COMP 361 -- Week 14
Chapters 4 & 5
Problem 1: Is it necessary that every autonomous system use the same intra-AS routing algorithm? Why or why not?
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Problem 2: Suppose there are three routers between a source host and a destination host. Ignoring fragmentation, an IP address sent from the source host to the destination host will travel over how many interfaces? How many forwarding tables will be indexed to move the datagram from the source to the destination?
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Problem 3: Why are buffers needed at the output ports of a switch (router)? Why are buffers needed at the input ports of a switch (router)?
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Problem 4: By convention internet address 127.0.0.1 denotes the loopback address of the host's interface. However, suppose that the computer science department at HKUST chooses to place the following type A resource record entry in its domain name server:
<localhost.cs.ust.hk,127.0.0.1, A, IN>
Explain what will happen if a remote site tries to ping a machine with domain name localhost.cs.ust.hk?
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Problem 5: Suppose the information content of a packet is the bit pattern 1010101010101011 and an even parity scheme is being used. What would the value of the checksum field be for the case of a two-dimensional parity scheme? Your answer should be such that a minimum length checksum field is used. Also the checksum bits should be written after the data bits.
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Problem 6:
Show that two-dimensional parity checks can correct and detect a single bit error. Show (give an example of) a double bit error that can be detected but not corrected.¡@
Problem 7:
Suppose G=10011 and D is the value 1101011011. What is the value of R calculated by the CRC procedure. What is the value that will be transmitted?¡@
Problem 8:
In class we provided an outline of the derivation of the efficient of slotted ALOHA. In this problem we'll complete the derivation.
(B) Using the value of p found in Part a, find the efficiency of slotted ALOHA by letting N approach infinity (Hint:(1-1/N)N approaches 1/e as N approaches infinity.)
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