[e2e] TCP out of order

[Douglas Otis]

Michael,

The store time for the larger packet puts it at a disadvantage in being
placed into a forward queue.  Packets may not be processed immediately so
should the completion of a larger packet just miss a process window, a
trailing smaller packet then has a chance of getting placed ahead as there
are places within packet buffering that may violate a packet sequence order.
A descriptor ring could be one such area.

Doug

> > Note that you can get very consistent packet reordering even if the
> > speed-of-light delay difference is zero and the circuit bandwidths
> > are identical, if the packets being generated are sometimes different
> > sizes.  That is, if you send a big packet followed by a small
> > packet, the small packet will always catch up to and pass the big
> > packet if they traverse enough store-and-forward hops.
>
> Forgive my ignorance - but: why?
>
> Michael