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1

Protocols

ITEC 370

George Vaughan

Franklin University

2

Sources for Slides


Material in these slides comes primarily
from course text, Guide to Networking
Essentials,Tomsho, Tittel, Johnson (2007).


Other sources are cited in line and listed in
reference section.

3

TCP/IP and OSI Models

4

Function of Protocols


Protocol = Rules for communication


Protocols exist for each layer of OSI
model.


Some protocols span more than one layer.


Higher layer protocols are more abstract.


When protocols work together to cover
multiple OSI layers, they are referred to
collectively as a protocol stack (or suite).

5

Connectionless and Connection
-
Oriented Protocols


Connectionless


No guarantee of delivery


Low overhead, faster


Connections don’t have to be setup or torn down


Rely on upper layers to provide reliable communications


Connection Oriented


Reliable but slower


Receiver sends acknowledgement to indicate successful transfer


Packets are resent in event of error


Upper layers don’t have to worry about reliable transmission

6

Routable and Non
-
routable
Protocols


Routable


Operate at Network layer


Support internetworks (MAN, WAN)


Example: TCP/IP


Non
-
Routable


Does not operate at Network layer


Useful for small LANs


Example: NetBIOS Extended User Interface
(NetBEUI)

7

TCP/IP and OSI Models

8

TCP/IP
Network

Layer Protocols


Internet Protocol version 4 (IPv4 or IP)


Source and Destination logical addressing, routing


Connectionless


Fast but not reliable


Internet Control Message Protocol (ICMP)


Used to send error and control messages


Used by ‘Ping’ utility


Address Resolution Protocol (ARP)


Used to resolve logical (IP) address to physical
(MAC) address


Can only be used for two systems in same network.

9

Example of TCP/IP
Network

Layer
Protocols


Computer A needs to send a message to
Computer B


Before computer A can send message, it
needs the following addresses for computer B:


IP (logical address)


MAC (physical address)

1.
Computer A sends out ARP broadcast message to
all devices.

2.
Computer B recognizes IP address in ARP and
sends back MAC address to computer A

3.
Computer A now has 2 addresses necessary for
send message to computer B.

10

TCP/IP
Transport

Layer Protocols


Transmission Control Protocol (TCP)


Accepts messages of any length from upper layers


Connection
-
Oriented


Uses 3
-
way handshake to establish connection

1.
A sends ‘Synchronize’ (SYN) message to B

2.
B sends ‘Synchronize Acknowledgement’ (SYN
-
ACK) message
back to A

3.
A sends a ‘Forward Acknowledgment’ (ACK) to B

4.
Connection between A and B is now established.


TCP is responsible for fragmenting application into segments


TCP is responsible for reassembling the application data from
segments.


TCP uses Acknowledgment messages to:


Ensure that data is properly received.


Manage flow control

11

TCP/IP
Transport

Layer Protocols
(Cont.)


User Datagram Protocol (UDP)


Connectionless


Faster, but less reliable than TCP


UDP itself does not segment application data


UDP does not use acknowledgements


UDP is used by some higher layer protocols
such as NFS and DNS.


12

TCP/IP
Application

Layer Protocols


Domain Name System (DNS)


Name
-
to
-
Address resolution system


einstein.franklin.edu


65.24.7.3 (try
‘nslookup einstein.franklin.edu’


Hypertext Transport Protocol


Web
-
pages, browsers, servers


File Transfer Protocol (FTP)


Telnet


Simple Mail Transport Protocol (SMTP)

13

TCP/IP
Application

Layer Protocols


Tomsho, Tittel, Johnson (2007)



DHCP


Detailed configuration of devices, keeping track of assigned addresses
and to which machine they were assigned, etc., is difficult in large
networks


DHCP
was developed to make this process easier


DHCP server must be configured with a block of available IP
addresses and their subnet masks


Clients must be configured to use DHCP


Broadcast request message is sent on boot


Client leases the address the server assigns to it


If no answer is received, in an
APIPA
-
enabled OS, the
computer assigns itself an address (169.254.x.x)

14

IP Addressing


IP addressing is responsible for routing in
TCP/IP environment.


Example: 192.203.187.0


IP address is 32 bits long (4 bytes)


Special IP addresses:


255.255.255.255

= Broadcast


127.xxx.xxx.xxx

= Localhost


IP address is divided into 2 parts


Network Identification


Host Identification

15

Scope of Transmission


Hosts in same network (same Network ID)
can be connected with switches/hubs


Router is required to transmit to hosts
outside of network (different Network ID).


Broadcast messages can only be
transmitted to hosts within same network
(broadcast domain).

16

Types of IP Addressing


The demarcation point in the 32 bit
address between network ID and host ID
depends on addressing scheme:


Class Based Addressing generally uses a
byte boundary as the dividing point


Classless Based Addressing uses a bit
boundary.

17

Class Based IP Addressing

(Cisco


IP Addressing, n.d.).

Used less frequently now, CIDR preferred

18

Internet Protocol Version 6


Limitations with IPv4


32 bit address space is limited


No Quality of Service (QoS) support


IPv6 Features:


Incorporates IPSec


128 bit address


Auto
-
configuration


No IP address to assign


No subnet mask to determine


2 methods of auto
-
configuration


Stateless


Host creates its own IP address based on router information
and MAC address


Simplest and most common


Stateful


Relies on DHCP server

19

IPv6 Address Scheme


Hexidecimal grouped in 16 bit sections:


2001:1b20:302:442a:110:2fea:ac4:2b


Leading zeroes are eliminated


2 or more 16 bit fields of all zeros can be ignored:


2001:260:0:0:0:2ed3:340:ab (long form)


2001:260::2ed3:340:ab (short form)


IPv6 has 3 parts:


20

Other Protocol Suites


Tomsho, Tittel, Johnson (2007)



Other protocol suites are sometimes used
on older networks, where the need to
change to TCP/IP is not warranted, or in
environments suited to the suite’s features


NetBIOS/NetBEUI


Used primarily on older Windows networks


IPX/SPX


Designed for use on NetWare networks


AppleTalk


Used almost exclusively on Macintosh networks

21

References


Tomsho, Tittel, Johnson (2007).
Guide to Networking
Essentials.

Boston: Thompson Course Technology.

Odom, Knott (2006).
Networking Basics: CCNA 1
Companion Guide
. Indianapolis: Cisco Press

Wikipedia (n.d.).
OSI Model
. Retrieved 09/12/2006 from
http://en.wikipedia.org/wiki/OSI_Model

Cisco


IP Addressing (n.d.). IP Addressing. Retrieved
09/27/2006 from
http://cco.cisco.com/warp/public/701/3.html#figone

IANA (n.d.)
Abuse Issues and IP Addresses .
Retrieved
11/11/06 from
http://www.iana.org/faqs/abuse
-
faq.htm