CMPT 371, HW 3  Due: March 14


1.  A and B have established a TCP connection.  A wants to send
a file of size 1 Mb = 2^{20} bits to B.  A's transmission rate is R bits/sec
and there is a fixed round-trip time of RTT seconds.  The MSS = 1 Kb =
2^{10} bits.  Assume there is never any segment loss and that B's
receive buffer is big enough to hold the entire file.

a.  How long does it take A to send the entire file if it begins
in slow-start mode (the initial window size is 1 MSS).

b.  How big is A's send window when it is finished sending the entire
file?

c.  How long would it take A to send the entire file if it were in 
AIMD mode starting with a window size of half the value from part (b)?




2.  Consider a connected network with N routers such that each
router has 4 interfaces.  Describe such a network that has as many
subnets as possible.  Describe one with as few subnets as possible.



3.  Consider a forwarding table at a router that uses 5-bit addresses.
If we want at most 7 different addresses to be forwarded on each link
interface, what is the minimum number of link interfaces there need to be?  
Write down such a table in range form (like on the bottom of page 311).
Write it down in prefix form (like on the top of page 312).



4.  Consider the following graph where N = {u,v,x,y,z} and
E = {(u,v,3),(u,x,2),(v,y,4),(x,z,1),(y,z,1)} (the number in each
edge denotes its cost).  

a.  Draw the graph.

b.  Show an execution of the Link-State algorithm on the graph as in table
4.3.  Let u be the source node.

c.  Consider a synchronous version of DV where, in the first round, every
node starts by sending its distance vector to its neighbors.  Then, all
nodes update their own distance vectors given the vectors they have received,
and, in the next round, each node whose vector has changed sends it 
out to its neighbors, etc.  List the messages that u will receive in
each round of DV until the algorithm terminates.