Classful Internet address

Classful Internet address

IP address is 32 bit( dotted decimal notation for IP address)
IP address is a hierarchical address IP address is location based .
The designers are free to choose packet format and sizes addresses delivery techniques and so on..
Nothing is dictated by the hardware.

For  addresses the designers  of TCP IP chose scheme analogous to Physical network addressing in which each Host on the internet is assigned 32 bit integer address called  its internet address or IP address
Integer are chosed carefully to make routing efficient.
IP address encodes the identification of the network to which a host attaches as well as identification of a unique host. EA is a pair ,net IDand  host ID .net ID identifies  the network and host ID identifies a host on that network each address is a pair (net ID ,host ID)
Net ID identifies a network
host ID identifies a host on that network
The partition into prefix and suffix is not uniform throughout the entire internet because the designer  did not specify a single boundary

In the original addressing scheme which is known as class full each  IP address had  one of the first three form.

In the classful addressing scheme each address is said to be self identify because the boundary between prefix and suffix can be computed from the address alone without reference to external information
Subnet and supernet (classless addresses )extensions
A unique prefix for each physical network would exhaust the address space quickly consequently an Addressing  extension was developed to conserve network prefix known as subnet addressing scheme allows multiple physical networks to share a prefix.

A second extension was devised that ignored the classful heirarchy and allowed the division b/w perfix and suffix to occur at arbitary point called classles addressing or supernetting .
The scheme allows more complete utilization of the address space

Q.I.a.What is meant by subnet addressing?(5 mark)[B. Tech Degree VII Semester Special Supplementary Examination June 2012 CS/IT 703 ADVANCED COMPUTER NETWORKS (2006 Scheme)]
Q.I.b.With the help of a neat diagram show the original classful IP addressing scheme.(5 mark)[B. Tech. Degree VII Semester Examination November 2012 CS/IT 703 ADVANCED COMPUTER NETWORKS (2006 Scheme)]

VLAN

VLAN
A set  of ports on an ethernet switch that are configured by the network manager to be part of a single broadcast domain.
 Vlan allows a manager to configure the switch to operate like Several smaller switches.

A manager can use virtual LAN to separate computer according to policies

A manager can create one or more virtual LAN by specifying which computer attached to which virtual LAN
EG:

• VLAN  for employees
• VLAN  for visitors

Each virtual LAN define a broadcast domain which means that when a computer send a broadcast packet ,the packet only delivered to the set of computer in the same VirtualLAN .

Virtual LAN is treated exactly like a separate physical network.
Virtual LAN technology emulate a set of independent physical network
A computer in a given virtual LAN share broadcast and multicast access on a given virtualLAN  and does not spread to other virtualLAN ,just like a separate physical network broadcast and multicast send


Q.III.a.Write short notes on VLAN. (8marks)[B. Tech. Degree VII Semester Examination November 2012 CS/IT 703 ADVANCED COMPUTER NETWORKS (2006 Scheme)]

Extending an ethernet with bridges

Extending an ethernet with bridges
Adaptive bridge

• Connecting 2 Ethernet with bridges in superoir to connecting them in repeater a hub because bridges operate on packet rather than electrical signal
• bridges
• do not replicate noise
• do not replicate error
• donot replicate malformed frames
• validates the frame before transmitting to other the other network
• hides the details of interconnections : set of bridges segmentsact as like a single ethernet
• and Ethernet follow CSMNCD rules
• make intelligent decisions about frame to forward

Collision and propagation delays on one segment remain isolated from those on the other

Bridges network are  classified as transparent

Adaptive bridge/learning bridge
Bridges makes intelligent decision about frame to forward
An adaptive bridge consist of a computer with two Ethernet interfaces software in adaptive bridge keep two address stack

when a frame srrives from ethernet \(E_1\), the adaptive bridge add a 48 bit Ethernet source address to list associated with \(E_1\)
similiarly
when a frame arrive from \(E_2 \) to bridge adds the source address to list associated with \(E_2\)
Thus adaptive bridge will learn which machine lie on \(E_1\) and which lie on \(E_2\)

In bridge packet forwarding is used by softwares
bridge work only for half duplex mode
Switch
In this packet forwarding using by ASIC(Application Specified Integrated Circuits)
Operates in comparatively higher speed than bridge
superior than bridge
Method of switching in switching is store and forward ,cut through switching or fragment free
Normally switches has more ports than a bridge
Switches operates in half duplex mode or full duplex mode

Ethernet Hardware Address

Ethernet Hardware Address
Ethernet defines 48 bit addressing scheme >Each computer attached to an Ethernet network is assigned a unique 48 bit number known as its Ethernet address,Ethernet hardware address manufactures purchase a blocks of ethernet address and assign them in sequence as they manufactures ethernet interface hardware,Thus no two hardware interface have the same ethernet address.
Properties of Ethernet address
→physical addresses are associated with ethernet interface hardware
→moving the hardware interface to a new machine or replacing a hardware interface that has failed changes the machine physical address

Ethernet frame format

Ethernet should be thought of as a link level connection among machine thus it makes sense to view the data transmitted as a frame

→Ethernet frame are variable length
with no frame smaller than 64 octet or larger than 1518
64<=frame<=1518→frame length
In a packet switching network each frame contain a field that contain addressing of destination

The preamble consist of 64 bits(8 octet) of alternating 0's and 1's to help receiving interfaces synchronize
CRC
4 octet→32bit CRC helps the interface detect transmission errors
Frame type
16bit integer help to identify the type of data being carried in the frame
Ethernet frame is self identifying which means that os can determine the type protocol software module should process the frame
the chief advantages of self identifying is they allow multiple protocol to be intermixed on the same physical network without interference


Q.I.a.Explain the Ethernet addressing scheme.(5 mark)[B. Tech. Degree VII Semester Examination November 2012 CS/IT 703 ADVANCED COMPUTER NETWORKS (2006 Scheme)]

Properties of Ethernet

Properties of Ethernet
Shared bus technology
Ethernet was designed to be shared bus technology that support braodcast
Shared bus
The topology is called a shared bus becuase all station to be a single shared communication channel
broadcast technology
It is called broadcast technology because all station receive energy transmission making it possible to transmit a packet to all station at same time
Best effort delivery
Ethernet is called a best effort delivery mechanism because the hardware provides no information to sender about whether the packet was delivered if destination station happen to be power down packet to it will be most
Acces control is distributed
Ethernet access control is distributed because unlike some network technologies Ethernet has no central authority to grant access

Working
The Ethernet access control is called carrier sense multiple access with collision detection
It is CSMA because multiple machine can access an Ethernet simultaneously and each machine determine whether the network is idle by sending whether a carrier wave is present

Exponential backoff
Waiting timing doubles if it is found the busy channel when try to resend .It works on data links layer data is transmitted as frame

Ethernet Techology

Ethernet is a name given to a popular PACKET SWITCH LAN tehnology

IEEE released a compatible version of the standard using standard number 802.3
.It has become most popular LAN technology
Initially it is called 10 base 5 ,it uses a co-axial cable
10 base for 10Mbps speed
5 stand for 500 meter long
it s called thicknet
It has less electrical interference
A resistor is added between the center wire and shield at each end to prevent reflection of electrical signals
Each connection to an original Ethernet uses two major electrical components
1.Transciever

2.Ahost interface card or host adapter
Transciever
Transciever connect to the center wire and braided shield on the cable sensing sending signals on the ether
A host interface card (host adapter )
A host interface card play into the computer bus(eg:motherboard) and connects to the transciever
Tranceiver
A transceiver is a small piece of hardware usually found physically adjacent to the ether .In addition to the analog hardware that sense and control electrical signal on the ether ,a transceiver contain digital circuitry that allows it to communicate with digital computer

The transceiver senses when ether is used and translate analog electrical signal on the ether to and from digital form AUI(Attached Unit Interface) cable (initially transceiver cable) contain many wires ,AUI connect the transceiver to an adapter board in host computer .The wire carry the electrical power needed to operate the transceiver the signal that control the transceiver operation and the contents of  packet being sent or received

Ethernet

Host Interface(It can be complex device)
each host interface control the operation of one transceiver according to instruction received from computer software
To the OS software Host ,Host interface appears to be input output device
It reports status information
It accept basic data transfer instruction from computer
It control the transceiver to carry them out
It interrupt when the task has been completed

Thin wire Ethernet
10 base 5 →thicknet
10 base 2→thin wirenet /thinnet
It has BNC connectors can connect a computer without using tools
Adavantages
Co-axial cabe is thinner
less expensive
more flexible
To add a new computer one only needs to link it into the chain
This scheme works well for when many computer occupy a single room
replaced costly transceiver hardware with specially high speed digital circuits
Provide a direct connection computer the network (easy to connect and disconnect)
manufacture of small computer and workstation find thinnet an specially attractive scheme because they can integrate ethernet hardware into single board computer and mount connection directly on the back of the computer
Disadvantages
if a user disconnect the ethernet it prevent all machine on the ether from communicating
electrical interface is highly affected
it cover somewhat shorter distance
only fewer computer per network than thick ethernet

Twisted pair network
Ethernet without electrical shielding of a co-axial cable
Now commonly used
Thin,low cost to instal
simple cable yet not affected byelectrical interference
4 pair of wires (8 wires)
It uses category 5 cabling
It is 10 base -T ethernet
T stand for twisted pair

It uses a central hub maximum distance from one computer to hub is 100 meter
It protect other computer
If a user disconnect one computer on the network
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Fast Ethernet
To overcome the throughput limitation of ethernet engineers designed a new version of ethernet that operate an order of magnitude faster ,Initially known as 100 base T
The technology is usually fast ethernet
Fast Ethernet uses category 5 twisted pair wiring
the same used for 10 base T
TWO facts of fast Ethernet
1)Although computer have become faster few computer system transmit data at sustained rate of 100Mbps

2)The 100 baseT standard did not change other parts of the Ethernet standard .In particular the maximum packet size remain same for 10baseT

These facts shows that fast Ethernet is not optimized to provide the highest possible through put between a pair of computer
The design is optimized to allow more station and more total traffic

10/100 Ethernet
The technology which is known as dual speed Ethernet or 10/100 Ethernet
is available for computer interfaces as well as for hubs
It has become extremely popular
Dual speed devices are especially helpful during transition of 10Mbps technology to 100Mbps technology

Gigabit Ethernet
1000 base-T
high throughput rate make it popular for using backbone network
Disadvatages
high data rates does have slight disadvantages -It make more susceptible to electrical interference
High cost

Q.III.b.Fast and gigabit Ethernet (ii) 10/100/1000 Ethernet (7mark)[B. Tech. Degree VII Semester Examination November 2012 CS/IT 703 ADVANCED COMPUTER NETWORKS (2006 Scheme)]

Describe LAN and WAN technologies

Describe LAN and WAN technologies
These are the privately owned network within a building or campus of upto few kilometer in size .They have high speed
In LAN each computer usually contain a device known as NIC(network interface card ) that contain the machine directly to the network.The network itself need not contain much intelligent to generate and receive the complete electrical signal
WAN
It is also long hand network provide over long distances it can span a continent or can join computer across an ocean .it operate at slower speed than LAN and has greater delay between connection The collection of machine intended for running user program are called hosts are connected by subnet the job of subnet is carry messages from host to host
In WAN the subnet consist of two distinct components
1. Transmission lines
2.Switching elements