Chapter 5 TCP/IP: Routing Part 2

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Oct 29, 2013 (3 years and 10 months ago)

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Chapter 5


TCP/IP: Routing


Part 2

Dr. V.T. Raja

Oregon State University

TCP/IP


Routing
-

Part 2

Outline

Routing Protocols

Unicast messages

Broadcast messages

Routing Tables

Routing Protocols

Autonomous System of Networks

Each large organizational network connected to Internet
(e.g., AT&T, IBM, OSU) can be viewed as a separate
autonomous system

Computers within each autonomous system usually
exchange routing information among themselves

Routing protocols used inside an autonomous system
are called
interior routing protocols

Routing protocols used between autonomous systems
are called
exterior routing protocols

Routing Protocols

Internet Control Message Protocol

(ICMP)


Error advisement


Example: Ping command


Host (Destination)
unreachable



Flow control


Requesting a device to reduce the rate at which it
transmits

Routing Protocols

Routing Information Protocol

(RIP)


Dynamic distance vector routing protocol


Scalability: 15
-
hop limit


Good for smaller networks


Broadcast interruptions (entire routing table
transmitted very often)


Slower convergence


Takes a longer time for
routing tables to be transmitted very often

Routing Protocols

Open Shortest Path First

(OSPF)


Link State Dynamic Routing Protocol


Faster convergence


Designated router updated on changes in route status

Border Gateway Protocol

(BGP)


Distance Vector Dynamic Routing Protocol


Used between autonomous systems


Changes in route status info transmitted

Comparison of Routing Protocols

RIP

OSPF

BGP

Interior/Exterior?

Interior

Interior

Exterior

Type (Distance Vector/

Link State?)

Distance Vector

Link State

Distance Vector

Routing update content

(Routing Table/Updates?)

Routing Table

Updates only

Updates only

Routing update frequency

Very often (e.g.,
every 30
seconds)

Updates only

Updates only

Convergence

(Slow/Fast/Complex?)

Slow

Fast

Complex

Scalability

Poor

Very Good

Very Good

TCP/IP and Routing

TCP/IP can use RIP, ICMP,
OSPF, BGP

It is compatible with distance
vector and link state
protocols

Can operate either as
connectionless or connection
oriented routing

Can support QoS routing (a
new version of OSPF called
QOSPF)

Unicast/Broadcast

Unicast


Most common type of
message transmitted
(from one sender to one
final destination)


Example:

Broadcast


Subnet broadcast


Example



LAN broadcast


Example

Routing Tables

Routing Table for B

Destination


Route



A


A



C


C



D


A



E


E



F


E

G


C


Default


A

Routing Table

(Continued)

Network

Destination

Netmask

Gateway

Interface

Metric

(Cost)

Default route
: 0.0.0.0

0.0.0.0

128.193.76.1

128.193.77.65

20

Loop back

(Self)

127.0.0.0


255.0.0.0


127.0.0.1


127.0.0.1


1

Network Route

128.193.76.0


255.255.254.0


128.193.77.65


128.193.77.65


20

Local Host

128.193.77.65


255.255.255.255


127.0.0.1


127.0.0.1


20

Subnet broadcast

128.193.255.255


255.255.255.255


128.193.77.65


128.193.77.65


20

Multicast
: 224.0.0.0

240.0.0.0

128.193.77.65

128.193.77.65

20

Broadcast

255.255.255.255


255.255.255.255


128.193.77.65


128.193.77.65


1

Introduction

Router Forwarding Table

Destination Address

Prefix (Mask)

Metric (Cost)

Interface

Next
-
Hop Router

172.19.

16 (255.255.0.0)

47

2

G

172.19.17

24

55

3

H

172.229.

16

34

1

F

172.229.

16

20

3

H

172.15.122

24

3

3

Local

0.0.0.0

0

5

3

H