fat downlink.  The phenomenon is that when my uplink is pegged (and
flowing perfectly without notable dropped packets), my maximum downlink
is effectively squeezed, and I lose RTP packets. I presume because there
are fewer open 'frames' remaining in which to stuff inbound packets
because I'm cramming them full of outbound packets.  

At present the only way I can think to avoid this problem is to throttle
back my uplink even FURTHER which causes me to lose even more precious
upstream bandwidth.  Is that the only way to deal with this issue?  

I would think there could be a dynamic shaping policy with a 'half
duplex' checkbox in the shaping wizard that changes shaping policy
dynamically based on the load seen on the opposite leg of the
connection, and the ratio of asymmetry on the pipe.  I imagine it would
be quite tricky to implement on the back end.  

I'm new to forum so I presume this may have been discussed before.  If
not, I welcome everyone to weigh in.  My understanding is that 1.3 (and
1.2.1?) has a new shaping engine.  Is this a design consideration?

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