1. Module 5: Cabling LANs and WANs
James Chen
2018/9/22
Yuda College of Business

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Outline
5.1 Cabling the LAN
LAN physical layer
Ethernet in the campus
Ethernet media and connector requirements
Connection media
UTP implementation
Repeaters
Hubs
Wireless
Bridges
Switches
Host connectivity
Peer-to-peer
Client/server
5.2 Cabling the WAN
WAN physical layer
WAN serial connections
Routers and serial connections
Routers and ISDN BRI connections
Routers and DSL connections
Routers and cable connections
Setting up console connections
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5.1 Cabling the LAN
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LAN physical layer
Various symbols are used to represent media types.
Each media has advantages and disadvantages.
Some of the advantage or disadvantage comparisons concern:
Cable length
Cost
Ease of installation
Susceptibility (敏感性)to interference
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Ethernet in the campus
Ethernet is the most widely used LAN technology.
IEEE specification is released in 1980.
IEEE extended to three new committees
802.3u (Fast Ethernet)
802.3z (Gigabit Ethernet over Fiber)
802.3ab (Gigabit Ethernet over UTP)
The new generation applications can easily overwhelm (淹沒)a network bandwidth (10M/100M).
Conceder providing GE from the backbone to the end user ?
GE to the desktop is not a standard installation now.
Ethernet technologies in campus network
User level (10Mbps) / Clients or servers (100Mbps)
link between user and network devices
Fast Ethernet can be used to connect enterprise servers.
Fast Ethernet or Gigabit Ethernet, as affordable, should be implemented between backbone devices.
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6. Ethernet in the campus (cont.)
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7. Ethernet media and connector requirements
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Connection media
A transceiver is an adapter that converts one type of connection to another.
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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.
Four of the wires carry the voltage and are considered “tip” (T1 through T4).
The other four wires are grounded and are called “ring” (R1 through R4).
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, and so on.
Use straight-through cables for the following cabling:
Switch to router
Switch to PC or server
Hub to PC or server
Use crossover cables for the following cabling:
Switch to switch
Switch to hub
Hub to hub
Router to router
PC to PC
Router to PC
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10. UTP implementation (cont.)
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11. UTP implementation (cont.)
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12. UTP implementation (cont.)
Lab RJ-45 Jack Punch(用力按)Down
The process of punching down wires into a data jack in an office area is the same as punching them down in a patch panel in a wiring closet.
The following resources are required:
cm (2 - 3 feet) length of Category 5/5e cabling, which can be one per person or one per team
Two Category 5/5e RJ-45 data jacks (one extra for spare) – If RJ-45 data jacks are installed on both ends of the cable, the installation can be tested by inserting cable with RJ-45 connectors and a simple cable continuity tester.
Category 5/5e wall plate
110 type punch-down tool
Wire cutters
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Repeaters
The purpose of a repeater is to regenerate and retime network signals at the bit level. This allos them to travel a longer distance on the media.
No more than four repeaters can be used between hosts on a LAN.
To limit latency added to frame travel by each repeater.
Too much latency on the LAN increases the number of late collisions and makes the LAN less efficient.
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Hubs
Hubs are actually multiport repeaters.
Star topology
With hubs, data arriving over the cables to 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 was sent. (broadcast)
Hubs come in three basic types:
Passive hub
It serves as a physical connection point only.
It is used only to share the physical media.
It does not need electrical power.
Active hub
Electrical power id needed.
It amplify the incoming signal before passing it out to the other ports.
Regenerate / retime
Intelligent hub
Smart hubs
It basically function as active hubs
Microprocessor chip
Diagnostic capabilities
Useful in troubleshooting situations.
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Hubs (cont.)
Devices attached to a hub receive all traffic traveling through the hub.
more devices > more collisions.
A collision occurs when two or more workstations send data over the network wire at the same time. All data is corrupted when that occurs.
Every device connected to the same network segment is said to be a member of a collision domain.
Sometimes hubs are called concentrators, because hubs serve as a central connection point for an Ethernet LAN.
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Wireless
Wireless data communication
for mobile applications or users
ex: commuters(通勤者), airplanes, satellites, remote space probes, space shuttles, and space stations.
Two wireless technologies used for networking :
IR(InfraRed)
All devices must be in the line of sight of the transmitter in order to operate.
New IR technologies being developed that can work out of sight.
RF(Radio Frequency)
Outside interference and geographic obstructions(阻塞物)
The limited range of radio signals restricts the use of this kind of network.
RF technology can be on single or multiple frequencies.
Frequency Hopping Spread Spectrum (FHSS) / Direct Sequence Spread Spectrum (DSSS).
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Bridges
There are times when it is necessary to break up a large LAN into smaller, more easily managed segments.
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 blocks the frame from going on to 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. (泛濫)
If placed strategically, a bridge can greatly improve network performance.  
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Bridges (cont.)
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Bridges (cont.)
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Switches
A switch is sometimes described as a multiport bridge.
In data communications today, all switching equipment performs two basic operations.
The first operation is called switching data frames.
The second is the maintenance of switching operations where switches build and maintain switching tables and search for loops.
It supports new functionality, such as virtual LANs.
An Ethernet switch has many benefits.
One benefit is that an Ethernet switch allows many users to communicate in parallel 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 moving to a switched LAN environment is very cost effective because existing hardware and cabling can be reused.
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Switches (cont.)
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Switches (cont.)
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Host connectivity
The function of a NIC is to connect a host device to the network medium.
NICs are considered Layer 2 devices.
It has a unique MAC address on it.
When the type of connector on the NIC does not match the type of media, a transceiver is needed.
A transceiver converts one type of signal or connector to another. It is considered a Layer 1 device because it only works with bits, and not with any address information or higher-level protocols.
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Peer-to-peer
In a peer-to-peer network, networked computers act as equal partners, or peers.
Each computer can take on the client function or the server function.
In a peer-to-peer network, individual users control their own resources.
Peer-to-peer networks are relatively easy to install and operate.
A peer-to-peer network works well with 10 or fewer computers.
The security may be difficult to maintain.
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Client/server
Servers are designed to handle requests from many clients simultaneously and continuously available to respond to requests from clients. (ex: file, print, application, and other services)
Typically, desktop computers function as clients, one or more computers with additional processing power, memory, and specialized software function as servers.
The client must be identified and be authorized to use the server resource. (ex: account name and password for resources)
With the centralization of user accounts, security, and access control, server-based networks simplify the administration of large networks.
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Client/server (cont.)
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Client/server (cont.)
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5.2 Cabling the WAN
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WAN physical layer
The physical layer implementations vary depending on the distance of the equipment from the services, the speed, and the type of service itself.
Serial connections are used to support WAN services such as dedicated leased lines that run Point-to-Point Protocol (PPP) or Frame Relay.
T1 service at Mbps
E1 service at 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.
Broadband high-speed services
DSL service can achieve T1/E1 speeds over the existing telephone line.
Cable services use the existing coaxial cable TV line. A coaxial cable line provides high-speed connectivity matching or exceeding that of DSL.
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30. WAN physical layer (cont.)
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31. WAN serial connections
For long distance communication, WANs use serial transmission.
For a Cisco router, there are 2 types of physical serial connectors at the customer site.
60-pin connector (V.35)
‘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.
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, the connection will consist of a DCE and a DTE cable.
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32. WAN serial connections (cont.)
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33. WAN serial connections (cont.)
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34. Routers and serial connections
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.
To configure a port on a modular card, it is necessary to specify the interface using the syntax “port type slot number/port number.” (ex: “serial 1/0,” slot 1/ port 0)
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35. Routers and serial connections (cont.)
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36. Routers and serial connections (cont.)
back-to-back router scenario in a test environment
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37. Routers and serial connections (cont.)
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38. Routers and serial connections (cont.)
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39. Routers and ISDN BRI connections
With ISDN BRI, 2 types of interfaces may be used, BRI S/T and BRI U.
An Network Termination 1 (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.
It may be necessary to provide an external NT1 if the device is not already integrated into the router.
Labeling on the router interfaces
BRI U (with integrated NT1)
BRI S/T (without integrated NT1)
Routers can have multiple ISDN interface types, determine which interface is needed when the router is purchased.
Use a UTP Category 5 straight-through cable to interconnect the ISDN BRI port to the service-provider device.
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.
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40. Routers and ISDN BRI connections (cont.)
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41. Routers and DSL connections
The Cisco 827 ADSL router has one asymmetric digital subscriber line (ADSL) interface.
Connect the phone cable (with RJ-11 connectors) from the ADSL port on the router to the phone jack on the wall.
DSL works over standard telephone lines using pins 3 and 4 on a standard RJ-11 connector.
PS… Low-pass filter (or splitter) is needed for telephone.
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42. Routers and cable connections
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.
Connect the coaxial cable from the F connector of the router to the coaxial cable (TV) wall outlet.
Hand-tighten the connector, making sure that it is finger-tight, and then give it a 1/6 turn with a wrench.
If needed, install a cable splitter/directional coupler for TV and computer use.
If necessary, also install a high-pass filter to prevent interference between the TV and computer signals.
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43. Setting up console connections
The console port allows monitoring and configuration of a Cisco hub, switch, or router.
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.
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44. Setting up console connections (cont.)
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