Name: 
RUID:

Assignment 3


1. Read Lamport's paper on Time, Clocks, and the Ordering of Events
in a Distributed System.
(a) What is Lamport's definition of concurrent events using the
happened before relation?


(b) What is Lamport's definition of concurrent events using the
concept of causality?


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2. Assign Lamport timestamps to each event. Assume that the clock
on each processor is initialized to 0 and incremented before each
event. For example, event a will be assigned a timestamp of 1.

	a: 1
	b: 
	c: 
	d: 
	e: 
	f: 
	g: 
	h: 

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3.
(a) Assign vector timestamps to each event in question 2. Assume
that the vector clock on each processor is initialized to (0,0,0,0)
with the elements corresponding to (P1, P2, P3, P4). For example,
event a will be assigned a timestamp of (1, 0, 0, 0).

	a: (1, 0, 0, 0)
	b: 
	c: 
	d: 
	e: 
	f: 
	g: 
	h: 

(b) Which events are concurrent with event d?


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4. You are synchronizing your clock from a time server using
Cristian's algorithm and observe the following times:
 timestamp at client when the message leaves the client: 10:44:20.400
 timestamp generated by the server: 9:20:10.200
 timestamp at client when the message is received at client: 10:44:21.200
(a) To what value do you set the client's clock?


(b) If the best-case round-trip message transit time is 124 msec
(0.124 sec), what is the error of the clock on the client?


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5. Explain the multicast support available in the Intel 8254x family
of Gigabit Ethernet Controllers (e.g., filtering by hashing an
address? ... exact addresses?).


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6. While IP multicast failed to gain widespread use for many "generic"
IP-based applications, it is a key component of IPTV (TV broadcast
over IP) deployments.
(a) According to the second article, how much network bandwidth is
needed for 100 channels?


(b) What is an advantage of using multicast for IPTV?


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