Use the OSI and TCP/IP models and their associated protocols to explain how data flows in a network [1.3]

The Department of Defense (DoD) model is basically a condensed version of the OSI model, It includes four rather than seven, layers:

• Process / application layer
• Host-to-host layer
• Internet layer
• Network access layer

Figure 1.5 shows the comparison of Defense and the OSI reference model model. As you can see, These two similar concepts, but each has a different number of layers with different names.

A variety of protocol at the U.S. Department of Defense combined model process / application layer integration Grate the various activities and responsibilities covered by OSI’s corresponding top three focus Layer (applications, demos and meetings). We will pay close attention to these protocol In the next part of this chapter. Process / application layer protocol definition of node-to-node Communications and applications also control the user interface specifications.

The host-to-host layer parallel functions, OSI’s transport layer to determine the protocols established by the application of transmission services. It solves the problem, such as set up end-to-end reliable communications, and to ensure error-free data. It Deal with packet sequence, and maintain data integrity.

Internet layer corresponds to the OSI network layer protocol specified related Law logic packet transmission across the network. It take care of address Mainframe technology, give them an IP address (Internet Protocol), which deal with the routing Between multiple network packets.

At the bottom of the Defense Department model, the network access layer to monitor the data exchange Between hosts and networks. Equivalent to the data link and physical layer OSI model, the network access layer of the hardware deal with the supervision and to identify protocol Physical transmission of data.

The United States Department of Defense and the OSI model at the design and concept and with similar features, Similar layer. Figure 1.6 shows the TCP / IP protocol suite and its protocols and how to relate to Department of Defense model layer.

In the following sections, we will look at the different protocols in more detail, starting with the Process/Application layer protocols.

Select the components required [1.2]

As the previous goal, we used routers, bridges and switches in a network.
Figure 1.3 shows how the network will look forward to working with all of these network equipment in place. Keep in mind that the router is not only broken the broadcasting domain, every LAN interface, This will break the collision domain as well as.

When you look at Figure 1.3, you notice the center of the stage router discovery, and Each physical network it is connected it? We must use this layout, because Participation of older technologies, bridges and hubs.
At the top network in Figure 1.3, you will find that a bridge was used to connect the hub Router. Bridge decomposition of a collision domain, but all hosts connected to two hubs Still into the same broadcast domain. In addition, the bridge only created two collision Domain, so each device connected to the hub, but have to in the same collision domain for all other equipment Connect to the same hub. This in fact is very poor, but still better than a collision, All hosts several domains. NOTICE else: three centers at the bottom of the connection is also connected to the Router, to create a collision domain and one broadcast domain. This allows network bridging
Looking for a better job indeed!

Here, I’ve placed the LAN switches at the center of the network world so that the routers are connecting only logical networks together. If I implemented this kind of setup, I’ve created virtual LANs (VLANs). But it is really important to understand that even though you have a switched net-
work, you still need a router to provide your inter-VLAN communication, or internetworking.

Obviously, the best network is one that’s correctly configured to meet the business requirements of the company it serves. LAN switches with routers, correctly placed in the network, are the best network design. This book will help you understand the basics of routers and switches, so you can make tight, informed decisions on a case-by-case basis.

Let’s go back to Figure 1.4. Looking at the figure, how many collision domains and broadcast domains are in this internetwork? Hopefully, you answered nine collision domains andthree broadcast domains! The broadcast domains are definitely the easiest to see because only routers break up broadcast domains by default. And since there are three connections, that gives you three broadcast domains. But do you see the nine collision domains? Just in case that’s a no, I’ll explain. The all-hub network is one collision domain; the bridge network equals three collision domains. Add in the switch network of five collision domains—one for
each switch port—and you’ve got a total of nine.

So now that you’ve gotten an introduction to internetworking and the various devices that live in an internetwork, it’s time to head into internetworking models.

Describe the purpose and functions [1.1]

Is likely to have some point you have broken the local employees of a large network into a pile of small Since the user’s response would be reduced to a slow crawl as the network grows and growth and all the growth, your LAN traffic congestion Korea has reached epic proportion. The answer is to break up a really big network into several small things
The so-called network segmentation.

You make use of equipment such as routers, switches and bridges. Figure 1.1 shows the net Korea’s job was split switch, so that each network segment to connect to the switch
It is now a separate collision domain. However, It should be noted that the fact that the network is still a Broadcast domain.

Keep in mind that the hub used in Figure 1.1 just extended the one collision domain from the switch port. Here¡¯s a list of some of the things that commonly cause LAN traffic congestion

• Too many hosts in a broadcast domain
• Broadcast storms
• 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, it is not used in today¡¯s networks.

Now, routers are used to connect together and route network packets from one network
Job to another. Cisco became the de facto standard of routers because of its high-quality
Router products, great selection, excellent service. Routers, by default, to break up a wide range of Actor domain ¡ ª settings of all network equipment sector, to hear all the radio issued
This part. Figure 1.2 shows a small network routers, created the Internet and
Rest of the broadcast domain.

The network in Figure 1.2 shows that each host is connected to its own collision domain,
And routers have been set up two radio domain. And Don ¡ ¯ forget the router to provide
Connected to the wide area network services, as well as! Routers use a number of so-called serial interface WAN connections, specifically, V.35 physical interface of the Cisco routers.

Breaking up a broadcast domain is important because when a host or server sends a net
work broadcast, every device on the network must read and process that broadcast¡ªunle
you¡¯ve got a router. When the router¡¯s interface receives this broadcast, it can respond by
cally saying, ¡ Thanks, but no thanks,¡± and discard the broadcast without forwarding it
to other networks. Even though routers are known for breaking up broadcast domains by
default, it¡¯s important to remember that they break up collision domains as well
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) informa
  IP address).

Four router functions in your network can be listed as follows:

• Packet switching
• Packet filtering
• Internetwork communication
• Path selection

Remember that routers are really switches; they¡¯re actually what we call layer 3 switches
(we’ll talk about layers later in this chapter). Unlike layer 2 switches, which forward or filter
frames, routers (layer 3 switches) use logical addressing and provide what is called packet
switching. Routers can also provide packet filtering by using access lists, and when routers
connect two or more networks together and use logical addressing (IP or IPv6), this is called an internetwork. Last, routers use a routing table (map of the internetwork) to make path
selections and to forward packets to remote networks.

Conversely, switches aren¡¯t used to create internetworks (they do not break up broadcast
domains by default); they¡¯re employed to add functionality to a network LAN. The main
purpose of a switch is to make a LAN work better¡ªto optimize its performance¡ªprovidin
more bandwidth for the LAN¡¯s users. And switches don¡¯t forward packets to other network
as routers do. Instead, they only ¡°switch¡± frames from one port to another within th
switched network.

By default, switches break up collision domains. This is an Ethernet term used to describe
a network scenario wherein one particular device sends a packet on a network segment, forc-
ing every other device on that same segment to pay attention to it. At the same time, a different
device tries to transmit, leading to a collision, after which both devices must retransmit, one
at a time. Not very efficient! This situation is typically found in a hub environment where each
host segment connects to a hub that represents only one collision domain and only one broad-
cast domain. By contrast, each and every port on a switch represents its own collision domain.

Describe how a Network Work [Chapter 1]

.

Welcome to the exciting world of the Internet. This is the first This chapter will really help you understand basic Internet Work focused on how to connect the network using Cisco Routers and switches. First, you need to know in the end what is a Internet. You created a Network when you connect two or more local area network or wide-area network over the router and configure the log iCal network solutions agreement, such as Internet Protocol (IP).

 I also go analyze OSI (OSI) model and describe each Here you are some detail, because you must have a good grasp of its solid foundation, you will be able to set up Based on your knowledge of the network. OSI model has 7 layers are stratified Development of different networks to communicate reliably between the different systems. Because of this book are called upon all the things around the Engineer, it is essential you have to understand the OSI Model Cisco think.

Because there are a number of different types of equipment specified on different levels OSI model, which is very important to understand the many types of cables and connectors All of these devices used to connect networks. We went to the cabling, Cisco equipment, disease cussing how to connect to the router or switch (along with Ethernet LAN technologies) and even How to connect a router or switch console connection