Frames, Buffers,and Messages
As this
section has suggested, the network adaptor is the place where the network comes
in physical contact with the host. It also happens to be the place where three
different worlds intersect: the network, the host architecture, and the host operating
system. It turns out that each of these has a different terminology for talking
about the same thing. It is important to recognize when this is happening.
From the network’s
perspective, the adaptor transmits frames
from the host and receives frames
into the host. Most of this chapter has been presented from the network perspective,
so you should have a good understanding of what the term “frame” means. From
the perspective of the host architecture, each frame is received into or
transmitted from a buffer, which is
simply a region of main memory of some length and starting at some address.
Finally, from the operating system’s perspective, a message
is an abstract object that holds network frames. Messages are
implemented by a data structure that includes pointers to different memory
locations (buffers).
happy reading^^...
