4.1-4.4 Ethernet

You have been tasked with designing a high-speed Ethernet network. Your client's building already has 150-ohm shielded twisted pair (STP) wiring installed. Due to budget constraints, they have asked you to reuse the existing wiring instead of installing new fiber optic cabling. Which Ethernet standard could you implement in this situation?

1000BaseCX The 1000BaseCX standard specifies 150-ohm STP cabling. The maximum cable length is 25 meters. The 10BaseFL, 1000BaseSX, 1000BaseLX, and 1000BaseZX standards employ fiber optic cabling. 1000BaseT uses Category 5 UTP instead of STP cabling.

Mesh

A break in a single link in a mesh topology has no effect on communications. Data can be routed to the destination device by taking a different (though sometimes longer) path through the mesh topology.

Star

A break in a star means that the device connected to the central device through that cable can no longer communicate on the network. All other hosts will be able to communicate with all other devices.

Keepalive Signal

A message sent by one device (such as a network interface card) to another device (such as a switch) to check that the link between the two is operating. A keepalive Signal is sometimes referred to as a heartbeat.

You manage the two-location network shown in the exhibit. Workstations and servers at each location connect to a patch panel using behind-the-wall wiring. The patch panel then connects network hosts to one of three 1000BASE-T switches. Routers are implemented at each location to connect the two networks together using a private WAN. The switch ports have auto-MDIX disabled. Drag the cable type on the left to the most appropriate network location on the right. Each cable type can be used more than once.

A. Drop cables Cat 6 straight-through UTP B. Patch cables Cat 6 straight-through UTP C. Uplink cables Cat 6 crossover UTP D. WAN cables Single-mode fiber optic In this scenario, the following cables should be used in the following locations: Drop cables = Cat 6 straight-through UTP. Patch cables = Cat 6 straight-through UTP. Uplink cables = Cat 6 crossover UTP (Cat 6 straight-through UTP can be used instead if auto-MDIX is enabled on the switch ports). WAN cable = Single-mode fiber optic. Because 1000BASE-T Ethernet switches are in use at both locations, Cat 5 or better UTP must be used. Because the distance between locations is greater than 550 meters, single-mode fiber optic cable must be used. This will require the use of 1000BASE-LX or 1000BASE-EX transceivers on both routers.

4.2 Ethernet Specifications

As you study this section, answer the following questions: > What is the maximum cable length for most Ethernet standards that use twisted pair cables? > Which twisted pair cable category should you use on a 1000BaseT network? > What is the advantage of using single mode cable on a 1000BaseLX network? > What is the difference between 1000BaseLX and 1000BaseSX? In this section, you will learn to: > Reconnect to an Ethernet network

4.1.3 Practice Questions

CIST 1401

4.2.4 Practice Questions

CIST 1401

4.3.4 Practice Questions

CIST 1401

4.4.10 Practice Questions

CIST 1401

You have a network connected using a full physical mesh topology. The link between device A and device B is broken. Which of the following best describes what affect this will have on network communications?

Device A will be able to communicate with all other devices. With a mesh topology, a break in a single link has no effect on communications. Data can be routed to the destination device by taking a different (sometimes longer) path through the mesh topology.

Networking Devices

Devices used on Ethernet networks include: > NICs > Hubs (obsolete) > Switches > Routers

Physical Addresses

Ethernet devices are identified by MAC address, which is burned into the network interface card.

4.1.2 Ethernet Facts

Ethernet is the most popular networking architecture for LANs. It offers high performance at a low cost and is easy to install and manage. The following table describes various details about Ethernet:

4.2.2 Ethernet Specifications Facts

Ethernet standards are defined by the IEEE 802.3 committee. The following table compares the characteristics of various Ethernet implementations:

Transmission Media

Ethernet supports the following cable types: > Unshielded twisted pair (UTP) cables with RJ45 connectors. This is the most common transmission medium used for Ethernet. > Fiber optic cables, which are most commonly used for high-speed applications such as server connections or media streaming. > Coaxial cables for older Ethernet implementations (often called thinnet or thicknet networks).

Topology

Ethernet uses the following networking topologies as specified: > Physical bus, logical bus > Physical star, logical bus > Physical star, logical star

Ethernet 100BaseFX networks use what type of cabling?

Fiber optic Ethernet 100BaseFX networks use fiber optic cabling.

Light Link - Solid Green Activity - Flashing Collision - Flashing/Lit Constantly

If the collision light is constantly flashing, then there are too many collisions on the network. Possible causes include the following: > Too many devices on the segment. As the number of devices increases, so does the number of collisions. Reducing the number of devices or using switches, bridges, or routers to divide the network into multiple collision domains reduces or even eliminates the number of collisions. > Faulty cabling or cable runs that are too long. > A faulty NIC that does not properly sense the medium before transmitting.

Light Link- Red/Amber Activity - Unlit Collision - Unlit

If the link light comes on and is not green, then the NIC has detected a signal, but the signal is not what was expected. Possible cause includes: > Faulty transceiver on the NIC or remote device. > Incorrectly configured network cabling > Incompatible network standards *On some switches, an amber link light indicates a slower connection (such as a 100Mpbs connection instead of a 1000Mbps connection, which might show a green light).

Collision

In a half duplex Ethernet network, a collision is the result of two devices on the same Ethernet network attempting to transmit data at exactly the same time.

4.4.5 Explore Physical Connectivity

In this lab, you explore different methods of troubleshooting network communication problems using the ping command, the link and network activity lights on network cards and switches, and the Windows Control Panel app named Network and Sharing Center. Use Exhibits to see the network diagram and wiring schematics of the network. The following IP addresses are used in this lab: *See Table Complete this lab as follows: Move the network cable to the good NIC on Exec - Cable connected to good NIC on the motherboard - Exec connected to the network Replace faulty cable to Office1 in the Network Closet - Faulty cable removed - Computer is connected to the network Plug Switch into Critical Load Bank outlet 1. Under Networking Closet, select Hardware. 2. Zoom in on the switch in the rack to view the power and network activity lights.What do the power lights indicate? What do these lights tell you about the status of the network (specifically ports 1, 3, and 5)? 3. On the ITAdmin workstation, ping each of the following computers using the IP addresses shown. 4. On ITAdmin, check the network connectivity using:The taskbar's Network iconThe Network and Sharing CenterThe Network Interface Card (NIC) link lights on the computer What information about the network can you gather from viewing and selecting the Network icon? What does the Network and Sharing Center tell you about the status of network communications? What can you determine from the link and network activity lights on this workstation? 5. On ITAdmin, disconnect the network cable and then check the network connectivity using: The Network Interface Card (NIC) link lights on the computer The ping status for: - Office1: 192.168.0.30 - CorpNet Router's internal interface: 198.28.56.1 The taskbar's Network icon The Network and Sharing Center What can you determine from the link and network activity lights on this workstation? What information about the network can you gather from the ping command and from viewing and selecting the Network icon? What does the Network and Sharing Center tell you about the status of network communications? 6. In the Networking Closet, examine the current link and activity lights for ITAdmin. What do these lights tell you about ITAdmin network connectivity? 7. On ITAdmin, plug the Ethernet cable back into the onboard Ethernet port. What do the link and activity lights tell you about ITAdmin network connectivity? 8. On Exec, check the network connectivity using: The taskbar's Network icon The Network and Sharing Center The Network Interface Card (NIC) link lights on the computer What information about the network can you gather from the Network icon and from selecting the Network icon? What does the Network and Sharing Center tell you about the status of network communications? What can you determine from the link and network activity lights on this workstation? 9. Since the Executive Office workstation has two NICs, check for a bad NIC by moving the networking cable the other NIC. What can you determine from the link and network activity lights on this workstation now? 10. On Exec, do the following: Ping the IP address of Office1. Ping the IP address of CorpServer. Ping 65.86.1.1 (the ISP). What do the results tell you about the status of network communications? 11. In the Networking Closet, is there any change to the status of the network activity lights on the switch for the ports listed in step 2? 12. On Office1, check the network connectivity by viewing the computer's NIC link and network activity lights. What can you determine from their current status? 13. Since trying a different Ethernet cable is easier than replacing a NIC, replace the existing cable with a known good cable from the Shelf. What happens to the link and network activity lights on the workstation? What can you determine from these results? 14. In the Networking Closet, test the network patch cable for Office1 by replacing the cable with a known good cable from the Shelf. What happens to the network activity lights on the switch? 15. On Office1, test the network connection by pinging the following devices: Office2: 192.168.0.31 ITAdmin: 192.168.0.33 Exec: 192.168.0.34 ISP: 65.86.1.1 What do the results indicate? 16. In the Networking Closet, disconnect the UPS power plug from the wall outlet. What is the status of the following: Power lights and the network activity lights for all devices in the Networking Closet CorpServer monitor CorpiSCSI monitor 17. On CorpServer, ping the following devices: Office1: 192.168.0.30 The CorpNet Router's internal interface: 198.28.56.1 View the network status using the Network and Sharing Center. What do the results tell you about the status of network communications? 18. In the Networking Closet, switch to the Back view of the rack and move the male AC Power Connector for the switch from the non-critical load bank section (on the left) to the critical load bank section (on the right).(To identify the correct male AC Power Connector, select the power cable connected to the back of the switch; the other end of the cable will be outlined.) 19. In the Networking Closet, switch to the Front view of the rack. What is the status of the power lights for all devices on the rack and the network activity lights on the switch (specifically ports 23 and 24)? 20. On CorpServer, ping the following: Office1: 192.168.0.30 The CorpNet Router's internal interface: 198.28.56.1 The ISP: 65.86.1.1 What do the results tell you about the status of network communications? 21. In the Networking Closet, reconnect the AC power cord from the UPS to the wall outlet. What changes did this make to your systems?

Crossover

Matches the transmit (Tx) wires on one connector with the receive (Rx) wires on the other connector. A crossover cable is used when crossing is not performed automatically or when crossover is performed twice. Use a crossover cable when connecting the following devices: > Workstation to a workstation, router to a router, or workstation to a router (in a back-to-back configuration) > Uplink port on a hub or switch to an uplink port on a hub or a switch. > Workstation or router to the uplink port on a hub or a switch. > Hub or a switch using a regular port to a hub or a switch using a regular port.

What topology is used with 100BaseTX Fast Ethernet networks? (Select two.)

Physical star/logical bus Physical star/logical star 100BaseTX Fast Ethernet networks use a physical star/logical bus topology when a hub is used or a physical star/logical star when a switch is used.

You've connected a cable certifier to an RJ45 wall jack and the output shown below is displayed on the device. What does this output indicate? (Select two.)

Pin 6 is open. Pin 4 is open. In this example, any connections displayed with no characters between the pin numbers are open connections. This problem is usually caused by: Poor connections between the wire and the RJ45 jack. Individual wires broken within the UTP cable. Output with x characters between pins indicates that they are shorted. Correctly functioning connections are displayed using - characters in the output of the cable certifier. Cross-over connections are displayed with lines between the crossed-over pins.

You are creating an Ethernet network for your company. The shipping department is located in a different building that is located 150 meters from the main wiring closet. You connect a single Cat 6a cable to connect the wiring closet to the shipping building. Which of the following should you include in your plan?

Repeater A repeater regenerates the signal and removes the unwanted effects caused by attenuation. Attenuation is the loss of signal strength from one end of a cable to the other. In this example, the distance from the wiring closet to the other building exceeds the 100-meter maximum for Ethernet, so a repeater is necessary to regenerate the signal. Use shielded twisted pair to protect against electromagnetic interference (EMI). Shielded cables have a metal foil that encloses all of the wires. Some cables might also include a drain wire, which is a bare wire in the middle of the wire bundle that helps to reduce EMI. More expensive cable might also use a metal foil around each pair of wires. The spanning tree protocol runs on switches to prevent switching loops by making only a single path between switches active at a single time. When using half-duplex communications, devices perform collision detection because the transmission medium is shared.

A user from the sales department calls to report that he is experiencing problems connecting to the sales file server. All users in the sales department connect to the sales server through a single Ethernet switch. No other users have reported problems connecting to the sales server. Which of the following troubleshooting actions are you most likely to perform first?

Replace the network card in the user's computer. In this scenario, you are most likely to replace the network card in the user's computer. As there is only one user experiencing a problem, you are unlikely to replace the network card in the server or replace the Ethernet switch. For the same reason, you are also unlikely to replace the network card drivers on the server. If more than one user were experiencing the problem, any of the options could be a valid troubleshooting step.

You have purchased a new router that you need to configure. You need to connect a workstation to the router's console port to complete the configuration tasks. Which type of cable would you most likely use?

Rollover Use a rollover cable to connect a workstation to the console port of a router or a switch. The rollover cable has an RJ45 connector on one end to connect to the console port. The other end has a serial connector to connect to the serial port of the workstation. You then run a terminal emulation program on the workstation to connect to the console of the router or switch to perform configuration and management tasks. Use a straight-through or crossover Ethernet cable to connect devices using the Ethernet RJ45 ports. An RG6 cable is a coaxial cable.

You want to implement an Ethernet network at very long distances using fiber optic cables. Which standard and cable type would you choose? (Select two.)

Single-mode fiber 1000BaseLX Of the standards listed in this question, 1000BaseLX provides the greatest cable length (think of the "L" in 1000BaseLX as "long"). When using fiber optic across long distances, use single-mode fiber. Multi-mode fiber is cheaper, but has a shorter maximum distance than single-mode fiber. 1000BaseSX is for short fiber optic, and 1000BaseCX uses short copper within a wiring closet.

Fast Ethernet

Standard - 100BaseTX Bandwidth - 100 Mbps (half-duplex) | 200 Mbps (full-duplex) Cable Type - Twisted pair (Cat5 or higher), uses 2 pairs of wires Maximum Segment Length - 100 meters

You need to connect a workstation to a switch using a regular port on the switch (not an uplink port). The switch does not support auto-MDI. Which type of cable should you use?

Straight-through Use a straight-through cable to connect a workstation or router to a regular switch port. Use a crossover cable to connect the workstation to the uplink port. Use a rollover cable to connect the workstation to the console port of the switch. Use a loopback plug to allow a workstation to communicate with itself through its own network adapter.

Angela is the network administrator for a rapidly growing company with a 100BaseT network. Users have recently complained about slow file transfers. While checking network traffic, Angela discovers a high number of collisions. Which connectivity device would best reduce the number of collisions and allow future growth?

Switch A switch would be the best choice in this situation. A bridge will segment traffic and reduce collisions, but it would be harder to maintain and harder to add new bridges as the network grows. A router would allow growth and reduce collisions. Switches can provide those benefits at a lower cost per port and offer more administration options.

Cable Types

The following table describes which cable type you should use in various connection scenarios:

Light Link - Solid Green Activity - Flashing Collision - Unlit

This is a normal condition that indicates a valid active connection. The Activity light flashes periodically even if you are not currently sending data over the link (this is known as a heartbeat or keepalive signal that lets the NIC know it has an active connection).

Light Link - Solid Green Activity - Flashing Collision - Flashing/Lit Occasionally

This is a normal condition that indicates collisions. A small number of collisions are to be expected on an Ethernet network that uses a hub. *If your network uses full-duplex switches, there should be no collisions on the network.

UTP

UTP stands for unshielded twisted pair. UTP cables are easy to work with and less expensive than shielded cables.

4.4.2 Physical Network Topology Troubleshooting Facts

When troubleshooting physical problems, it helps to identify the fault domain. The fault domain is the location of a physical problem. It's often manifested when you identify the boundary between communicating devices. For example, if a cable break occurs, a given host might be able to communicate with some devices, but not others. When you identify the fault domain, you identify the boundaries of communication and the most probable location of the physical problem. The following table compares how a single break in the network affects device-to-device communication for specific topologies:

A rollover cable might also have an RJ45 connector on both ends, requiring an adapter to convert from the RJ45 connector to the serial cable.

When you connect Ethernet devices, it's important that the transmit (Tx) wires from one device are matched with the receive (Rx) wires on the other device. To help understand how to connect devices together, be aware of the following: > Network interface cards in workstations and routers send data on the transmit pins and expect to receive data on the receive pins. > Crossing is automatically performed within a hub or the switch between ports used for connecting devices to the hub or a switch. > Uplink ports on hubs and switches are not crossed.

4.4.4 Link Status Troubleshooting Facts

*Because collisions are associated with hub-based Ethernet networks, modern switches do not typically include a collision light. If a single device is unable to communicate on the network, begin troubleshooting by verifying the physical network connection. Most network cards include link and status lights that can help you verify physical connectivity. The following troubleshooting table describes various light combinations and their meanings:

Your network follows the 100BaseTX specifications for Fast Ethernet. What is the maximum cable segment length allowed?

100 meters Fast Ethernet using twisted pair cables (either 100BaseT4 or 100BaseTX) has a maximum cable segment length of 100 meters. All Ethernet networks that use twisted pair cable (Ethernet, Fast Ethernet, Gigabit Ethernet) have a distance limitation of 100 meters.

Which Gigabit Ethernet standard can support long network segments up to a maximum of 5 km when used with single-mode fiber optic cable?

1000BaseLX 1000BaseLX supports segment lengths of up to 5 km when used with single-mode fiber optic cable. This maximum segment length is cut to 550 m when multimode fiber optic cable is used. 1000BaseSX supports segment lengths of only 550 meters. 1000BaseCX uses copper wire and supports segment lengths of only 25 meters. 1000BaseT uses twisted pair cables.

You have been tasked with designing an Ethernet network. Your client needs to implement a very high-speed network backbone between campus buildings, some of which are around 300 meters apart. Multi-mode fiber optic cabling has already been installed between buildings. Your client has asked that you use the existing cabling. Which Ethernet standard meets these guidelines? (Choose two.)

1000BaseSX 10GBaseSR 10GBaseSR and 1000BaseSX can operate within these parameters. Both will support segment lengths 300 meters long and can use multi-mode fiber optic cabling. 10BaseFL isn't a good choice because its data transmission rate is relatively slow. 1000BaseCX and 1000BaseT both use copper wiring.

Which Gigabit Ethernet standard uses multimode fiber optic cabling and supports network segments up to a maximum of 550 meters long?

1000BaseSX The 1000BaseSX standard uses multimode fiber optic cable with a maximum segment length of 550 meters. However, to implement segments this long, you must use 50-micron 500MHz/km multimode fiber optic cable. Other types of cable will shorten the maximum segment length. 1000BaseFX also supports lengths up to 550 meters using multimode cable. 1000BaseFX supports distances up to 10 kilometers using single mode cable. 1000BaseZX has a maximum segment length of up to 100 km. 1000BaseCX and 1000BaseT use copper cabling instead of fiber optic.

Which of the following use the CSMA/CD access method?

1000BaseT CSMA/CD stands for carrier sense multiple access/collision detection. It defines the steps network devices take when two devices attempt to use a data channel simultaneously. Ethernet networks use CSMA/CD, including 1000BaseT.

Which of the following Ethernet standards uses fiber-optic cabling? (Select two.)

100BaseFX 1000BaseLX 100BaseFX and 1000BaseLX are Ethernet standards that use fiber optic cabling. Following the Ethernet naming conventions: > F designates fiber-optic cables. Ethernet standards with the F designation are 10BaseFL and 100BaseFX. > L designates long distances and requires fiber-optic to support the distance. Ethernet standards with the L designation are 10BaseFL, 1000BaseLX, and 10GBaseLR. > S designates short distances that use fiber-optic cables. Ethernet standards with the S designation are 1000BaseSX and 10GBaseSR. > T designates twisted pair cables. Ethernet standards with the T designation are 10BaseT, 100BaseTX, 100BaseT4, and 1000BaseT. > C designates copper cables. The 1000BaseCX standard is for fast Ethernet at short distances within wiring closets.

You are planning a network for an educational campus. Due to the size of the buildings and the distance between them, you have elected to use 10BaseFL hubs, cabling, and network interface cards. What is the maximum length for the network cable between a workstation and a hub?

2000 meters The maximum length for a 10BaseFL network segment is 2000 meters (2 km). Because a 10BaseFL network uses a physical star topology, a segment is defined as one of the arms of the star (between the hub and a host). That means the fiber optic cable between the hub and a workstation can be up to 2000 meters long. 1000BaseSX and 1000BaseLX support multimode cable up to 550 meters. 100 meters is the maximum twisted pair cable length.

Your network follows the 100BaseFX specifications for Fast Ethernet and uses half-duplex multi-mode cable. What is the maximum cable segment length allowed?

412 meters 100BaseFX half-duplex multimode cable has a maximum segment length of 412 meters. 1000BaseSX and 1000BaseLX support multimode cable up to 550 meters. 10BaseFL supports fiber optic cable between 1,000 and 2,000 meters.

Full-Duplex

> Collision detection is turned off. The device can send and receive at the same time. > Mode requires full-duplex capable NICs. > Mode requires switches with a dedicated switch ports (a single device per port). > Bandwidth - Doube the rated bandwidth (200 Mbps for 100BaseT and so on.)

Half-Duplex

> Collision detection is turned on. > The devices can send or receive in only only direction at a time. > Devices connected to a hub must use half-duplex communication. > Up to the rated bandwidth (100 Mbps for 100BaseT and so on.)

You should also know the following facts about Ethernet:

> The maximum cable length for UTP Ethernet T implementations is 100 meters for all standards. > Ethernet standards support a maximum of 1024 hosts on a single subnet. *Cat5e supersedes the Cat5 specification. The original Cat5 cable specification published by the IEEE 802.3 committee supported gigabit Ethernet, but Cat5 did not reliably perform at gigabit speed in the real world. Cat5e was developed to reliably support gigabit Ethernet.

Use the exhibit to match the connector type on the left with the corresponding letter on the right.

A DB25 B DB9 C RJ45 D RJ11 E LC F BNC G F-Type A DB25 connectors are older serial connectors. B DB9 connectors are usually on the ends of RS232 serial cables. C RJ45 connectors are used for Ethernet networking with twisted pair cables. D RJ11 connectors are used for dial-up and some DSL internet connections. E LC connectors are used with fiber optic cables. F BNC connectors are used with coaxial cables on 10Base2 Ethernet networks. G F-Type connectors are used with coaxial cables that create cable TV and broadband cable connections.

MAC Address

A Media Access Control (MAC) address is a unique identifier burned into the ROM of every Ethernet NIC.

Bus

A break in the network bus means that the end of the network bus is no longer terminated. For this reason, a break in the bus typically means that no devices can communicate. Consider the following examples: > When a cable on the network breaks, each end of the cable on either side of the break loses its termination. > When a cable becomes loose or is disconnected, the computer is not connected to the network; this also creates an end that is not terminated. Likewise, when a terminator becomes loose, there is an end that is not terminated. *It is difficult to identify the location of a break on a true bus network.

Ring

A break in the ring means that messages can only travel in one direction (downstream) to the break. Computers can send messages downstream to other other devices, but cannot receive any responses because of the break.

Crossover Cable

A crossover cable matches the transmit (Tx) wires on one connector with the receive (Rx) wires on the other connector. A crossover cable is used when crossing is not performed automatically or when crossover is performed twice.

Frames

A frame is a unit of data that is ready to be sent on the network medium. Ethernet frames contain the following components: > The preamble is a set of alternating ones and zeros terminated by two ones (11) that mark it as a frame. > The destination address identifies the receiving host's MAC address. > The source address identifies the sending host's MAC address. > The data is the information that needs to be transmitted from one host to the other. > Optional bits pad the frame. Ethernet frames are between 64 and 1518 bytes in size. If the frame is smaller than 64 bytes , the sending NIC places junk data in the pad to make it the required minimum of 64 bytes. > Cyclic Redundancy Check (CRC) is the result of a mathematical calculation performed on the frame. The CRC helps verify that the frame contents have arrived uncorrupted.

Rollover

A rollover cable is a cable with an RJ45 connector on one end and an RS232 (serial) connector on the other end. Use a rollover cable to connect the serial port on a workstation to the console connector on a router or switch, and then run a terminal emulation program on the workstation to connect to the console of the router or switch to perform configuration and management tasks. A rollover cable might also have an RJ45 connector on both ends, requiring an adapter to convert from the RJ45 connector to the serial cable. When terminated with an RJ45 connector on both ends, the wires within the connectors are rolled over to the opposite connector as follows: > Pin 1 is connected to pin 8 > Pin 2 is connected to pin 7 > Pin 3 is connected to pin 6 > Pin 4 is connected to pin 5

Rollover

A rollover cable might also have an RJ45 connector on both ends, requiring an adapter to convert from the RJ45 connector to the serial cable.

Light Link - Solid Green Activity - Unlit Collision - Unlit

A solid green link light indicates a valid network connection. However, an Activity light that never lights up means that no data is being received. To resolve this issue, check all components and connections.

Straight-Through

A straight-through cable connects each wire to the same pin on each connector (pin 1 to pin 1, pin 2 to pin 2 etc.). A straight-through cable is used when the crossover is performed with a hub or a switch. Use a straight-through cable when connecting the following devices: > Workstation to a regular port on a hub or switch. > Router to a regular port on a hub or a switch. > Regular port on a hub or a switch to an uplink port on a hub or a switch.

Straight-Through Cable

A straight-through cable connects each wire to the same pin on each connector (pin 1 to pin 1, pin 2 to pin 2, etc.). A straight-through cable is used when a crossover is performed with a hub or a switch.

You have a network connected using a physical star topology. One of the drop cables connecting a workstation has been removed. Which of the following best describes what affect this will have on network communications?

All devices will be able to communicate, except the device connected with the drop cable . A break in a cable in a star means that the device connected to the central device (hub or switch) through that cable can no longer communicate on the network. All other hosts will be able to communicate with all other devices.

During a network infrastructure upgrade, you have replaced two 10 Mbps hubs with switches and upgraded from Category 3 UTP cable to Category 5e. During the process, you accidentally cut the Cat 5e patch cable that stretches from the network printer to the upgraded switch. What is the impact on the network?

All network nodes except the printer will be available. UTP cable and switches are associated with a star network topology. In a star topology, each device is attached to the network using its own patch cable. If the cable were to fail for any reason, only the device connected by that cable would be unavailable.

Light Link - Solid Green Activity - Flashing Constantly Collision - Flashing/Lit Occasionally

An Activity light that is continuously flashing indicates that there is constant traffic being sent or received on the link. This could be caused by a device that is very busy (such as a server). In most cases, there should be at least some periods of little or no activity. A constantly flashing activity light could be caused by a faulty NIC on the link that is constantly sending out data. This condition is known as chattering or jabbering.

You are implementing a SOHO network for a local business. The ISP has already installed and connected a cable modem in the business. The business has four computers that need to communicate with each other and the internet. The ISP's cable modem has only one RJ45 port. You need to set up the network within the following parameters: > You must spend as little money as possible. > You must not purchase unnecessary equipment. > Computers need to have a gigabit connection to the network. > New devices should not require management or configuration. You examine each computer and notice only one of the four computers has a wireless NIC; they all have Ethernet NICs. What should you purchase?

An unmanaged switch and CAT 5e cabling. You should purchase an unmanaged switch and CAT 5e cabling. Switches offer guaranteed bandwidth to each switch port and full-duplex communication. Unmanaged switches are autonomous in their function, requiring no port management or configuration. CAT 5e cabling supports transfer speeds up to 1000 Mbps. Purchasing a new cable modem with a built-in switch would be more expensive than an unmanaged switch. Additionally, CAT6a cabling is unnecessary for this type of network. Because all of the computers already have wired NICs, purchasing a wireless AP and three new wireless NICs would introduce new costs. The wireless AP would also require additional management and configuration. Hubs suffer from collisions, so only half-duplex communication is possible. This wouldn't support 1000 Mbps speeds. A small business with four computers doesn't need the additional features that a managed switch provides.

Cable Facts

As a general rule, use a crossover cable when connecting two like devices, and use a straight-through cable when connecting different devices or port types. > If crossover is not performed by either device, use a crossover cable to connect the devices. > If crossover is performed by both devices, use a crossover cable to perform the crossing three times. > If crossover is performed by one device, use a straight-through cable. For most installations, a straight-through cable is used from the hub or switch in the wiring closet to the wall plate in an office, and another straight-through cable is used between the wall plate and the workstation. Crossing is performed at the hub or the switch, not at any of the cables connecting the workstation to the hub or switch. > To tell the difference between a crossover and a straight-through cable, place the connectors side by side facing the same direction. - If the wires are in the same order on both connectors, the cable is a straight-through cable. - If the wires are in a different order, the cable is a crossover cable. *Pre-made crossover cables often have a special jacket color (such as red). However, you cannot rely on the cable color only to tell the difference between a crossover and a straight-through cable. On some hubs and switches, the uplink port has a button or switch that lets you use it as a regular port (with crossing) or an uplink port (without crossing). On others, the uplink port is shared with one regular port. You can use either port, but not at the same time. > Some hubs and switches include the letter X in the port labeling to identify ports that perform crossing. > Most modern switches use Auto-MDI/MDIX, which senses the cable type used and performs crossing based on the cable. For these devices, you do not need to be concerned with which cable you use.

4.4 Troubleshoot Physical Connectivity

As you study this section, answer the following questions: > What happens if a host goes down in a star topology? What happens if a host goes down in a token ring topology? > What happens if there is a cable break on a bus topology? What happens is there is a cable break on a dual ring topology? > What is indicated by a flashing green link light? > What might be the problem if none of the NIC lights are working? In this section, you will learn to: > Connect a network cable. > Replace the patch cable. > Replace a faulty cable. > Troubleshoot a faulty cable. > Reconnect a switch. > Troubleshoot a switch. > Connect an unplugged cable. > Troubleshoot an unplugged cable.

4.1 Ethernet

As you study this section, answer the following questions: > What logical topologies are supported on an Ethernet network? > What is the purpose of the backoff on Ethernet networks? > How can you eliminate collisions on an Ethernet network? > What device is used to enable full-duplex communications with Ethernet?

4.3 Connect Network Devices

As you study this section, answer the following questions: > Which cable type would you use to connect a workstation to a regular port on a hub or a switch? > Which cable type would you use to connect a router to the uplink port on a switch? > Which cable type would you use to connect two switches together using their uplink ports? > Which switch feature makes choosing crossover or straight-through cables easier? > When would you use a rollover cable? In this section, you will learn to: > Connect network devices.

The media access control method of all Ethernet networks is __________.

CSMA/CD Carrier sense multiple access with collision detection (CSMA/CD) is the media access control method of all Ethernet networks.

What is the minimum cable specification that supports 1000 Mbps Ethernet?

Cat 5e 1000 Mbps Ethernet (Gigabit Ethernet) requires at least Cat 5e cables. Cat 3 and Cat 4 only support 10 Mbps Ethernet. Cat 5 cable only supports up to 100 Mbps. Cat 6 or Cat 7 is required for bandwidth up to 10 Gbps Ethernet.

What type of cabling is used with 100BaseTX Fast Ethernet networks?

Cat5 or higher Cat5 Ethernet cable or higher can be used with 100BaseTX Fast Ethernet networks.

You want to create a rollover cable that has an RJ45 connector on both ends. How should you connect the wires within the connectors?

Connect pin 1 to pin 8, pin 2 to pin 7, pin 3 to pin 6, and pin 4 to pin 5. When terminated with an RJ45 connector on both ends, the wires within the connectors are rolled over to the opposite connector as follows: Pin 1 connects to pin 8 Pin 2 connects to pin 7 Pin 3 connects to pin 6 Pin 4 connects to pin 5 A crossover cable uses the T568A standard on one end and the T568B standard on the other end. The crossover cable connects pin 1 to pin 3 and pin 2 to pin 6. Connecting each pin to the same pin on the other end creates a straight-through cable.

You need to transfer data from one laptop to another, and you would like to use an Ethernet cable. You do not have a hub or a switch. Which type of cable should you use?

Crossover Use a crossover cable to connect two devices together in a back-to-back configuration. Use a straight-through cable to connect a workstation to a hub or switch port. Use a rollover cable to connect a workstation to the console port of a router or a switch. Use a loopback plug to allow a device to communicate with itself through its own network adapter.

You want to connect the LAN port on a router to the uplink port on a switch. The switch does not support auto-MDI. Which type of cable should you use?

Crossover Use a crossover cable to connect two devices together in a back-to-back configuration. Use a straight-through cable to connect a workstation to a hub or switch port. Use a rollover cable to connect a workstation to the console port of a router or a switch. Use a loopback plug to allow a device to communicate with itself through its own network adapter.

You need to connect two switches using their uplink ports. The switches do not support auto-MDI. Which type of cable should you use?

Crossover Use a crossover cable to connect two switches through their uplink ports or to connect two switches through regular ports. Use a straight-through cable to connect the uplink port on one switch to a regular port on another switch. Use a rollover cable to connect a workstation to the console port of the switch. Use a loopback plug connected to a single port for troubleshooting.

Media Access Method

Ethernet uses a contention-based media access method defined by the IEEE 802.3 standards called Carrier Sense, Multiple Access/Collision Detection (CSMA/CD). Devices use the following process to send data: > Because all devices have equal access (multiple access) to the transmissions media, a device listen to the transmission medium to determine whether it is free before sending data (carrier sense). > If it is not free, the device waits a random amount of time and listens to the transmission medium again. If it is free, the device transmits its message. > If two devices transmit at the same time, a collision occurs. The sending devices detect the collision (collision detection) and send a jam signal to notify all other hosts that a collision has occurred. > Both devices wait a random length of time before attempting to resend the original message (backoff). > Devices with collision detection turned on operate in half-duplex mode; devices with collision detection turned off operated in full-duplex mode.

You have just connected four new computer systems to an Ethernet switch using spare patch cables. After the installation, only three systems are able to access the network. You verify all client network settings and replace the network card in the failed system. The client is still unable to access the network. Which of the following might you suspect is the real cause of the problem?

Failed patch cable Bent and damaged patch cables will prevent client systems from accessing the network. In this scenario, a faulty patch cable is the most likely cause of the connection failure. The easiest way to test this is to simply swap out the cable and try a known working UTP patch cable.

You are moving a client to a new location within an Ethernet network. Previous to the move, the client system did not have difficulty accessing the network. During the relocation, you attach patch cables from the client system to the wall jack and from the patch panel to the switch. Once connected, you do not get a link light on the network card or the switch. You swap out the cable running between the patch panel and the switch with a known working one, but you still cannot connect. Which of the following might you suspect is the problem?

Failed patch cable between the client system and the wall jack Because the client system previously worked in a different location, the issue is not likely related to the client system. The NIC and switch LEDs' failure to light indicate that there isn't an end-to-end connection between the client and the switch. This means that either the patch cable between the wall jack and the client is faulty or the cable between the patch panel and the switch faulty. The cable connecting the switch and the patch panel was verified, leaving the cable run between the wall jack and the client system. It is unlikely that the issue is a failed network card, as the system was functioning in a different location, eliminating the possibility of hardware and software on the client system being the problem. The failure is limited to a connection issue between a single client and a switch. If the switch failed, all clients connected to that switch would not be able to connect. Incorrect duplex settings would not prevent NIC and switch LEDs from lighting.

Upon conducting a visual inspection of the server room, you see that a switch displays LED collision lights that are continually lit. You check the LED on the corresponding workstation and see that it is flashing rapidly even though it is not sending or receiving network traffic at that time. What is the cause of the network collisions?

Faulty network card Sometimes when a NIC fails, it doesn't just stop working, but begins to flood the network with transmissions. This is called jabbering. A single network card can slow down and entire network by continually transmitting onto the network. A jabbering network card can be identified by a slower than normal network, by high occurrences of collisions displayed on the hub or switch, and by LEDs on a network card indicating a high level of transmissions even though a user is not using the network.

Fiber Optic Cable

Fiber optic cable is a high-speed data transmission medium. It contains tiny glass or plastic optical fibers that carry light beams. Digital data is transmitted through the cable via rapid pulses of light.

Users are complaining that sometimes network communications are slow. You use a protocol analyzer and find that packets are being corrupted as they pass through a switch. You also notice that this only seems to happen when the elevator is running. What should you do?

Install shielded cables near the elevator. Interference is a signal that corrupts or destroys regular networking signals. Interference affects the availability of a network because normal communications are not possible. Sources of interference include elevators, generators, motors, and fluorescent lights. Use a UPS or a dedicated power circuit to ensure that devices have constant power. Use a dedicated A/C unit to keep a server room or closet cool.

Light Link - Unlit Activity - Unlit Collision - Unlit

Meaning - The network card does not have a connection to the network. The link light only activates when the computer detects a connection to another device. If the link light is off, possible causes include the following: > Bad NIC > Faulty Cable > Missing device on the other end (unplugged cable) > Switch or hub port turned off or bad

You have a network connected using a physical bus topology. One of the cables that connects a workstation to the bus breaks. Which of the following best describes what effect this will have on network communications?

No devices will be able to communicate. A break in the network bus means that the end of the network bus is no longer terminated. For this reason, a break in the bus typically means that no devices can communicate. Identifying the location of the break is difficult on a true bus network.

Which of the following are requirements of the 1000BaseT Ethernet standards? (Select three.)

RJ45 connectors The cable length must be less than or equal to 100m Cat 5e cabling Gigabit Ethernet (1000BaseT) has similar requirements to 100BaseT with connectors, cabling, and distances. The network cards are simply designed to transfer data ten times as fast.

Which of the following standards is typically used in a rollover cable?

RS232 A rollover cable has a serial connector on one end and an RJ45 connector on the other end. RS232 is the standard for serial communications. RJ11 connectors are used for analog telephone lines. RG6 and RG58 are coaxial cable standards.

Which of the following connectors is typically used on one end of a rollover cable?

Serial A rollover cable has a serial connector on one end and an RJ45 connector on the other end. Alternatively, it might have an RJ45 connector on both ends and use a serial converter to convert from the RJ45 connector to a serial connector. BNC and F-type connectors are used with coaxial cables. ST, SC, and LC connectors are used with fiber optic cables.

You would like to implement 10 Gbps Ethernet over a distance of 1 kilometer or greater. Which of the following would be the minimum requirement for the implementation? (Select two.)

Single-mode fiber 10GBaseLR standards For 10 Gbps at distances up to 10 kilometers, use 10GBaseLR with single-mode fiber. Multi-mode fiber is cheaper, but has a shorter maximum distance than single-mode fiber. 10GBaseSR uses multi-mode fiber at distances up to 300 meters. 10GBaseER supports distances up to 40 kilometers using single-mode fiber.

Gigabit Ethernet

Standard - 1000BaseCX (Short Copper) Bandwidth - 1000 Mbps (half-duplex) | 2000 Mbps (full-duplex) Cable Type - Special Copper (150 ohm) Maximum Segment Length - 25 meters used in wiring closets. Standard - 1000BaseSX (Short) Bandwidth - 1000 Mbps (half-duplex) | 2000 Mbps (full-duplex) Cable Type - Fiber Optic Maximum Segment Length - 220-550 meters depending on cable quality. Standard - 1000BaseLX (Long) Bandwidth - 1000 Mbps (half-duplex) | 2000 Mbps (full-duplex) Cable Type - Fiber Optic Maximum Segment Length - 550 meters 5 kilometers

Ethernet

Standard - 10BaseFL Bandwidth - 10 Mbps (full-duplex) Cable Type - Fiber Optic Maximum Segment Length - 1000-2000 meters

10 Gigabit Ethernet

Standard - 10GBaseLR Bandwidth - 10 Gbps (full-duplex only) Cable Type - single mode fiber optic Maximum Segment Length - 10 kilometers

Which of the following physical topologies are used with Ethernet networks? (Select two.)

Star Bus Ethernet networks use either a physical bus or physical star topology. Hubs can also be cascaded to form a tree topology.

CRC

The cyclic redundancy check (CRC) is the result of a mathematical calculation performed on the frame. The CRC helps verify that the frame contents have arrived uncorrupted.

A network is connected following the IEEE 802.3 specifications. Which of the following best describes when a device can transmit messages?

The device listens to determine if the transmission media is free. The IEEE 802.3 committee describes the CSMA/CD media access method. Devices listen to the network to determine if the transmission media is free before transmitting.

4.4.8 Troubleshoot Physical Connectivity 3

You are a network technician for a small corporate network. Minutes ago, your entire building had a power blackout. The power has been partially restored, but there are still offices and closets without power. Employees in the Executive Office and the Support Office have called to report that they cannot access the internet or other computers on the network. You need to diagnose and fix the problem as it pertains to the network. Complete this lab as follows: Move the power supply for the Switch in the Networking Closet to the empty critical load bank on the USP.

4.4.6 Troubleshoot Physical Connectivity 1

You are a network technician for a small corporate network. The employee in Office 1 says he cannot communicate with the computer in Office 2, and has asked that you come to his office to fix the problem. Complete this lab as follows: In the Networking Closet, replace the patch cable for Office 2

4.4.9 Troubleshoot Physical Connectivity 4

You are a network technician for a small corporate network. The employee in Office 1 says that after she added a pair of speakers to her workstation, she could no longer communicate with the computer in the Networking Closet. You need to diagnose and fix the problem. In Office 1, plug the network cable back into the motherboard's NIC and confirm the connection to the network and the Internet

4.2.3 Reconnect to an Ethernet Network Lab

You are a network technician for a small corporate network. The employee in Office 2 reported that she can no longer communicate with other workstations on the local network or the internet. After troubleshooting the problem, you determine that the built-in network card in the workstation has stopped working. In this lab, your task is to complete the following: > On the Office 2 workstation: - Select and install a new networking card that provides Fast Ethernet speeds (a faster network card is not required). - Connect the workstation to the local network using the appropriate cable. > On the Office2 workstation, confirm that the workstation has a connection to the local network and the internet. Complete this lab as follows: 1. Above the computer, select Motherboard to switch to the motherboard view of the computer. 2. In the Power Off warning, select Yes to turn off the computer. 3. On the Shelf, expand Network Adapters. 4. Identify the network adapter that supports Fast Ethernet 100BaseTX. 5. On the Shelf, drag the 100BaseTX network adapter to a free PCI slot on the computer. The 100BaseTX network adapter supports Fast Ethernet, which is all that is required. 6. Connect the computer to the network as follows: a. Above the computer, select Back to switch to the back view of the computer. b. Drag the Cat5 cable connector from the motherboard's NIC to the port of the 100BaseTX network adapter. 7. Verify the connection to the local network and the internet as follows: a. Above the computer, select Front to switch to the front view of the computer. b. Click the power button on the computer case. c. After the workstation's operating system is loaded, right-click the Network icon in the notification area and select Open Network and Sharing Center. The diagram should indicate an active connection to the network and the internet. *You can also confirm the speed of the connection by clicking Ethernet in the Network and Sharing Center.

4.4.7 Troubleshoot Physical Connectivity 2

You are a network technician for a small network. The manager in the Support Office says she can't communicate with any computer in the network. You need to diagnose and fix the problem. Complete this lab as follows: In the Support Office, add a new NIC and connect the Ethernet cable to the new NIC

4.3.3 Connect Network Devices Lab

You're a network technician for a small corporate network. The company recently expanded to the second floor of its building. You've already installed a small networking closet on the second floor, and you've run the necessary cables to the ports on each of the floor's fiber patch panels. Now, you need to connect the two networks using fiber optic cables. In this lab, your task is to connect the switch in the Networking Closet on Floor 1 with the switch in Networking Closet 2 on Floor 2 through the fiber patch panels in each networking closet. Use the following information to identify the necessary connections: > Connect the appropriate fiber cable to switches through the fiber patch panels. > For the patch panel on Floor 1: - Port 3 is transmit (Tx). - Port 4 is receive (Rx). > For the patch panel on Floor 2: - Port 1 is transmit (Tx). - Port 2 is receive (Rx). > Use the color coding on the end of fiber optic cables to identify which end is Tx and which is Rx. - Connector A (white or red) is Tx. - Connector B (black) is Rx. > Plug the switch on Floor 2 into a bank 1 critical load outlet on the UPS. > Verify the connection was made by checking the internet connection on any Floor 2 computer. *When you connect fiber optic cables, the transmit (Tx) port on one device is connected to the receive (Rx) port on the other device. The fiber cables in this lab have already had their Rx and Tx connectors switched as necessary. You can view component information in the Details window on the Specification tab. Complete this lab as follows: 1. On the Shelf, expand the Adapters category. 2. Drag the SFP Transceiver (LC) to an open SFP port on the switch. 3. Connect the fiber cable to switches on Floor 1 as follows: a. On the Shelf, expand Cables. b. Drag the SC to LC fiber cable to the SFP LC port on the switch. c. In the Select Connector window, select the LC connector. d. In the Selected Component pane, drag the SC Connector (A) to port 3 on the fiber patch panel. e. In the Selected Component pane, drag the SC Connector (B) to port 4 on the fiber patch panel. 4. Connect the fiber cable to switches on Floor 2 as follows: a. From the top menu, select Building A. b. Under Building A, select Floor 2. c. Under Networking Closet 2, select Hardware. d. On the Shelf, expand Adapters. e. Drag the SFP Transceiver (LC) to an open SFP port on the switch. f. On the Shelf, expand Cables. g. Drag the SC to LC fiber cable to the SFP LC port on the switch. h. In the Select Connector window, select the LC connector. i. In the Selected Component pane, drag the SC Connector (A) to port 1 on the fiber patch panel. j. In the Selected Component pane, drag the SC Connector (B) to port 2 on the fiber patch panel. 5. Plug the switch on Floor 2 into a bank 1 critical load outlet on the UPS as follows: a. Above the rack, select Back to switch to the back view of the rack. b. On the Shelf, drag the AC Power Cable. c. In the Select Connector window, drag AC Power Connector (Female) to the AC port on the back of the switch. d. In the Selected Component pane, drag the AC Power Connector (Male) to an open bank 1 critical load outlet. e. Above the rack, select Front to switch to the front view and confirm the network switch has power. 6. Verify that there is an internet connection for any Floor 2 computer as follows: a. From the top menu, select Floor 2. b. Select any of the computers on Floor 2. c. In the notification area, right-click the Network icon and select Open Network and Sharing Center. d. Confirm that the computer has an internet connection. 7. Click Done to finish the lab. To determine the appropriate network components to use, examine the ports on the switch and the fiber patch panel. Because the switch doesn't have a fiber port, the SFP module with the LC fiber connector must be used. The only cable that can be used to connect the switch and the server is the SC to LC fiber cable. When connecting the fiber cable to the patch panel: On Floor 1: Connect SC Connector A to port 3. Connect SC Connector B to port 4. On Floor 2: Connect SC Connector A to port 1. Connect SC Connector B to port 2.