Homework
2 Answers
Jeffrey
Absher
xxx-xx-xxxx
31.
(5 pts) Ex. 47 in Chapter 13.
How does the Hop Count limit alleviate RIP’s Problems?
It doesn’t totally, but it does lower the maximum and average convergence
time
32.
(10
pts) Ex. 48 in Chapter 13.
List RIP shortcomings and their corresponding fixes
Counting to inifinity – split horizons/Best Info/poison reverse
Long Wait after change – Triggered update
Slow convergence – Maximum hop count, triggered update
Only uses Hop Counts (no fix)
33.
(20
pts) Ex. 52 and 54 in Chapter 13.
52 compare and contrast Distance-Vector w/ Link-State
Both are dynamic
DV shares info about the entire Autonomous System while LS shares info about
its neighborhood’s link states
DV only shares info with nodes’ neighbors while LS floods to every other router
DV (generally) has timed interval updates LS updates upon a change or change
threshold.
54 Why do OSPF messages propagate faster than RIP messages?
Link State shares info when a change occurs with all other routers
immediately. With Distance Vector, if a router is 5 hops away, it takes 5x(15)
seconds on average to share info. More generally if n is the minimum number of
hops between routers and i is the maximum refresh interval O(n*i), o(n) q(n*i/2).
34.
(10
pts) Ex. 59 in Chapter 13.
What would be the contents of the table?
Net1 2 C
Net2 1 C
Net3 1 F
Net4 5 G
35.
(10
pts) Ex. 75 in Chapter 13.
Draw the graphical representation of the autonomous system from ex 74 as seen
by OSPF
See attached sheet
36.
(20
pts) Apply Dijktra’s algorithm to Figure 13.23 (p. 337) in the text to find the
shortest paths from node C to all the other nodes. You must show your work
using the Dijkstra’s algorithm. To break a tie, choose the node that is lower
according to the alphabetical order.
|
perm |
discovered |
|
C |
N2(2,C)
N1(3,C) |
|
C
N2(2,C) |
N1(3,C) |
|
C
N2(2,C) N1(3,C) |
A(3,N1)
B(3,N1) |
|
C
N2(2,C) N1(3,C) A(3,N1) |
B(3,N1)
D(11,A) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) |
D(11,A)
E(7,B) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) |
D(11,A)
N4(9,E) N3(12,E) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) N4(9,E) |
D(11,A)
N3(12,E) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) N4(9,E) D(11,A) |
N3(12,E)
N3(13,D) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) N4(9,E) D(11,A) N3(12,E) |
N3(13,D)
F(12,N3) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) N4(9,E) D(11,A) N3(12,E) F(12,N3) |
N3(13,D)
N5(17,F) |
|
C
N2(2,C) N1(3,C) A(3,N1) B(3,N1) E(7,B) N4(9,E) D(11,A) N3(12,E) F(12,N3)
N5(17,F) |
N3(13,D) |
|
Algorithm
terminates |
|
37.
(5
pts) Ex. 26 in Chapter 16.
Determine which of the following is a FQDN and which is a PQDN:
a.
mil.
FQDN
b.
edu.
FQDN
c.
xxx.yy.net
PQDN
d.
zzz.yyy.xxx.edu
PQDN
38.
(5
pts) Ex. 17 in Chapter 19.
Why do we need a RRQ or WRQ message in TFTP, but not in FTP?
We need these requests because TFTP uses UDP and simulates connections to
perform both data transfer and control communication while FTP has a TCP
connection dedicated to data transfer and a TCP connection dedicated to control
39.
Not Assigned
40.
(20
pts) Ex. 47 in Chapter 20.
Encode the following messge into base64
01010111 00001111 11110000
10101111 01110001 01010100
010101 110000 111111 110000 101011 110111 000101 010100
21 48 63 48 43 55 5 20
Vw/wr3FU