Announcement

1
Announcement
2
Midterm

• Chapter 2 and 3
• (see Reading List for details)
• Lab 1, 2, and 3

3
Midterm

• 1 A4-size Cheat Sheet
• Some MCQ/Short Questions

4
Problem Set 4

• Clarification on Q3 Posted

5
Application
Transport
you are here
Network
Link
Physical
6
Transport (process-to-process)
Network (host-to-host)
Link (node-to-node)
7
(No Transcript)
8
Transport (process-to-process)
Network (host-to-host)
IP
ICMP
Routing Protocols
Link (node-to-node)
9
Routing
10
Internet is a network of networks

• A hierarchy of ISPs (Tier 1, 2, 3), each owns
  routers and links

11
Internet is a network of Autonomous Systems

• A hierarchy of ISPs (Tier 1, 2, 3), each owns
  routers and links

12
(No Transcript)
13
Inter-AS routing
Intra-AS routing
14
Addr Interface
X Y Z
1 1 3
15
4,294,967,296
16
Prefix Interface
11001 110 011
1 2 3
17
Abstract View of Routing
18
(No Transcript)
19
(No Transcript)
20
1
2
4
2
1
3
7
2
2
21
Shortest Path Problem in Graph
22
Link-State Routing

• Centralized,
• using Dijkstra algorithm

23
broadcast costs of links to each other
24
compute shortest paths locally (using global map)
25
Distance Vector Routing

• Distributed
• Asynchronous
• Iterative
• Self-Terminating

26
exchange local views with neighbors
27
update local views (based on neighbors view)
28
y
x
29
y
x
30
Bellman-FordEquation
31
v
y
x
32
7
v
9
y
5
2
8
x
4
33
7
9
y
5
v
2
8
x
4
34
Dest Next
y
v
35
Distance Vector
36
1
2
y
7
x
z
37
1
2
y
7
x
z
38
5
1
y
2
w
2
7
x
z
39
1
4
y
50
x
z
40
1
4
y
50
x
z
41
Count-To-Infinity Problem
42
PoisonedReverse
43
LS
DV
44
1
4
y
50
x
z
45
RIP

• Routing Information Protocol

46
Routing Table
47
Exchange every 30 seconds(over UDP)
48
if no ad from n for 180s assume n has failed
RIP Self-Repair
49
static routingload insensitive
50
Inter-AS routing
Intra-AS routing
51
(No Transcript)
52
BGP

• Border Gateway Protocol