Chapter 1: Overview
1.1 Layers
1.3 Packets
1.4 Datagram Forwarding
1.5 Topology
1.6 Routing loops
1.7 Congestion
1.8 Packets again
1.9 LANs and Ethernet
1.10 IP
1.12 Transport
Chapter 2:
2.1 10-Mbps classic Ethernet
2.2 100-Mbps Ethernet
2.4 Ethernet Switches
Chapter 3: Other LANs
3.6, 3.7: Wi-Fi
(virtual circuits are officially dropped)
Chapter 4: Links
4.1 Encoding and Framing
Chapter 5: Packets
5.1: delay
5.2: delay variability
5.3: packet size
Chapter 6: Sliding Windows
6.1: stop-and-wait
6.2: sliding windows
6.3: bottlenecks
Chapter 7:
7.1 The IPv4 header (you do not
need to memorize the specific layout)
7.5 Classless IP delivery
7.6 Subnets
7.8 ARP
Chapter 9:
9.1: distance-vector
9.2: slow-convergence problem and fixes
9.3: slow-convergence fixes
Chapter 11: UDP
11.1: UDP
11.2: fundamental transport issues
12.3: connection establishment
12.6: state diagram
12.7: old duplicates
12.8: TIMEWAIT
12.9: 3WHS
12.10: anomalous scenarios
A B C │ │ │ S1────────S2────────S3 │ │ S4───D
A───S1 │ D │ │ C───S3────────S4─────────S5 │ │ │ E B───S2
S1─────S4─────S10──A──E │ │ │ │ S2─────S5─────S11──B │ │ │ │ S3─────S6─────S12──C──D──F
S1────────S2────────S3───D │ │ │ A B C
B │ S4 │ A───S1────────S2────────S3───C │ DNow suppose the following packet transmissions take place:
For each switch, list what source addresses (eg A,B,C,D) it has seen (and thus what nodes it has learned the location of).
8 (omitted).
Chapter 5: packets and delay
2.
Suppose the path from A to B has a single switch S in between:
A───S───B. Each link has a propagation delay of 60 µsec and a bandwidth
of 2 bytes/µsec.
(a). How long would it take to send a single 600-byte
packet from A to B?
(b). How long would it take to send two back-to-back
300-byte packets from A to B?
(c). How long would it take to send three
back-to-back 200-byte packets from A to B?
6. Suppose we have five links, A───R1───R2───R3───R4───B. Each link has
a bandwidth of 100 bytes/ms. Assume we model the per-link propagation
delay as 0.
(a). How long would it take a single 1500-byte packet
to go from A to B?
(b). How long would it take five consecutive 300-byte
packets to go from A to B?
Chapter 6: Sliding windows
3. Create a table as in the text's Section
6.3.1: Simple fixed-window-size analysis for the original
A───R1───R2───R3───R4───B network, with 1 packet/sec bandwidth delay for
the R1⟶R2, R2⟶R3, R3⟶R4 and R4⟶B links. The A–R link and all reverse links
(from B to A) are infinitely fast. Assume winsize = 8. Carry out the table
for 10 seconds.
5. Suppose RTTnoLoad = 4 seconds and the bottleneck bandwidth
is 1 packet / 2 seconds.
(a). What window size is needed to remain just at the
knee of congestion?
(b). Suppose winsize=6. How many packets are in the
queue, at the steady state, and what is RTTactual?
8. Suppose RTTnoLoad is 50 ms and the available bandwidth is
2,000 packets/sec. sliding windows is used for transmission.
(a). What window size is needed to remain just at the
knee of congestion?
(b). If RTTactual rises to 60 ms (due to use
of a larger winsize), how many packets are in a queue at any one time?
(c). What value of winsize would lead to RTTactual
= 60 ms?
(d). What value of winsize would make RTTactual
rise to 100 ms?
Chapter 7: IPv4
4. The following diagram has routers A, B, C, D and E; E is the “border
router” connecting the site to the Internet. All links are via /24 subnets
of the form 200.0.x. Give forwarding tables for each of A, B, C and D.
Each table should include each of the listed subnets and also a default
entry that routes traffic toward router E.
200.0.5────A────200.0.6────B────200.0.7────D────200.0.8────E────Internet │ 200.0.9 │ C │ 200.0.10
3. Suppose a router R has the following distance-vector table:
destination | cost | next hop |
---|---|---|
A | 5 | R1 |
B | 6 | R1 |
C | 7 | R2 |
D | 8 | R2 |
E | 9 | R3 |
R now receives the following report from R1; the cost of the R–R1 link is 1.
destination | cost |
---|---|
A | 4 |
B | 7 |
C | 7 |
D | 6 |
E | 8 |
F | 8 |
8. Suppose the routers are A, B, C, D, E and F, and all link costs are 1. The distance-vector forwarding tables for A and F are below. Give the network with the fewest links that is consistent with these tables. Hint: any destination reached at cost 1 is directly connected; if X reaches Y via Z at cost 2, then Z and Y must be directly connected.
A’s table
destination | cost | next hop |
---|---|---|
B | 1 | B |
C | 1 | C |
D | 2 | C |
E | 2 | C |
F | 3 | B |
F’s table
destination | cost | next hop |
---|---|---|
A | 3 | E |
B | 2 | D |
C | 2 | D |
D | 1 | D |
E | 1 | E |
6. Suppose that, after downloading a file, a user workstation is unplugged from the network. The workstation may or may not have first sent a FIN to start closing the connection.
A sends | B sends |
---|---|
SYN, ISNA=20000 | |
SYN, ISNB=5000, ACK=______ | |
ACK, SEQ=______, ACK=______ | |
Data1, SEQ=______, ACK=______ | |
ACK, SEQ=______, ACK=______ | |
Data2, SEQ=______, ACK=______ | |
ACK, SEQ=______, ACK=______ | |
Data3, SEQ=______, ACK=______ | |
ACK, SEQ=______, ACK=______ | |
DataB, SEQ=______, ACK=______ | |
ACK, SEQ=_____, ACK=______ | |
FIN, SEQ=______, ACK=______ |