[nsp] Frame bursting

[warner at cats.UCSC.EDU]

> AFAICT, no vendor has ever built half-duplex GigE equipment.  All
> vendors provide full-duplex GigE only, and normal inter-frame gaps are
> used between frames on full-duplex links. 

Many switches have special modules used to gang heaps of switches
together.  Some of these proprietary modules are, in fact, half-duplex
Gig-E.  Here's a screen shot from the management interface of an
HP2524 switch.  Look at the mode of the stacking module on port 25.

                   Intrusion                               Flow   Bcast
  Port    Type       Alert    Enabled  Status     Mode     Ctrl   Limit
  ----  ---------  ---------  -------  ------  ----------  -----  ------
  16    10/100TX   No         Yes      Up      10HDx       off    0     
  17    10/100TX   No         Yes      Up      10HDx       off    0     
  18    10/100TX   No         Yes      Up      10HDx       off    0     
  19    10/100TX   No         Yes      Down    10HDx       off    0     
  20    10/100TX   No         Yes      Down    10HDx       off    0     
  21    10/100TX   No         Yes      Up      10HDx       off    0     
  22    10/100TX   No         Yes      Down    10HDx       off    0     
  23    10/100TX   No         Yes      Down    10HDx       off    0     
  24    10/100TX   No         Yes      Down    10HDx       off    0     
  25    1000Stk    No         Yes      Up      1000HDx     off    0     
  26               No         Yes      Down                off    0     

-jim