Rahul Khadse
In one network more than one computer connected with each other through centralized device. They can share files and resources with each other.
LAN
LAN stands for Local Area Network. The scope of the LAN is within one building, one school or within one lab. In LAN (Hub), media access method is used CSMA/CD in which each computer sense the carrier before sending the data over the n/w. if carrier is free then you can transmit otherwise you have to wait or you have to listen. In multiple access each computer have right that they can access each other. If two computers sense the carrier on same time then the collision occur. Each computer, in the network, aware about the collision. Now this stop transmitting and they will use back off algorithm. In which random number is generated. This number or algorithm is used by each computer. Who has short number or small number, he has first priority to transmit the data over the network and other computers will wait for their turn.WAN
WAN stands for Wide Area Network, in which two local area networks are connected through public n/w. it may be through telecommunication infrastructure or dedicated lines. For e.g: - ISDN lines, Leased lines etc.
In which we can use WAN devices and WAN technology. You can also connect with your remote area through existing Internetwork called Internet.
Devices
Hub
Hub is centralized device, which is used to connect multiple workstations. There are two types of Hub: -(i) Active Hub
(ii) Passive Hub
it has no special kind of memory. It simply receives the frame (data) and forwards it to all its nodes except the receiving node. It always performs broadcasting. In case of hub, there is one collision domain and one broadcast domain. In case of hub, the media access method is used CSMA/CD (Carrier Sense Multiple Access/Collision Detection).
(i) Active Hub
In Active hub, it receives the frame regenerate and then forward to all its nodes.
(ii) Passive Hub
In Passive hub, it simply receives the frame and forward to all its connected nodes.
You cannot perform LAN segmentation using hub.
Switch
Switch is also used to connect multiple workstations. Switch is more intelligent than hub. It has special kind of memory called mac address/filter/lookup table. Switch reads mac addresses. Switch stores mac addresses in its filter address table. Switch when receives frame, it reads the destination mac address and consult with its filter table. If he has entry in its filter table then he forwards the frame to that particular mac address, if not found then it performs broadcasting to all its connected nodes.Every port has its own buffer memory. A port has two queues one is input queue and second is output queue. When switch receives the frame, the frame is received in input queue and forward from output queue. So in case of switch there is no chance or place for collisions. In case of switch, the media access method is used CSMA/CA (Carrier Sense Multiple Access/ Collision Avoidance). Switches provide more efficiency, more speed and security.
There are two types of switches: -
(i) Manageable switches (can be configured with console cable).
(ii) Non-manageable switches.
We can perform LAN segmentation by using switches.
Bridge
Bridge is a hardware device, which is used to provide LAN segmentation means it is used for break the collision domain. It has same functionality as performed by switch. We can use bridge between two different topologies. It has fewer ports. Each port has a own buffer memory. It works on Data Link Layer of OSI model. It also read mac address and stores it in its filter table. In case of bridge there is one broadcast domain.
Router
Router is hardware device, which is used to communicate two different networks. Router performs routing and path determination. It does not perform broadcast information. There are two types of routers: -
(i) Hardware Routers are developed by Cisco, HP.
(ii) Software Routers is configured with the help of routing and remote access. This feature is offered by Microsoft. This feature is by default installed, but you have to enable or configure it.
Hardware routers are dedicated routers. They are more efficient.
But in case of software routers, it has less features, slow performance. They are not very much efficient.
Lan Card
Lan card is media access device. Lan card provide us connectivity in the network. There is a RJ45 (Registered Jack) connector space on the Lan card. RJ45 is used in UTP cable. There is another led which is also called heartbeat of Lan card. When any activity occur it may be receiving or transmitting any kind of data. This led start blinking and also tell us the status of lan card.
LAN Topologies
BUS Topology
Cable Type – Coaxial
Connector Type – BNC (Bayonet Neill-Concelman), T type, Terminator
Coaxial – Thick Maximum length – 500 meters
N/w devices 100
Coaxial – Thin Maximum length – 185 meters
Star Topology
Cable type - UTP
Connector type - RJ45
Maximum Length – 100 meters (with proper color coding)
STP (Shielded Twisted Pair)
In case of hub media access method will be CSMA/CD.
Ring Topology
Cable - UTP
Ethernet Family
Speed Base band10 Base 2 200-meter Coaxial cable
10 Base 5 500-meter Thick Coaxial cable
10 Base T 100 meter Twisted Pair (UTP)
10/100(present) Base TX 100 meter UTP
100 Base T4 100 meter UTP 4 Pairs used
100 Base FX up to 4 kms Fiber Optic
1000(Server) Base TX 100 meter UTP
1000 Base FX up to 10 kms Fiber Optic
10000 Base FX Fiber Optic
Color
Green – Green white
Orange – Orange white
Blue – Blue white
Brown – Brown white
Green cable has maximum twists.
Pin Configuration
Hub/Switch PC/Router/Online Printer Uplink port(Hub/Switch)
1 Rx+ Tx+ Tx+
2 Rx- Tx- Tx-
3 Tx+ Rx+ Rx+
4 NC NC NC
5 NC NC NC
6 Tx- Rx- Rx-
7 NC NC NC
8 NC NC NC
Cross Straight
1--- 3 1--- 1
2--- 6 2 ---2
3 ---1 3--- 3
6 ---2 6--- 6
Straight Cable
1 Orange white - Orange white
2 Orange - Orange
3 Green white - Green white
4 Blue - Blue
5 Blue white - Blue white
6 Green - Green
7 Brown white - Brown white
8 Brown - Brown
Cross Cable
1 Orange white - Green white
2 Orange - Green
3 Green white - Orange white
4 Blue - Blue
5 Blue white - Blue white
6 Green - Orange
7 Brown white - Brown white
8 Brown - Brown
RJ45 Connector
IP Address v4
IP address is a 32-bit address. It is divided into four octets. Each octet has 8 bits. It has two parts one is network address and second is host address. in local area network, we can used private IP address, which is provided by IANA (Internet Assigning Numbering Authority). IP addresses are divided into five classes.
Class Range N/w bits Host bits Subnet mask Total IP Valid IP
A 1 – 126 8 24 255.0.0.0 16777216 16777214
B 128 – 191 16 16 255.255.0.0 65536 65534
C 192 – 223 24 8 255.255.255.0 256 254
D 224 – 239 it is reserved for multicast.
E 240 – 255 it is reserved for research/scientific use.
We can use first three classes. IANA provides private IP addresses from first three classes.
Class Private IP Range
A 10.0.0.0 – 10.255.255.255
B 172.16.0.0 – 172.31.255.255
C 192.168.0.0 – 192.168.255.255
One another range that is called APIPA (Automatic Private Internet Protocol Addressing)
169.254.0.0 – 169.254.255.255
We can assign IP address to our computer by two methods: -
(1) Statically or Manually
(2) Dynamically (by using DHCP Server – Dynamic Host Configuration Protocol)
But in case of your computer has no IP address then IP address is assigned to the computer from APIPA range. But communication is not possible when computer has IP address from APIPA range.
Loopback address = 127.0.0.1
Subnet Mask
Subnet mask is also 32-bit address, which tell us how many bits are used for network and how many bits are used for host address.
In Subnet mask Network bits are always 1 and Host bits are always 0.
IP Addresses invalid or reserve IP Addresses
When we are going to assign IP addresses to our computers then we have to follow some rules.
Rules: -
(1) All Host bits cannot be 0 (10.0.0.0), because it represent network address which is reserved for router.
(2) All Host bits cannot be 1 (10.255.255.255), because this is broadcast address of that network (10th network).
(3) All bits cannot be 0 (0.0.0.0), because this address is reserved for Default routing. Default routing is used in case of Stub n/w (means our network has one exit point).
(4) All bits cannot be 1 (255.255.255.255), because this is reserved for Broadcasting.
(5) 127.0.0.1 - This is Loopback address, which is used for self-communication or troubleshooting purpose.
C:\>ipconfig
C:\>ipconfig/all
It shows all detail.
PING – Packet Internet Groper
This command is used to check the connectivity with other computer. Ping is performed with in network or outside of the network. In this process four packets are send to the destination address and four packets are received from the destination address. ICMP (Internet Control Message Protocol) protocol is used for this process.
C:\>Ping 10.0.0.5 –t (for continue ping)
Press Ctrl+C to stop ping.
EMI – Electromagnetic Interference
Posted in: CCNA
