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Types of communication Method

What is Unicast?

Unicast is a type of communication where data is sent from one computer to another computer.

In Unicast type of communication, there is only one sender, and one receiver.

Example:

1) Browsing a website. (Web-server is the sender and your computer is the receiver.)

2) Downloading a file from a FTP Server. (FTP Server is the sender and your computer is the receiver.)

What is Multicast?

Multicast is a type of communication where multicast traffic addressed for a group of devices on the network. IP multicast traffic are sent to a group and only members of that group receive and/or process the Multicast traffic.

Devices which are interested in a particular Multicast traffic must join to that Multicast group to receive the traffic. IP Multicast Groups are identified by Multicast IP Addresses (IPv4 Class D Addresses)

In Multicast, the sender transmit only one copy of data and it is delivered and/or processed to many devices (Not as delivered and processed by all devices as in Broadcast) who are interested in that traffic.

Example : Multicast Windows Deployment Services (WDS) OS deployment traffic, IP TV etc

What is Broadcast?

Broadcast is a type of communication where data is sent from one computer once and a copy of that data will be forwarded to all the devices.

In Broadcast, there is only one sender and the data is sent only once. But the Broadcast data is delivered to all connected devices.

Switches by design will forward the broadcast traffic and Routers by design will drop the broadcast traffic. In other words, Routers will not allow a broadcast from one LAN to cross the Router and reach another Network Segment. The primary function of a Router is to divide a big Broadcast domain to Multiple smaller Broadcast domain.

Example: ARP Request message, DHCP DISCOVER Message

What is CSMA/CD ?

Types of Router Memory

Routing Protocols And Types of Routing?

Routing Protocols

Routing protocols were created for routers. These protocols have been designed to allow the exchange of routing tables, or known networks, between routers. There are a lot of different routing protocols, each one designed for specific network sizes.

Two main types of routing:

ü  Static routing

ü  Dynamic routing

The router learns about remote networks from neighbor routers or from an administrator. The router then builds a routing table. If the network is directly connected then the router already knows how to get to the network. If the networks are not attached, the router must learn how to get to the remote network with either static routing (administrator manually enters the routes in the router's table) or dynamic routing (happens automatically using routing protocols like EIGRP,OSPF,etc.).

The routers then update each other about all the networks they know. If a change occurs e.g a router goes down, the dynamic routing protocols automatically inform all routers about the change. If static routing is used, then the administrator has to update all changes into all routers and therefore no routing protocol is used.

Only Dynamic routing uses routing protocols, which enable routers to:

• Dynamically discover and maintain routes
• Calculate routes
• Distribute routing updates to other routers
• Reach agreement with other routers about the network topology

Statically programmed routers are unable to find  routes, or send routing information to other routers. They send data over routes defined by the network Admin.

A Stub network is so called because it is a dead end in the network. There is only one route in and one route out and, because of this, they can be reached using static routing, thus saving valuable bandwidth.

Dynamic Routing Protocols

There are 3 types of Dynamic routing protocols, these are differ by  the way that discover and make calculations about routes;

1. Distance Vector

2. Link State

3. Hybrid

• Distance Vector routers find the best path from information send from neighbors
• Link State routers each have a copy of the entire network map
• Link State routers find best routes from this local map

The Table below shows the main characteristics of a few different types of dynamic routing protocols:

Routing Protocols
Features	RIPv1	RIPv2	IGRP	OSPF	EIGRP
Classful/Classless Metric Time Period Administrative Distace(AD) Type	Classful Hop 30 sec 120 Distance vector	Classless Hop 30 sec 120 Distance vector	Classful Composite (90 sec) 90 sec 100 Distance vector	Classless Cost None 110 Link state	Classless Composite (30 sec) 30 sec Internal:  90 External: 170 Hybrid

You can also classify the routing protocols in terms of their location on a network. For example, routing protocols can exist in, or between, autonomous systems.

All CISCO Certifications.

CISCO Systems.

Cisco Systems, Inc. is an American multinational technology company headquartered in San Jose, California, that designs, manufactures and sells networking equipment It is considered to be the biggest networking company in the world. The stock was added to the Dow Jones Industrial Average on June 8, 2009, and is also included in the S&P 500 Index, the Russell 1000 Index,NASDAQ-100 Index and the Russell 1000 Growth Stock Index.

Type	Public
Traded as	NASDAQ: CSCO Dow Jones Industrial Average Component S&P 500 Component NASDAQ-100 Component
Industry	Networking equipment
Founded	December 1984; 31 years ago San Francisco, California, U.S.
Founders	Leonard Bosack Sandy Lerner
Headquarters	San Jose, California, U.S.
Coordinates
Area served	Worldwide
Key people	John Chambers (Executive Chairman) Chuck Robbins (CEO)
Products	Networking Device Network Management Cisco IOS and NX-OS Software Interface and Module Optical networking Storage area networks Wireless, Telepresence, VOIP, Security Datacenter List of Cisco Products
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