CEN-444
Networks Structure And Protocols
Internet protocol
And
Routing
Mohammed Saleem Bhat
m.bhat@mu.edu.sa
Computer Engineering and Networks, College of Engineering , Majmaah University
Routing
Outline:

IP: Internet Protocol.

IP Addressing/ Subnet Mask.

ARP: Address Resolution Protocol / IPV6

Routing

VLANS: (Virtual LAN)

TCP/UDP : Transmission Control Protocol / User Datagram Protocol

NATing

SNMP : Simple Network Management Protocol

VPN: Virtual Private Networks .
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IP as a Routed Protocol
IP is a connectionless, unreliable,
best-effort delivery protocol.
IP accepts whatever data is passed
down to it from the upper layers
and forwards the data in the form
of IP Packets.
All the nodes are identified using
an IP address.
Packets are delivered from the
source to the destination using IP
address
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Internet Protocol
Packet Propagation
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Internet Protocol
IP Address
IP address is for the INTERFACE of a host. Multiple
interfaces mean multiple IP addresses, i.e., routers.
32 bit IP address in dotted-decimal notation for ease of
reading, i.e., 193.140.195.66
Address 0.0.0.0, 127.0.0.1 and 255.255.255.255 carries
special meaning.
IP address is divided into a network number and a host
number.
Also bits in Network or Host Address cannot be all 0 or 1.
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IP Address
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IP Address
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IP Address
Class A : Address begins with bit 0. It has 8 bit network
number (range 0.0.0.0-to-127.255.255.255), 24 bit host
number.
Class B : Address begins with bits 10. It has 16 bit
network number (range 128.0.0.0-to-191.255.255.255), 16
bit host number.
Class C : Address begins with bits 110. It has 24 bit
network number (range 192.0.0.0-to-223.255.255.255), 8
bit host number.
Class D : Begins with 1110, multicast addresses (224.0.0.0to-239.255.255.255)
Class E : Begins with 11110, unused
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
Subnet Mask
Consider IP address = 192.168.2.25
First few bits (left to right) identify network/subnet
Remaining bits identify host/interface
Number of subnet bits is called subnet mask, e.g.
Subnet IP Address range is 192.168.2.0 – 192.168.2.255
or Mask = 255.255.255.0
Subnet IP Address range is 192.168.2.0 – 192.168.2.15
or Mask = 255.255.255.240
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IP Address, Subnet Mask and
Gateway
IP Address and Subnet Mask define the Subnet
For Example IP address 172.31.1.0 and Subnet Mask of
255.255.240.0 means that the subnet address ranges from
172.31.0.0 to 172.31.15.255
Another notation is 172.31.1.0/28
The first Address is the Network Address and the last
Address is the Broadcast Address. They are reserved and
cannot be assigned to any node.
The Gateway Address is the Address of the router where
the packet should be sent in case the destination host does
not belong to the same subnet
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Internet Protocol
IP Configuration of an Interface
Static
DHCP
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Internet Protocol
ARP
ARP (Address Resolution Protocol) is used in Ethernet
Networks to find the MAC address of a node given its IP
address.
Source node (say 192.168.2.32) sends broadcast message
(ARP Request) on its subnet asking ``Who is
192.168.2.33’’.
All computers on subnet receive this request
Destination responds (ARP Reply) since it has
192.168.2.33
Provides its MAC address in response
Computer Engineering and Networks, College of Engineering , Majmaah University
Internet Protocol
IPv6
Internet Protocol Version 4 is the most popular protocol
in use today, although there are some questions about its
capability to serve the Internet community much longer.
IPv4 was finished in the 1970s and has started to show its
age.
The main issue surrounding IPv4 is addressing—or, the
lack of addressing—because many experts believe that we
are nearly out of the four billion addresses available in
IPv4.
Although this seems like a very large number of
addresses, multiple large blocks are given to government
agencies and large organizations.
IPv6 could be the solution to many problems posed by
IPv4
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Internet Protocol
IPv6
IPv6 uses 128 bit address instead of 32 bit address.
The IPv6 addresses are being distributed and are
supposed to be used based on geographical location.
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Routing
ROUTING
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Routing
Router
A router is a device that determines the next network
point to which a packet should be forwarded toward its
destination
Allow different networks to communicate with each other
A router creates and maintain a table of the available
routes and their conditions and uses this information to
determine the best route for a given packet.
A packet will travel through a number of network points
with routers before arriving at its destination.
There can be multiple routes defined. The route with a
lower weight/metric will be tried first.
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Routing
Routing
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Routing
Routing Protocols
Static Routing
Dynamic Routing
IGP (Interior Gateway Protocol): Route data within an Autonomous
System
RIP (Routing Information Protocol)
RIP-2 (RIP Version 2)
OSPF (Open Shortest Path First)
IGRP (Interior Gateway Routing Protocol)
EIGRP (Enhanced Interior Gateway Routing Protocol)
IS-IS
EGP (Exterior Gateway Protocol): Route data between Autonomous
Systems
BGP (Border Gateway Protocol)
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Internetworking Devices
Internetworking Devices
Device
Description
Hub
Hubs are used to connect multiple users to a single physical device,
which connects to the network. Hubs and concentrators act as
repeaters by regenerating the signal as it passes through them.
Bridge
Bridges are used to logically separate network segments within the
same network. They operate at the OSI data link layer (Layer 2) and
are independent of higher-layer protocols.
Switch
Switches are similar to bridges but usually have more ports.
Switches provide a unique network segment on each port, thereby
separating collision domains. Today, network designers are replacing
hubs in their wiring closets with switches to increase their network
performance and bandwidth while protecting their existing wiring
investments.
Router
Routers separate broadcast domains and are used to connect
different networks. Routers direct network traffic based on the
destination network layer address (Layer 3) rather than the
workstationand
dataNetworks,
link layerCollege
or MACofaddress.
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Engineering , Majmaah University
VLAN
VLAN
Computer Engineering and Networks, College of Engineering , Majmaah University
VLAN
VLANs
VLANs (Virtual LAN) enable network managers to group
users logically (based on functions, project teams or
applications) rather than by physical location.
Traffic can only be routed between VLANs.
VLANs provide the segmentation traditionally provided
by physical routers in LAN configuration.
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VLAN
VLANs and Inter VLAN Routing
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VLAN
Advantages of Using VLANs
Broadcast Control— Just as switches physically isolate
collision domains for attached hosts and only forward traffic
out a particular port, VLANs provide logical bridging
domains that confine broadcast and multicast traffic to the
VLANs.
Security— If you do not allow routing in a VLAN, no users
outside of that VLAN can communicate with the users in the
VLAN and vice versa. This extreme level of security can be
highly desirable for certain projects and applications.
Performance— You can assign users that require highperformance or isolated networking to separate VLANs.
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TCP/UDP
TCP/UDP
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TCP/UDP
TCP/UDP
Transport Layer Protocol
TCP is connection Oriented (uses checksum and
acknowledgment)
UDP is Connectionless
Both use the concept of Connection Port Number (16 Bit
Source Port Number and Destination Port Number)
Standard Applications have standard Port Numbers
(Email 25, Telnet 23, FTP 20 & 21, SSH 22)
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Natting
NATTING
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Natting
Private vs Public IP Addresses
Whatever connects directly into Internet must have public
(globally unique) IP address
There is a shortage of public IPv4 address
So Private IP addresses can be used within a private
network
Three address ranges are reserved for private usage
10.0.0.0/8
172.16.0.0/16 to 172.31.0.0/16
192.168.0.0/24 to 192.168.255.0/24
A private IP is mapped to a Public IP, when the machine
has to access the Internet
Computer Engineering and Networks, College of Engineering , Majmaah University
Natting
NAT
NAT (Network Address Translation) Maps Private IPs to
Public IPs
It is required because of shortage of IPv4 Address
H1
H3
H2
10.0.1.2
10.0.1.3
Private network 1
H5
213.168.112.3
10.0.1.1
H4
10.0.1.2
10.0.1.1
10.0.1.3
Private network 2
Internet
Router/NAT
128.195.4.119
Router/NAT
128.143.71.21
Computer Engineering and Networks, College of Engineering , Majmaah University
Natting
NAT
Static NAT : Maps unique Private IP to unique Public IP
Dynamic NAT : Maps Multiple Private IP to a Pool of
Public IPs (Port Address Translation : Maps a Public IP
and Port Number to a service in Private IP)
Source = 128.143.71.21
Source port = 3200
Source = 10.0.1.2
Source port = 2001
Private address: 10.0.1.2
H1
Private network
Private address: 10.0.1.3
H2
Source = 10.0.1.3
Source port = 1090
128.143.71.21
Internet
NAT
Source = 128.143.71.21
Destination = 4444
Computer Engineering and Networks, College of Engineering , Majmaah University
SNMP
SNMP
Computer Engineering and Networks, College of Engineering , Majmaah University
SNMP
Simple Network Management
Protocol
SNMP is a framework that
provides facilities for managing
and
monitoring
network
resources on the Internet.
Components of SNMP:
SNMP agents
SNMP managers
Management
Information
Bases (MIBs)
SNMP protocol itself
SNMP agent
SNMP
manager
SNMP
protocol
messages
SNMP agent
SNMP agent
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SNMP
SNMP
SNMP
is
based
on
the
manager/agent model consisting
of a manager, an agent, a
database
of
management
information, called as MIB.
The manager provides the
interface between the human
network manager and the
management system.
The agent provides the interface
between the manager and the
physical
device(s)
being
managed.
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SNMP
SNMP
SNMP uses five basic messages (GET, GET-NEXT, GETRESPONSE, SET, and TRAP) to communicate between the manager
and the agent.
The GET and GET-NEXT messages allow the manager to request
information for a specific variable. The agent, upon receiving a GET
or GET-NEXT message, will issue a GET-RESPONSE message to the
manager with either the information requested or an error indication
as to why the request cannot be processed.
A SET message allows the manager to request a change be made to
the value of a specific variable in the case of an alarm remote that will
operate a relay. The agent will then respond with a GET-RESPONSE
message indicating the change has been made or an error indication
as to why the change cannot be made.
The TRAP message allows the agent to spontaneously inform the
manager of an ‘important’ event.
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VPN
VPN
Computer Engineering and Networks, College of Engineering , Majmaah University
VPN
VPN
VPN is a private connection between two systems or
networks over a shared or public network (typically
Internet).
VPN technology lets an organization securely extend its
network services over the Internet to remote users,
branch offices, and partner companies.
In other words, VPN turns the Internet into a simulated
private WAN.
VPN is very appealing since the Internet has a global
presence, and its use is now standard practice for most
users and organizations.
Computer Engineering and Networks, College of Engineering , Majmaah University
VPN
VPN
Computer Engineering and Networks, College of Engineering , Majmaah University
VPN
How VPN Works
To use the Internet as a private Wide Area Network,
organizations may have to address two issues :
First, networks often communicate using a variety of
protocols, such as IPX and NetBEUI, but the Internet can
only handle TCP/IP traffic. So VPN may need to provide
a way to pass non-TCP/IP protocols from one network to
another.
Second data packets traveling the Internet are transported
in clear text. Therefore, anyone who can see Internet
traffic can also read the data contained in the packets.
This is a problem if companies want to use the Internet to
pass important, confidential business information.
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VPN
How VPN Works
VPN overcome these obstacles by using a strategy called
Tunneling. Instead of packets crossing the Internet out in
the open, data packets are fist encrypted for security, and
then encapsulated in an IP packet by the VPN and
tunneled through the Internet.
The VPN tunnel initiator on the source network
communicates with a VPN tunnel terminator on the
destination network. The two agree upon an encryption
scheme, and the tunnel initiator encrypts the packet for
security.
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VPN
Advantages of Using VPN
VPN technology provides many benefits. Perhaps the
biggest selling point for VPN is cost savings. One can
avoid having to purchase expensive leased lines to branch
offices or partner companies. On another cost-related
note, you can evade having to invest in additional WAN
equipment and instead leverage your existing Internet
installation.
Another benefit of VPN is that it is an ideal way to handle
mobile users.
Computer Engineering and Networks, College of Engineering , Majmaah University