3. Objectives
Operation of IP Data Networks
• Recognize the purpose and functions of various network devices such as
Routers, Switches, Bridges and Hubs.
• Select the components required to meet a given network specification.
• Identify common applications and their impact on the network
• Describe the purpose and basic operation of the protocols in the OSI and
TCP/IP models.
• Predict the data flow between two hosts across a network.
• Identify the appropriate media, cables, ports, and connectors to connect
Cisco network devices to other network devices and hosts in a LAN
LAN Switching Technologies
• Determine the technology and media access control method for Ethernet
networks
Identify basic switching concepts and the operation of Cisco switches.
• Collision Domains
• Broadcast Domains
4. Internetworking Basics
Internetworking is the practice of connecting a computer network with
other networks through the use of gateways that provide a common
method of routing information packets between the networks. The
resulting system of interconnected networks is called an internetwork,
or simply an internet.
Collision is the result of two devices on the same segment trying to
transmit data at the same time
Collision domain is a term used to describe a network collection of
devices in which one particular device sends a packet on a network
segment, forcing every other device on that same segment to pay
attention to it.
Broadcast is message that can be accessed by any/every device on
the network
Broadcast Domain a set of all devices on a network segment hear all
broadcasts sent on that segment
7. Switches can replace the hub, breaking up
collision domains.
Keep in mind that the hub used in the figure just extended the one
collision domain from the switch port.
8. Here’s a list of some of the things that commonly cause LAN
traffic congestion:
•Too many hosts in one network/broadcast domain
•Broadcast storms and Multicasting
•Low bandwidth
•Adding hubs for connectivity to the network
•A bunch of ARP or IPX traffic (IPX is a Novell protocol that is
like IP, but really, really chatty. Typically not used in today’s
networks.)
11. There are two advantages of using routers in
your network:
•They don’t forward broadcasts by default.
•They can filter the network based on layer 3 (Network layer)
information (e.g., IP address).
Four router functions in your network can be
listed as follows:
•Packet switching
•Packet filtering
•Internetwork communication
•Path selection
12. The OSI Model
The OSI isn’t a physical model. Rather, it’s a set of guidelines that
application developers can use to create and implement
applications that run on a network.
It also provides a framework for creating and implementing
networking standards, devices, and internetworking schemes.
Reduces complexity
Standardizes interfaces
Facilitates modular engineering
Ensures interoperable technology
Accelerates evolution
Simplifies teaching and learning
22. TCP/IP and the DOD Model
The figure shows a comparison of the DoD model and the OSI
reference model. As you can see, the two are similar in concept,
but each has a different number of layers with different names.
23. The TCP/IP Protocol Suite
The DoD and OSI models are alike in design and concept and have
similar functions in similar layers.
24. Process/Application Layer
This section describes different applications and services typically
used in IP networks. The following protocols and applications are
discussed:
Telnet : is a protocol whose specialty is terminal emulation. It allows
a user on a remote client machine, called the Telnet client, to
access the resources of another machine, the Telnet server
FTP (File Transfer Protocol): is the protocol that actually lets us
transfer files, and it can accomplish this between any two machines
using it. But FTP isn’t just a protocol; it’s also a program. Operating
as a protocol, FTP is used by applications. As a program, it’s
employed by users to perform file tasks by hand.
TFTP(Trivial File Transfer Protocol): stripped-down, stock version of
FTP TFTP has no directory-browsing abilities like FTP; it can do
nothing but send and receive files
NFS(Network File System) : is a jewel of a protocol specializing in
file sharing. It allows two different types of file systems to
interoperate.
25. • SMTP(Simple Mail Transfer Protocol) & POP3(Post Office Protocol) :
SMTP is used to send mail while POP3 is used to receive mail
• SNMP(Simple Network Management Protocol):collects and manipulate
valuable network information
• DNS(Domain Name Service):resolves host names to IP addresses.
• DHCP(Dynamic host Configuration Protocol): assigns ip addresses to
hosts.
• LPD (Line Printer Daemon): for printer sharing
26. Host to Host Layer
The main purpose of the Host-to-Host layer is to shield the upper-
layer applications from the complexities of the network.
This layer says to the upper layer, “Just give me your data stream,
with any instructions, and I’ll begin the process of getting your
information ready to send.”
The following sections describe the two protocols at this layer:
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
28. Sequence number : A number used by TCP that puts the data
back in the correct order or retransmits missing or damaged data, a
process called sequencing.
Acknowledgement number: The TCP octet that is expected next
Window: The window size the sender is willing to accept, in octets.
Checksum : The cyclic redundancy check (CRC), performs the
CRC over the header and data fields.
TCP uses a connection oriented communication because unless a
connection between the sender and receiver is created then can
data transmission begins
TCP provides what is called reliable delivery due to the presence of
acknowledgement, sequencing and flow control.
30. UDP
This figure clearly illustrates UDP’s markedly low overhead as
compared to TCP’s hungry usage.
31. Key concepts of Host to Host Protocols
TCP UDP
Sequenced Non-sequenced
Reliable Unreliable
Connection-oriented Connectionless
Virtual circuit Low overhead
Acknowledgments No
acknowledgment
Windowing flow control No windowing or flow
control
32. Port Numbers
A port is a communication channel or endpoint in an Operating
System. The purpose of ports is to uniquely identify different
applications or processes running on a single computer and thereby
enable them to share a single physical connection
. Port number examples for TCP and UDP:
Key Protocols and Port numbers
TCP Telnet
23
SMTP
25
HTTP
80
FTP
21
DNS
53
HTTPS
443
UDP SNMP
161
TFTP
69
DNS
53
34. Version: Identifies the IP version number. There are two versions,
version 4(IPv4) which is most common and version 6(IPv6) which we
will see later.
Time to live: It’s the expiration time of the packet, this prevents a packet
from circulating indefinitely. It is set by the sender of the packet and
reduced by every router on the route to the destination. If it reaches zero
the packet is discarded.
Protocol/Type: Defines the protocol used in the data portion of the IP
packet/datagram.
Header Checksum: for CRC but only for the header
Protocol ICMP EIGRP OSPF IPv6 GRE L2TP IGRP
# 1 88 89 41 47 115 9
35. ICMP
Internet Control Message Protocol (ICMP) works at the
Network layer and is used by IP for many different services.
•ICMP is a management protocol and messaging
service provider for IP.
•Its messages are carried as IP datagrams.
ICMP packets have the following characteristics:
• They can provide hosts with information about network problems.
• They are encapsulated within IP datagrams.
36. ARP
ARP (Address Resolution Protocol) resolves IP addresses to
Ethernet (MAC) addresses i.e. finds the hardware address of a host
from a known IP address.
37. RARP(Reverse-ARP): discovers the identity of the IP address for
diskless machines by sending out a packet that includes its MAC
address and a request for the IP address assigned to that MAC
address.
38. Ethernet Networking
Ethernet is a contention media access method that allows all hosts
on a network to share the same bandwidth of a link.
Ethernet is popular because it’s readily scalable, meaning that it’s
comparatively easy to integrate new technologies, such as Fast
Ethernet and Gigabit Ethernet, into an existing network
infrastructure.
It’s also relatively simple to implement in the first place, and with it,
troubleshooting is reasonably straightforward.
40. When a collision occurs on an Ethernet LAN, the following happens:
• A jam signal informs all devices that a collision occurred.
• The collision invokes a random back-off algorithm.
• Each device on the Ethernet segment stops transmitting for a short
time until the
timers expire.
• All hosts have equal priority to transmit after the timers have
expired.
The following are the effects of having a CSMA/CD network
sustaining heavy collisions:
• Delay
• Low throughput
• Congestion
41. Half and Full Duplex Mode
Half duplex mode enables networking devices to send data or
signals one-way at a time, means both networking devices cannot
send data at the same time.
Eg: its like walkie-talkie
But full-duplex mode unlike half duplex, full duplex mode allow
devices to sending and receiving of data or signals at the same
time.
Eg: its like telephone or cell phone can talk and listen
For the case of Ethernet, full duplex can be used in three situations:
• With a connection from a switch to a host
• With a connection from a switch to a switch
• With a connection from a host to a host using a crossover
cable
43. Ethernet at the Physical Layer
The IEEE 802.3 and original Ethernet Physical layer specifications.
•10Base2- 10Mbps up to 2meters, supports
30hosts on a single segment, uses T-
connectors
•10Base5- 10Mbps up to 5meters, uses
AUI(Attachment Unit Interface)
•10BaseT-10Mbps with each device
connected to a hub or a switch, uses RJ-45
45. Unshielded Twisted-Pair Cable
Speed and throughput: 10 to 1000 Mb/s
Average cost per node: Least expensive
Media and connector size: Small
Maximum cable length: Varies
47. Ethernet cabling is an important discussion, especially if you are
planning on taking the Cisco exams.
Three types of Ethernet cables are available:
• Straight-through cable
• Crossover cable
• Rolled cable
We will look at each in the following sections.
48. Straight-Through Cable
The straight-through cable is used to connect device of the different
type like,
• Host to switch or hub
• Router to switch or hub
Except with router when connected to host.
49. Crossover Cable
The crossover cable can be
used
to connect device of the same
type like
• Switch to switch
• Hub to hub
• Host to host
• Hub to switch
• Router direct to host
50. Rolled Cable
Although rolled cable isn’t used to connect any Ethernet connections
together, you can use a rolled Ethernet cable to connect a host to a
router console serial communication (com) port.
51. Ethernet Cabling
Ethernet cabling is an important discussion, especially if you are
planning on taking the Cisco exams.
Three types of Ethernet cables are available:
• Straight-through cable
• Crossover cable
• Rolled cable
We will look at each in the following sections.
