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Systems Depth Exam
Sept 2, 1998
You must answer all questions.
Do not write any answers on this paper. Only mark your name and code
on this paper. Write all your answers on the blank paper provided to
you. Only use one side of each sheet of paper. Write your code at
the top of each sheet of paper. Do not write your name on your answer
sheets.
- 1.
- Communication-kernel operating systems promote an organization where as
little as possible is in the kernel. Discuss what parts of memory management
can be taken out of the kernel, and give examples where appropriate of studies
that have tried that approach to memory management.
- 2.
- Design the protocol by which a client kernel will speak to a file-server
kernel. You may assume the client is running Unix, but you may not assume that
for the file server. Describe your protocol in terms of query types and
response types, with parameters. Your protocol should allow the client to
cache files if it wishes and should support multiple clients (and cache
consistency). You do not need to show how the various calls are implemented,
but you should give a clear idea of what they mean.
- 1.
- In general, user services provided by a store-and-forward
network can be characterized as being either ``connection-oriented''
or ``connection-less'':
- (a)
- Describe these two classes of services and point out the
advantages and disadvantages of each.
- (b)
- What are the tradeoffs between providing the two forms of
service with respect to the workload imposed on the user and the
workload imposed on the network?
- 2.
- Do ATM networks provide flow-control? If so, explain how.
If not, explain why a network technology that provides QoS doesn't
provide flow-control.
- 3.
- Active networks allow applications/protocols to inject code into
routers in the network. Some experts are now arguing that this
feature should be used sparingly, injecting only a small amount of
code in the ``inner'' network routers and instead injecting most of
the code in the routers at the periphery of the network.
In other words, the majority of the responsibility for standard
network functions such as reliability, flow control, congestion
avoidance/control would be implemented at the edge of the network.
The routers in the middle would only have enough code to help out with
these functions.
- (a)
- Argue for the experts.
- (b)
- Argue against the experts.
- (c)
- Would your recommend implementing reliable multicast this way
(with most of the reliabilty code residing at exterior routers)? Explain.
James Griffioen
9/11/1998