Re: offloading the protocols


CERF@A.ISI.EDU
17 Mar 1988 05:12-EST


I'm not goin to get into the front-end versus operating system resident
protocol argument (I argued against the front-end years ago on the same
basis you suggest Dave Clark argues, if anyone cares about my historical
biases).

However, it seems to me that as you approach the gigabit channels, you
really want to simplify the host's view of networking. An analogy might be
found in disk/file access and virtual memory. Years ago, an operating
systme was designed at UCLA called the Sigma EXperimental system (SEX for
short - the user's manual was a popular item!). It ran on a Sigma 7 made
by Scientific Data System (later, Xerox Data Systems, later, R.I.P.).

The notion of associating ("coupling" - God, I never thought about how
suggestive that term was in connection with the operating system acronym)
virtual memory with pages of files was an essential design element.

One would associate a particular virtual page space with disk pages
occupied by a file. This is not much different than virtual memory
linked to pages of a disk, except in this case, actions to the memory
content were reflected in changes to the FILE (not just changes to a
disk page which happened to represent a page of virtual memory space).

So, the user's virtual memory space was mapped onto the file system. I
imagine Multics could be considered to have done something like that
only even more elegantly with its rich addressing structure.

Perhaps what is needed is a way to associate virtual memory with places
in the networking space. Writing to virtual memory would be like writing
to the network. PDP-11's had the concept of associating certain words of
memory with I/O channels. But what I am looking for is a notion that lets
very simple actions to memory be interpreted by outboard processors as
network-related actions.

Perhaps Dave Clark could expand on his theme which I view as related to
your question if not the rather poorly expressed ideas above.

Vint Cerf



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