Cabling LANs and WANs

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Cabling LANs and WANs

• Week 5
• Directed Reading Chapter 4 of Cisco CCNA 1
  Companion Guide
• For those doing the Cisco test read whole chapter
  including testing
• Otherwise reading is page 205 onwards

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Format of Lecture

• Issues with cabling LANs
• Types of equipment/choices
• LAN cabling and Networking Models
• Peer to Peer
• Client/Server
• Issues with cabling WANs
• Setting up a console session (relates to lab
  sheet next week)

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Issues the business case

• Last week we discussed the different types of
  media which exist e.g. copper, UTP, fibre and how
  we can compare them with each other using cost,
  length and installation
• This week we need to prepare you for the tutorial
  where you use your last weeks build of two types
  of cable which are crossover and straight
  through
• Why did you build them? What do you connect them
  to?
• This is a design issue what type of network
  does the customer want?

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Crossover cable reminder

• CROSSOVER cables connect 2 PCs directly together
• You built one of these in the labs last week
• They cannot be used to connect from a PC to a hub
  or switch or router a different type of cable
  is used for that - a straight through

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But why a Crossover?

• To connect similar devices
• Eg PC to PC
• Switch to Switch
• Switch to hub

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What to connect

• There are strict rules as to which cables work
  with what type of connection
• You cannot just put any cable into a device in a
  random manner you must first check it is
  appropriate for the connection you intend to
  insert it into

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Cabling in LANs Ethernet

• Most widely used LAN technology
• Ethernet 10BaseT what this mean? 10Mbps speed
• End-user level
• Low to medium volume applications
• Fast Ethernet what this mean? 100Mbps speed
• Gigabit Ethernet
• Mainly in backbone and network device
  connectivity using either fibre or UTP

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Ethernet Connectivity Recommendations

• End-user level 10BASET
• Workgroup level Fast Ethernet
• Backbone either Fast Ethernet or Gigabit
  Ethernet
• Refer to chapter 4 page 207

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Cat 5 UTP and RJ45 Jack
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Connection Media back of router

• 15-pin attachment unit interface (AUI) connector
  (DB15) allows different media to connect when
  used with the appropriate transceiver.
• Transceiver is an adapter that converts one type
  of connection to another.
• Typically, a transceiver converts an AUI to
  RJ-45, coax, or fibre optic connector.

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UTP Implementation

• 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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LAN Client and Servers

• Relationship between Workstation and Server
• Request and Response model
• Different models available
• Peer-to-Peer (Workgroups)
• Client/Server

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Peer to peer Environment
Ethernet line

• Each computer can take on the client function or
  the server function
• At one time, computer A may make a request for a
  file from computer B, which responds by serving
  the file to computer A. Computer A functions as
  client, while B functions as the server. At a
  later time, computers A and B can reverse roles.
• Individual users control their own resources.
• The users may decide to share certain files with
  other users. The users may also require passwords
  before allowing others to access their resources.
  

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A question

• When is a peer to peer environment appropriate?
• Simple network
• No need for specialist equipment
• Most operating systems support peer to peer
• Implies equality workstation acts as a client
  but can also provide a service (server) to other
  workstations
• Cheap

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Advantages of Peer to Peer?

• Individual users control their own resources no
  central control
• They can decide to share files
• Allocate passwords to files
• Users responsible for housekeeping their machine

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Disadvantages of Peer to Peer?

• No central control scope for inconsistent
  housekeeping
• A poorly maintained workstation may become a weak
  link for the other peers it occasionally serves
• Scalability no suitable for large network
• Becomes difficult to manage/co-ordinate
• Efficiency in relationship with how many
  computers are on the network
• Business case ideal for SMEs or home use

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Cabling Peer to Peer

• Which cable do we use to connect one peer to
  another?
• Crossover
• You will do this in the lab this week

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Hub-Based Network

• Use of a Ethernet Hub
• Why? need to remind ourselves what a hub does
• All ports of the LAN can see a packet no
  filtering
• Hubs used as a common connection point for
  devices in a network (useful for segmenting a
  network)
• Lab exercise this week
• Cables used
• Straight through cable between hub and
  workstation A
• Straight through cable between hub and
  workstation B

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Switch-Based Network

• Use of an Ethernet switch
• Why? Lab exercise achieves the same thing but
  need to remind ourselves what a switch does
• Filters and forwards based on Mac addresses
• Lab exercise this week
• Cables used
• Straight through cable between switch and
  workstation A
• Straight through cable between switch and
  workstation B

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Client and 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.
• 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.
  This is done by assigning each client an account
  name and password that is verified by an
  authentication service.

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Client/Server

• Those of you interested in this model of
  networking should be enrolled on Semester 2
  Client/Server Systems module
• Client/Server is a model used by the Internet
• The SOC use this model
• I use this model for my servers in LC26
• Stokejava
• StokeXML
• Tomcat server

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A Question

• When is a client/server environment appropriate?
• Multi-user access to distributed resources
• Security
• Central control

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Advantage of C/S?

• Control and management easier
• Flexible
• Server Side processing

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Disadvantages of C/S?

• Trade off of control versus cost
• Servers more expensive than clients
• Reliability of server (s) needs to be consider

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Cabling the WAN

• WAN connecting one network to other remote
  networks
• Different connection methods to LANs
• Cabling standards different to LANs
• Essentially cabling and connectors used to
  interconnect switches and routers in a LAN and WAN

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WAN Physical Implementations
Point to Point Protocol
Choice depends on the distance, speed
See page 232 V3 Cisco CCNA 1 book
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Choice of WAN Connection - line

• Leased Line Routers
• Dedicated
• High speed
• Serial connection
• Dial-up ISDN router
• ISDN
• Broadband routers
• DSL over existing twisted pair telephone lines
  (ADSL)
• Cable modems uses coaxial cable (cable
  television)

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WAN cabling choices

• Serial cables selection of correct type to use
  with the router depends on WAN interface card -
  a popular cable is a V.35
• Table 4-6 page 233 has a summary
• We will be doing a practical with WAN cables in
  later tutorials

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DCE and DTE!!!

• Data Communications Equipment (DCE)
• Data Terminal Equipment (DTE) a router linking
  to a end user device e.g. workstation
• DCE converts user data from a DTE device into a
  form compliant with the WAN provider

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WAN Serial Connections
Typical Scenario

• For long distance communication, WANs use serial
  transmission. This is a process by which bits of
  data are sent sequentially over a single channel.
• If the connection is made directly to a service
  provider, or to 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.
• Data communications equipment (DCE) cable
  provides clocking rate to end-user devices

Modem
WAN
Synchronisation
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Serial Implementation of DTE and DCE
Jcw Ltd
MChai Ltd
WAN Service
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Back-to-Back Serial Connection
This slide is just to say that in some Cases a
router could be a DCE Instead of DTE. In this
diagram routers are being Used at both ends of
the connection One is DTE and the other DCE Why
this is to simulate/test a WAN service
Serial line
Console session using rollover cable
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Familiarisation of a router Fixed Interfaces
(ports) of a router
Obviously we will get to Use our routers in LC123
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Modular Serial Interfaces (ports)
The essential point Is that routers can
have Modular cards and can Be configured for the
Type of WAN service
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Routers and DSL connections
phone cable

• Use phone cable with RJ11 connectors to
• Connect the phone cable to the ADSL port on the
  router.
• Connect the other end of the phone cable to the
  phone jack.

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Setting up a Console Connection this is a
subject for next week!

• 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.
• 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.

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Conclusion

• We have discussed that there are choices of how
  we use our cables
• Based on equipment we intend to use
• How equipment talks to other equipment for
  example router to router
• LANs and WANs have different characteristics
• A WAN is made up from LANs
• WANs routers for communication