ccna module 5

Overview



Even though each LAN is unique, there are many design aspects that are common to all LANs. For example, most LANs follow the same standards and use the same components. This module presents information on elements of Ethernet LANs and common LAN devices.

There are several types of WAN connections. They range from dial-up to broadband access and differ in bandwidth, cost, and required equipment. This module presents information on the various types of WAN connections.

This module covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND 640-811 exams.

Students who complete this module should be able to perform the following tasks:

* Identify characteristics of Ethernet networks
* Identify straight-through, crossover, and rollover cables
* Describe the function, advantages, and disadvantages of repeaters, hubs, bridges, switches, and wireless network components
* Describe the function of peer-to-peer networks
* Describe the function, advantages, and disadvantages of client-server networks
* Describe and differentiate between serial, ISDN, DSL, and cable modem WAN connections
* Identify router serial ports, cables, and connectors
* Identify and describe the placement of equipment used in various WAN configurations

5.1
Cabling LANs
5.1.1
LAN physical layer



This page describes the LAN physical layer.

Various symbols are used to represent media types. Token Ring is represented by a circle. FDDI is represented by two concentric circles and the Ethernet symbol is represented by a straight line. Serial connections are represented by a lightning bolt.

Each computer network can be built with many different media types. The function of media is to carry a flow of information through a LAN. Wireless LANs use the atmosphere, or space, as the medium. Other networking media confine network signals to a wire, cable, or fiber. Networking media are considered Layer 1, or physical layer, components of LANs.

Each type of media has advantages and disadvantages. These are based on the following factors:

* Cable length
* Cost
* Ease of installation
* Susceptibility to interference

Coaxial cable, optical fiber, and space can carry network signals. This module will focus on Category 5 UTP, which includes the Category 5e family of cables.

Many topologies support LANs, as well as many different physical media. Figure shows a subset of physical layer implementations that can be deployed to support Ethernet.

The next page explains how Ethernet is implemented in a campus environment.
5.1
Cabling LANs
5.1.2
Ethernet in the campus



This page will discuss Ethernet.

Ethernet is the most widely used LAN technology. Ethernet was first implemented by the Digital, Intel, and Xerox group (DIX). DIX created and implemented the first Ethernet LAN specification, which was used as the basis for the Institute of Electrical and Electronics Engineers (IEEE) 802.3 specification, released in 1980. IEEE extended 802.3 to three new committees known as 802.3u for Fast Ethernet, 802.3z for Gigabit Ethernet over fiber, and 802.3ab for Gigabit Ethernet over UTP.

A network may require an upgrade to one of the faster Ethernet topologies. Most Ethernet networks support speeds of 10 Mbps and 100 Mbps.

The new generation of multimedia, imaging, and database products can easily overwhelm a network that operates at traditional Ethernet speeds of 10 and 100 Mbps. Network administrators may choose to provide Gigabit Ethernet from the backbone to the end user. Installation costs for new cables and adapters can make this prohibitive.

There are several ways that Ethernet technologies can be used in a campus network:

* An Ethernet speed of 10 Mbps can be used at the user level to provide good performance. Clients or servers that require more bandwidth can use 100-Mbps Ethernet.
* Fast Ethernet is used as the link between user and network devices. It can support the combination of all traffic from each Ethernet segment.
* Fast Ethernet can be used to connect enterprise servers. This will enhance client-server performance across the campus network and help prevent bottlenecks.
* Fast Ethernet or Gigabit Ethernet should be implemented between backbone devices, based on affordability.

The media and connector requirements for an Ethernet implementation are discussed on the next page.
5.1
Cabling LANs
5.1.3
Ethernet media and connector requirements



This page provides important considerations for an Ethernet implementation. These include the media and connector requirements and the level of network performance.

The cables and connector specifications used to support Ethernet implementations are derived from the EIA/TIA standards. The categories of cabling defined for Ethernet are derived from the EIA/TIA-568 SP-2840 Commercial Building Telecommunications Wiring Standards.

Figure compares the cable and connector specifications for the most popular Ethernet implementations. It is important to note the difference in the media used for 10-Mbps Ethernet versus 100-Mbps Ethernet. Networks with a combination of 10- and 100-Mbps traffic use Category 5 UTP to support Fast Ethernet.

The next page will discuss the different connection types.
5.1
Cabling LANs
5.1.4
Connection media



This page describes the different connection types used by each physical layer implementation, as shown in Figure . The RJ-45 connector and jack are the most common. RJ-45 connectors are discussed in more detail in the next section.

The connector on a NIC may not match the media to which it needs to connect. As shown in Figure , an interface may exist for the 15-pin attachment unit interface (AUI) connector. The AUI connector allows different media to connect when used with the appropriate transceiver. A transceiver is an adapter that converts one type of connection to another. A transceiver will usually convert an AUI to an RJ-45, a coax, or a fiber optic connector. On 10BASE5 Ethernet, or Thicknet, a short cable is used to connect the AUI with a transceiver on the main cable.

The next page will discuss UTP cables.
5.1
Cabling LANs
5.1.5
UTP implementation



This page provides detailed information for a UTP implementation.

EIA/TIA specifies an RJ-45 connector for UTP cable. The letters RJ stand for registered jack and the number 45 refers to a specific wiring sequence. The RJ-45 transparent end connector shows eight colored wires. Four of the wires, T1 through T4, carry the voltage and are called tip. The other four wires, R1 through R4, are grounded and are called ring. Tip and ring are terms that originated in the early days of the telephone. Today, these terms refer to the positive and the negative wire in a pair. The wires in the first pair in a cable or a connector are designated as T1 and R1. The second pair is T2 and R2, the third is T3 and R3, and the fourth is T4 and R4.

The RJ-45 connector is the male component, which is crimped on the end of the cable. When a male connector is viewed from the front, the pin locations are numbered from 8 on the left to 1 on the right as seen in Figure .

The jack, as seen in Figure , is the female component in a network device, wall outlet, or patch panel. Figure shows the punch-down connections at the back of the jack where the Ethernet UTP cable connects.

For electricity to run between the connector and the jack, the order of the wires must follow T568A or T568B color code found in the EIA/TIA-568-B.1 standard, as shown in Figure . To determine the EIA/TIA category of cable that should be used to connect a device, refer to the documentation for that device or look for a label on the device near the jack. If there are no labels or documentation available, use Category 5E or greater as higher categories can be used in place of lower ones. Then determine whether to use a straight-through cable or a crossover cable.

If the two RJ-45 connectors of a cable are held side by side in the same orientation, the colored wires will be seen in each. If the order of the colored wires is the same at each end, then the cable is a straight-through, as seen in Figure .

In a crossover cable, the RJ-45 connectors on both ends show that some of the wires are connected to different pins on each side of the cable. Figure shows that pins 1 and 2 on one connector connect to pins 3 and 6 on the other.

Figure shows the guidelines that are used to determine the type of cable that is required to connect Cisco devices.

Use straight-through cables for the following connections:

* Switch to router
* Switch to PC or server
* Hub to PC or server

Use crossover cables for the following connections:

* Switch to switch
* Switch to hub
* Hub to hub
* Router to router
* PC to PC
* Router to PC

Figure illustrates how a variety of cable types may be required in a given network. The category of UTP cable required is based on the type of Ethernet that is chosen.

The Lab Activity shows the termination process for an RJ-45 jack.

The Interactive Media Activities provide detailed views of a straight-through and crossover cable.

The next page explains how repeaters work.
5.1
Cabling LANs
5.1.6
Repeaters



This page will discuss how a repeater is used on a network.

The term repeater comes from the early days of long distance communication. A repeater was a person on one hill who would repeat the signal that was just received from the person on the previous hill. The process would repeat until the message arrived at its destination. Telegraph, telephone, microwave, and optical communications use repeaters to strengthen signals sent over long distances.

A repeater receives a signal, regenerates it, and passes it on. It can regenerate and retime network signals at the bit level to allow them to travel a longer distance on the media. Ethernet and IEEE 802.3 implement a rule, known as the 5-4-3 rule, for the number of repeaters and segments on shared access Ethernet backbones in a tree topology. The 5-4-3 rule divides the network into two types of physical segments: populated (user) segments, and unpopulated (link) segments. User segments have users' systems connected to them. Link segments are used to connect the network repeaters together. The rule mandates that between any two nodes on the network, there can only be a maximum of five segments, connected through four repeaters, or concentrators, and only three of the five segments may contain user connections.

The Ethernet protocol requires that a signal sent out over the LAN reach every part of the network within a specified length of time. The 5-4-3 rule ensures this. Each repeater that a signal goes through adds a small amount of time to the process, so the rule is designed to minimize transmission times of the signals. Too much latency on the LAN increases the number of late collisions and makes the LAN less efficient.

The next page will discuss hubs.
5.1
Cabling LANs
5.1.7
Hubs



This page will describe the three types of hubs.

Hubs are actually multiport repeaters. The difference between hubs and repeaters is usually the number of ports that each device provides. A typical repeater usually has two ports. A hub generally has from 4 to 24 ports. Hubs are most commonly used in Ethernet 10BASE-T or 100BASE-T networks.

The use of a hub changes the network from a linear bus with each device plugged directly into the wire to a star topology. Data that arrives over the cables to a hub port is electrically repeated on all the other ports connected to the network segment.

Hubs come in three basic types:

* Passive – A passive hub serves as a physical connection point only. It does not manipulate or view the traffic that crosses it. It does not boost or clean the signal. A passive hub is used only to share the physical media. A passive hub does not need electrical power.
* Active – An active hub must be plugged into an electrical outlet because it needs power to amplify a signal before it is sent to the other ports.
* Intelligent – Intelligent hubs are sometimes called smart hubs. They function like active hubs with microprocessor chips and diagnostic capabilities. Intelligent hubs are more expensive than active hubs. They are also more useful in troubleshooting situations.

Devices attached to a hub receive all traffic that travels through the hub. If many devices are attached to the hub, collisions are more likely to occur. A collision occurs when two or more workstations send data over the network wire at the same time. All data is corrupted when this occurs. All devices that are connected to the same network segment are members of the same collision domain.

Sometimes hubs are called concentrators since they are central connection points for Ethernet LANs.

The Lab Activity will teach students about the price of different network components.

The next page discusses wireless networks.
5.1
Cabling LANs
5.1.8
Wireless



This page will explain how a wireless network can be created with much less cabling than other networks.

Wireless signals are electromagnetic waves that travel through the air. Wireless networks use radio frequency (RF), laser, infrared (IR), satellite, or microwaves to carry signals between computers without a permanent cable connection. The only permanent cabling can be to the access points for the network. Workstations within the range of the wireless network can be moved easily without the need to connect and reconnect network cables.

A common application of wireless data communication is for mobile use. Some examples of mobile use include commuters, airplanes, satellites, remote space probes, space shuttles, and space stations.

At the core of wireless communication are devices called transmitters and receivers. The transmitter converts source data to electromagnetic waves that are sent to the receiver. The receiver then converts these electromagnetic waves back into data for the destination. For two-way communication, each device requires a transmitter and a receiver. Many networking device manufacturers build the transmitter and receiver into a single unit called a transceiver or wireless network card. All devices in a WLAN must have the correct wireless network card installed.

The two most common wireless technologies used for networking are IR and RF. IR technology has its weaknesses. Workstations and digital devices must be in the line of sight of the transmitter to work correctly. An infrared-based network can be used when all the digital devices that require network connectivity are in one room. IR networking technology can be installed quickly. However, the data signals can be weakened or obstructed by people who walk across the room or by moisture in the air. New IR technologies will be able to work out of sight.

RF technology allows devices to be in different rooms or buildings. The limited range of radio signals restricts the use of this kind of network. RF technology can be on single or multiple frequencies. A single radio frequency is subject to outside interference and geographic obstructions. It is also easily monitored by others, which makes the transmissions of data insecure. Spread spectrum uses multiple frequencies to increase the immunity to noise and to make it difficult for outsiders to intercept data transmissions.

Two approaches that are used to implement spread spectrum for WLAN transmissions are Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). The technical details of how these technologies work are beyond the scope of this course.

A large LAN can be broken into smaller segments. The next page will explain how bridges are used to accomplish this.
5.1
Cabling LANs
5.1.9
Bridges



This page will explain the function of bridges in a LAN.

There are times when it is necessary to break up a large LAN into smaller and more easily managed segments. This decreases the amount of traffic on a single LAN and can extend the geographical area past what a single LAN can support. The devices that are used to connect network segments together include bridges, switches, routers, and gateways. Switches and bridges operate at the data link layer of the OSI model. The function of the bridge is to make intelligent decisions about whether or not to pass signals on to the next segment of a network.

When a bridge receives a frame on the network, the destination MAC address is looked up in the bridge table to determine whether to filter, flood, or copy the frame onto another segment. This decision process occurs as follows:

* If the destination device is on the same segment as the frame, the bridge will not send the frame onto other segments. This process is known as filtering.
* If the destination device is on a different segment, the bridge forwards the frame to the appropriate segment.
* If the destination address is unknown to the bridge, the bridge forwards the frame to all segments except the one on which it was received. This process is known as flooding.

If placed strategically, a bridge can greatly improve network performance.

The next page will describe switches.
5.1
Cabling LANs
5.1.10
Swtiches



This page will explain the function of switches.

A switch is sometimes described as a multiport bridge. A typical bridge may have only two ports that link two network segments. A switch can have multiple ports based on the number of network segments that need to be linked. Like bridges, switches learn information about the data frames that are received from computers on the network. Switches use this information to build tables to determine the destination of data that is sent between computers on the network.

Although there are some similarities between the two, a switch is a more sophisticated device than a bridge. A bridge determines whether the frame should be forwarded to the other network segment based on the destination MAC address. A switch has many ports with many network segments connected to them. A switch chooses the port to which the destination device or workstation is connected. Ethernet switches are popular connectivity solutions because they improve network speed, bandwidth, and performance.

Switching is a technology that alleviates congestion in Ethernet LANs. Switches reduce traffic and increase bandwidth. Switches can easily replace hubs because switches work with the cable infrastructures that are already in place. This improves performance with minimal changes to a network.

All switching equipment perform two basic operations. The first operation is called switching data frames. This is the process by which a frame is received on an input medium and then transmitted to an output medium. The second is the maintenance of switching operations where switches build and maintain switching tables and search for loops.

Switches operate at much higher speeds than bridges and can support new functionality, such as virtual LANs.

An Ethernet switch has many benefits. One benefit is that it allows many users to communicate at the same time through the use of virtual circuits and dedicated network segments in a virtually collision-free environment. This maximizes the bandwidth available on the shared medium. Another benefit is that a switched LAN environment is very cost effective since the hardware and cables in place can be reused.

The Lab activity will help students understand the price of a LAN switch.

The next page will discuss NICs.
5.1
Cabling LANs
5.1.11
Host connectivity



This page will explain how NICs provide network connectivity.

The function of a NIC is to connect a host device to the network medium. A NIC is a printed circuit board that fits into the expansion slot on the motherboard or peripheral device of a computer. The NIC is also referred to as a network adapter. On laptop or notebook computers a NIC is the size of a credit card.

NICs are considered Layer 2 devices because each NIC carries a unique code called a MAC address. This address is used to control data communication for the host on the network. More will be learned about the MAC address later. NICs control host access to the medium.

In some cases the type of connector on the NIC does not match the type of media that needs to be connected to it. A good example is a Cisco 2500 router. This router has an AUI connector. That AUI connector needs to connect to a UTP Category 5 Ethernet cable. A transceiver is used to do this. A transceiver converts one type of signal or connector to another. For example, a transceiver can connect a 15-pin AUI interface to an RJ-45 jack. It is considered a Layer 1 device because it only works with bits and not with any address information or higher-level protocols.

NICs have no standardized symbol. It is implied that, when networking devices are attached to network media, there is a NIC or NIC-like device present. A dot on a topology map represents either a NIC interface or port, which acts like a NIC.

The next page discusses peer-to-peer networks.
5.1
Cabling LANs
5.1.12
Peer-to-peer



This page covers peer-to-peer networks.

When LAN and WAN technologies are used, many computers are interconnected to provide services to their users. To accomplish this, networked computers take on different roles or functions in relation to each other. Some types of applications require computers to function as equal partners. Other types of applications distribute their work so that one computer functions to serve a number of others in an unequal relationship.

Two computers generally use request and response protocols to communicate with each other. One computer issues a request for a service, and a second computer receives and responds to that request. The requestor acts like a client and the responder acts like a server.

In a peer-to-peer network, networked computers act as equal partners, or peers. As peers, each computer can take on the client function or the server function. Computer A may request for a file from Computer B, which then sends the file to Computer A. Computer A acts like the client and Computer B acts like the server. At a later time, Computers A and B can reverse roles.

In a peer-to-peer network, individual users control their own resources. The users may decide to share certain files with other users. The users may also require passwords before they allow others to access their resources. Since individual users make these decisions, there is no central point of control or administration in the network. In addition, individual users must back up their own systems to be able to recover from data loss in case of failures. When a computer acts as a server, the user of that machine may experience reduced performance as the machine serves the requests made by other systems.

Peer-to-peer networks are relatively easy to install and operate. No additional equipment is necessary beyond a suitable operating system installed on each computer. Since users control their own resources, no dedicated administrators are needed.

As networks grow, peer-to-peer relationships become increasingly difficult to coordinate. A peer-to-peer network works well with ten or fewer computers. Since peer-to-peer networks do not scale well, their efficiency decreases rapidly as the number of computers on the network increases. Also, individual users control access to the resources on their computers, which means security may be difficult to maintain. The client/server model of networking can be used to overcome the limitations of the peer-to-peer network.

Students will create a simple peer-to-peer network in the Lab Activity.

The next page discusses a client/server network.
5.1
Cabling LANs
5.1.13
Client/server



This page will describe a client/server environment.

In a client/server arrangement, network services are located on a dedicated computer called a server. The server responds to the requests of clients. The server is a central computer that is continuously available to respond to requests from clients for file, print, application, and other services. Most network operating systems adopt the form of a client/server relationship. Typically, desktop computers function as clients and one or more computers with additional processing power, memory, and specialized software function as servers.

Servers are designed to handle requests from many clients simultaneously. Before a client can access the server resources, the client must be identified and be authorized to use the resource. Each client is assigned an account name and password that is verified by an authentication service. The authentication service guards access to the network. With the centralization of user accounts, security, and access control, server-based networks simplify the administration of large networks.

The concentration of network resources such as files, printers, and applications on servers also makes it easier to back-up and maintain the data. Resources can be located on specialized, dedicated servers for easier access. Most client/server systems also include ways to enhance the network with new services that extend the usefulness of the network.

The centralized functions in a client/server network has substantial advantages and some disadvantages. Although a centralized server enhances security, ease of access, and control, it introduces a single point of failure into the network. Without an operational server, the network cannot function at all. Servers require a trained, expert staff member to administer and maintain. Server systems also require additional hardware and specialized software that add to the cost.

Figures and summarize the advantages and disadvantages of peer-to-peer and client/server networks.

In the Lab Activities, students will build a hub-based network and a switch-based network.

This page concludes this lesson. The next lesson will discuss cabling WANs. The first page focuses on the WAN physical layer.
5.2
Cabling WANs
5.2.1
WAN physical layer



This page describes the WAN physical layer.

The physical layer implementations vary based on the distance of the equipment from each service, the speed, and the type of service. Serial connections are used to support WAN services such as dedicated leased lines that run PPP or Frame Relay. The speed of these connections ranges from 2400 bps to T1 service at 1.544 Mbps and E1 service at 2.048 Mbps.

ISDN offers dial-on-demand connections or dial backup services. An ISDN Basic Rate Interface (BRI) is composed of two 64 kbps bearer channels (B channels) for data, and one delta channel (D channel) at 16 kbps used for signaling and other link-management tasks. PPP is typically used to carry data over the B channels.

As the demand for residential broadband high-speed services has increased, DSL and cable modem connections have become more popular. Typical residential DSL service can achieve T1/E1 speeds over the telephone line. Cable services use the coaxial cable TV line. A coaxial cable line provides high-speed connectivity that matches or exceeds DSL. DSL and cable modem service will be covered in more detail in a later module.

Students can identify the WAN physical layer components in the Interactive Media Activity.

The next page will describe WAN serial connections.
5.2
Cabling WANs
5.2.2
WAN serial connections



This page will discuss WAN serial connections.

For long distance communication, WANs use serial transmission. This is a process by which bits of data are sent over a single channel. This process provides reliable long distance communication and the use of a specific electromagnetic or optical frequency range.

Frequencies are measured in terms of cycles per second and expressed in Hz. Signals transmitted over voice grade telephone lines use 4 kHz. The size of the frequency range is referred to as bandwidth. In networking, bandwidth is a measure of the bits per second that are transmitted.

For a Cisco router, physical connectivity at the customer site is provided by one of two types of serial connections. The first type is a 60-pin connector. The second is a more compact 'smart serial' connector. The provider connector will vary depending on the type of service equipment.

If the connection is made directly to a service provider, or a device that provides signal clocking such as a channel/data service unit (CSU/DSU), the router will be a data terminal equipment (DTE) and use a DTE serial cable. Typically this is the case. However, there are occasions where the local router is required to provide the clocking rate and therefore will use a data communications equipment (DCE) cable. In the curriculum router labs one of the connected routers will need to provide the clocking function. Therefore, the connection will consist of a DCE and a DTE cable.

The next page will discuss routers and serial connections.
5.2
Cabling WANs
5.2.3
Routers and serial connections



This page will describe how routers and serial connections are used in a WAN.

Routers are responsible for routing data packets from source to destination within the LAN, and for providing connectivity to the WAN. Within a LAN environment the router contains broadcasts, provides local address resolution services, such as ARP and RARP, and may segment the network using a subnetwork structure. In order to provide these services the router must be connected to the LAN and WAN.

In addition to determining the cable type, it is necessary to determine whether DTE or DCE connectors are required. The DTE is the endpoint of the user's device on the WAN link. The DCE is typically the point where responsibility for delivering data passes into the hands of the service provider.

When connecting directly to a service provider, or to a device such as a CSU/DSU that will perform signal clocking, the router is a DTE and needs a DTE serial cable. This is typically the case for routers. However, there are cases when the router will need to be the DCE. When performing a back-to-back router scenario in a test environment, one of the routers will be a DTE and the other will be a DCE.

When cabling routers for serial connectivity, the routers will either have fixed or modular ports. The type of port being used will affect the syntax used later to configure each interface.

Interfaces on routers with fixed serial ports are labeled for port type and port number.

Interfaces on routers with modular serial ports are labeled for port type, slot, and port number. The slot is the location of the module. To configure a port on a modular card, it is necessary to specify the interface using the syntax "port type slot number/port number". Use the label "serial 1/0", when the interface is serial, the slot number where the module is installed is slot 1, and the port that is being referenced is port 0.

The first Lab Activity will require students to identify the Ethernet or Fast Ethernet interfaces on a router.

In the next two Lab Activities, students will create and troubleshoot a basic WAN.

The next page discusses routers and ISDN BRI connections.
5.2
Cabling WANs
5.2.4
Routers and ISDN BRI connections



This page will help students understand ISDN BRI connections.

With ISDN BRI, two types of interfaces may be used, BRI S/T and BRI U. Determine who is providing the Network Termination 1 (NT1) device in order to determine which interface type is needed.

An NT1 is an intermediate device located between the router and the service provider ISDN switch. The NT1 is used to connect four-wire subscriber wiring to the conventional two-wire local loop. In North America, the customer typically provides the NT1, while in the rest of the world the service provider provides the NT1 device.

It may be necessary to provide an external NT1 if the device is not already integrated into the router. Reviewing the labeling on the router interfaces is usually the easiest way to determine if the router has an integrated NT1. A BRI interface with an integrated NT1 is labeled BRI U. A BRI interface without an integrated NT1 is labeled BRI S/T. Because routers can have multiple ISDN interface types, determine which interface is needed when the router is purchased. The type of BRI interface may be determined by looking at the port label. To interconnect the ISDN BRI port to the service-provider device, use a UTP Category 5 straight-through cable.
CAUTION:

It is important to insert the cable running from an ISDN BRI port only to an ISDN jack or an ISDN switch. ISDN BRI uses voltages that can seriously damage non-ISDN devices.

The next page discusses DSL for a router.
5.2
Cabling WANs
5.2.5
Routers and DSL connections



This page describes routers and DSL connections.

The Cisco 827 ADSL router has one asymmetric digital subscriber line (ADSL) interface. To connect an ADSL line to the ADSL port on a router, do the following:

* Connect the phone cable to the ADSL port on the router.
* Connect the other end of the phone cable to the phone jack.

To connect a router for DSL service, use a phone cable with RJ-11 connectors. DSL works over standard telephone lines using pins 3 and 4 on a standard RJ-11 connector.

The next page will discuss cable connections.
5.2
Cabling WANs
5.2.6
Routers and cable connections



This page will explain how routers are connected to cable systems.

The Cisco uBR905 cable access router provides high-speed network access on the cable television system to residential and small office, home office (SOHO) subscribers. The uBR905 router has a coaxial cable, or F-connector, interface that connects directly to the cable system. Coaxial cable and an F connector are used to connect the router and cable system.

Use the following steps to connect the Cisco uBR905 cable access router to the cable system:

* Verify that the router is not connected to power.
* Locate the RF coaxial cable coming from the coaxial cable (TV) wall outlet.
* Install a cable splitter/directional coupler, if needed, to separate signals for TV and computer use. If necessary, also install a high-pass filter to prevent interference between the TV and computer signals.
* Connect the coaxial cable to the F connector of the router. Hand-tighten the connector, making sure that it is finger-tight, and then give it a 1/6 turn with a wrench.
* Make sure that all other coaxial cable connectors, all intermediate splitters, couplers, or ground blocks, are securely tightened from the distribution tap to the Cisco uBR905 router.

CAUTION:

Do not over tighten the connector. Over tightening may break off the connector. Do not use a torque wrench because of the danger of tightening the connector more than the recommended 1/6 turns after it is finger-tight.

The next page will discuss console connections.
5.2
Cabling WANs
5.2.7
Setting up console connections



This page will explain how console connections are set up.

To initially configure the Cisco device, a management connection must be directly connected to the device. For Cisco equipment this management attachment is called a console port. The console port allows monitoring and configuration of a Cisco hub, switch, or router.

The cable used between a terminal and a console port is a rollover cable, with RJ-45 connectors. The rollover cable, also known as a console cable, has a different pinout than the straight-through or crossover RJ-45 cables used with Ethernet or the ISDN BRI. The pinout for a rollover is as follows:

1 to 8

2 to 7

3 to 6

4 to 5

5 to 4

6 to 3

7 to 2

8 to 1

To set up a connection between the terminal and the Cisco console port, perform two steps. First, connect the devices using a rollover cable from the router console port to the workstation serial port. An RJ-45-to-DB-9 or an RJ-45-to-DB-25 adapter may be required for the PC or terminal. Next, configure the terminal emulation application with the following common equipment (COM) port settings: 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control.

The AUX port is used to provide out-of-band management through a modem. The AUX port must be configured by way of the console port before it can be used. The AUX port also uses the settings of 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control.

In the Lab Activity, students will establish a console connection to a router or switch.

The Interactive Media Activity provides a detailed view of a console cable.

This page concludes this lesson. The next page will summarize the main points from the module.
Summary



This page summarizes the topics discussed in this module.

Ethernet is the most widely used LAN technology and can be implemented on a variety of media. Ethernet technologies provide a variety of network speeds, from 10 Mbps to Gigabit Ethernet, which can be applied to appropriate areas of a network. Media and connector requirements differ for various Ethernet implementations.

The connector on a network interface card (NIC) must match the media. A bayonet nut connector (BNC) connector is required to connect to coaxial cable. A fiber connector is required to connect to fiber media. The registered jack (RJ-45) connector used with twisted-pair wire is the most common type of connector used in LAN implementations. Ethernet

When twisted-pair wire is used to connect devices, the appropriate wire sequence, or pinout, must be determined as well. A crossover cable is used to connect two similar devices, such as two PCs. A straight-through cable is used to connect different devices, such as connections between a switch and a PC. A rollover cable is used to connect a PC to the console port of a router.

Repeaters regenerate and retime network signals and allow them to travel a longer distance on the media. Hubs are multi-port repeaters. Data arriving at a hub port is electrically repeated on all the other ports connected to the same network segment, except for the port on which the data arrived. Sometimes hubs are called concentrators, because hubs often serve as a central connection point for an Ethernet LAN.

A wireless network can be created with much less cabling than other networks. The only permanent cabling might be to the access points for the network. At the core of wireless communication are devices called transmitters and receivers. The transmitter converts source data to electromagnetic (EM) waves that are passed to the receiver. The receiver then converts these electromagnetic waves back into data for the destination. The two most common wireless technologies used for networking are infrared (IR) and radio frequency (RF).

There are times when it is necessary to break up a large LAN into smaller, more easily managed segments. The devices that are used to define and connect network segments include bridges, switches, routers, and gateways.

A bridge uses the destination MAC address to determine whether to filter, flood, or copy the frame onto another segment. If placed strategically, a bridge can greatly improve network performance.

A switch is sometimes described as a multi-port bridge. Although there are some similarities between the two, a switch is a more sophisticated device than a bridge. Switches operate at much higher speeds than bridges and can support new functionality, such as virtual LANs.

Routers are responsible for routing data packets from source to destination within the LAN, and for providing connectivity to the WAN. Within a LAN environment the router controls broadcasts, provides local address resolution services, such as ARP and RARP, and may segment the network using a subnetwork structure.

Computers typically communicate with each other by using request/response protocols. One computer issues a request for a service, and a second computer receives and responds to that request. In a peer-to-peer network, networked computers act as equal partners, or peers. As peers, each computer can take on the client function or the server function. In a client/server arrangement, network services are located on a dedicated computer called a server. The server responds to the requests of clients.

WAN connection types include high-speed serial links, ISDN, DSL, and cable modems. Each of these requires a specific media and connector. To interconnect the ISDN BRI port to the service-provider device, a UTP Category 5 straight-through cable with RJ-45 connectors, is used. A phone cable and an RJ-11 connector are used to connect a router for DSL service. Coaxial cable and a BNC connector are used to connect a router for cable service.

In addition to the connection type, it is necessary to determine whether DTE or DCE connectors are required on internetworking devices. The DTE is the endpoint of the user's private network on the WAN link. The DCE is typically the point where responsibility for delivering data passes to the service provider. When connecting directly to a service provider, or to a device such as a CSU/DSU that will perform signal clocking, the router is a DTE and needs a DTE serial cable. This is typically the case for routers. However, there are cases when the router will need to be the DCE.



ccna module 5 text