Chapter 10 Planning and Cabling Networks

1. CCNA Exploration Network Fundamentals Chapter 10 Planning and Cabling Networks

2. hub switch switch router router Routers • Primary devices used to interconnect networks • each port on a router connects to a different network and routes packets between networks • Have the ability to break up broadcast domains (BD) and collision domains (CD) • Used to interconnect networks that use different technologies • LAN and WAN interfaces

3. Hubs • A hub receives a signal, regenerates it, and sends the signal over all ports • ports use a shared bandwidth approach • reduces the LAN performance due to collisions and recovery • maintains a single collision domain • Used in a small LAN that requires low throughput requirements or when finances are limited • Less expensive than a switch

4. Switches • A switch receives a frame and regenerates each bit of the frame on to the appropriate destination port • Used to segment a network into multiple collision domains • Each port on the switch creates a separate collision domain • creates a point-to-point logical topology to the device on each port • provides dedicated bandwidth on each port • Can be used to interconnect network segments of different speeds

5. Device Selection Factors • Cost • Speed and types of ports/interfaces • Expandability • Manageability • Additional features and services

6. Factors to Consider in Choosing a Switch • Cost • its capacity and features • network management capabilities, embedded security technologies and optional advanced switching technologies • Simple “cost per port” calculation • deploy one large switch at a central location • cost savings may be offset by the expense from the longer cables • Compare the cost of deploying a number of smaller switches connected by a few long cables to a central switch

7. Factors to Consider in Choosing a Switch (cont’d) • Investing in redundancy • a secondary switch to operate concurrently with the primary central switch • additional cabling to allow the physical network to continue its operation even if one device fails

8. Speed and Type of Ports (Interfaces) • Purchasing decisions • just enough ports for today’s needs • mixture of UTP speeds • both UTP and fiber ports

9. Factors to Consider in Choosing a Router • Expandability • modular devices have expansion slots that provide the flexibility to add new modules as requirement evolve • basic number of fixed ports as well as expansion slots • Media • additional modules for fiber optics can increase the cost • Operating system features • different versions of the operating system support certain features and services • security, quality of service, voice over IP, routing multiple Layer 3 protocols, NAT and DHCP

10. LAN Cabling Areas • Work area • Telecommunication room, also known as distribution facility • Backbone cabling, also known as vertical cabling • Distribution cabling, also known as horizontal cabling

11. LAN Cabling Areas (cont’d) • Cable length • ANSI/TIA/EIA-568-B standard for UTP installations • maximum distance of 100 meters per channel • up to 5 meters of patch cable for interconnecting patch panels • up to 5 meters of patch cable from the cable termination point on the wall to the computer and telephone • Work area • end user devices are located • minimum of two jacks • patch cables, which are straight-through UTP cables, are used to connect end user devices to the wall jacks • EIA/TIA standard specifies the UTP patch cords to connect devices to the wall jacks have a maximum length of 10 meters • a crossover cable is used to connect a switch or hub to the wall jack

12. LAN Cabling Areas (cont’d) • Telecommunications room • contains the intermediary devices – hubs, switches, routers and data service units (DSUs) • where connections to intermediary devices take place • these devices provide the transitions between the vertical (or backbone) cabling and the horizontal cabling • patch cords are used to connect patch panels and intermediary devices • servers are also housed in the telecommunication room • Horizontal cabling • refers to cables connecting the telecommunication rooms with the work areas • maximum cable length from a termination point in the telecommunication room to the termination at the work area outlet must not exceed 90 meters

13. LAN Cabling Areas (cont’d) • Vertical cabling • refers to the cabling used to connect the telecommunication rooms to the equipment rooms • also interconnects multiple telecommunication rooms throughout the facility • used for aggregated traffic, such as traffic to and from the Internet access to corporate resources at a remote location • typically require high bandwidth media such as fiber-optic cabling

14. Types of Media • UTP (Category 5, 5e, 6 and 7) • Fiber optics • Wireless

15. Choosing a Media • Cable length • does the cable need to span across a room or from a building to a building? • Cost • does the budget allow for using a more expensive media type? • Bandwidth • does the technology used with the media provide adequate bandwidth? • Ease of installation • does the implementation team have the ability to install the cable or is vendor required? • Susceptible to EMI/RFI • is the local environment going to interfere with the signal?

16. Cable Length • Total length of cable • all cables from the end devices in the work area to the intermediary device, usually a switch, in the telecommunication room • cable from the devices to the wall plug, through the building from the wall plug to the cross-connect (or patch panel) and from the patch panel to the switch • Signal attenuation and exposure to possible interference increase with cable length • the horizontal cabling length for UTP needs to stay within the recommended maximum distance of 90 meters

17. Ethernet Cabling Standards

18. Cable Cost and Bandwidth • Cost • depend on media type such as copper or fiber optic • budget for fiber-optic cabling • installation costs for fiber are significantly higher • match the performance needs of the users with the cost of the equipment and cabling to achieve the best cost/performance ratio • Bandwidth • devices in a network have different bandwidth requirements • select a media that will provide high bandwidth, and can grow to meet increased bandwidth requirements and newer technologies

19. Cable Installation • Ease of cable installation varies according to cable types and building architecture • access to floor or roof spaces • physical size and properties of the cable • Cables are usually installed in raceways • a raceway is an enclosure or tube that encloses and protects the cable • UTP cable is relatively lightweight and flexible and has a small diameter • can fit into small spaces • Fiber-optic cables contain a thin glass fiber • crimps or sharp bends can break the fiber • Wireless networks require less cabling

20. Types of Interference • Electromagnetic interference (EMI) • undesirable disturbance that affects an electric circuit due to electromagnetic radiation emitted from an external source such as electrical machines and lighting • Radio frequency interference (RFI) • radio frequency signals transmitted from nearby radio stations that interfere with the operating frequency of the equipment • Wireless is the medium most susceptible to RFI • potential sources of interference must be identified

21. UTP Cabling Connections • Specified by the Electronics Industry Alliance/Telecommunications Industry Association (EIA/TIA)

22. Types of Interfaces • Media-dependent interface (MDI) • pins 1 and 2 are used for transmitting • pins 3 and 6 are used for receiving • devices such as computers, servers or routers have MDI connections • Media-dependent interface, crossover (MDIX) • devices that provide LAN connectivity such as hubs or switches use MDIX connections • MDIX connections swap the transmit-receive pairs internally • end devices connect to hubs or switches using straight-through cables

23. Straight-Through UTP Cables • A straight-through cable has the same termination at each connector end • in accordance with either the T568A or T568B standards • Use the same color codes throughout the LAN for consistency in documentation • Used for connecting different types of devices • switch to router Ethernet port • computer to switch • computer to hub

24. Cross-over UTP Cables • A cross-over cable has T568A termination at one end and a T568B termination at the other end • transmit pins at each end connect to the receive pins at the other end • Used for connecting same types of devices • switch to switch • switch to hub • computer to router Ethernet port • router to router Ethernet port • computer to computer

25. LAN Connections • Straight-through UTP cables are used for connecting different types of devices, such as a router LAN interface to a switch • Cross-over UTP cables provide connections between same type of devices, such as a switch to another switch

26. MDI/MDIX Selection • On some devices, ports may have a mechanism that electrically swaps the transmit and receive pairs • engage the mechanism to change the port setting • Some devices allow for selecting whether a port functions as MDI or MDIX during configuration • Many newer devices have an automatic crossover feature • device detects the required cable type and configures the interface • auto-detection can be enabled by default or via configuration command

27. WAN Connections • WAN links span extremely long distances • over wide geographic areas • The chart shows some examples of WAN connections • telephone line RJ-11 connectors for dial-up or DSL connection • coaxial cable F connector for cable connection • serial connections

28. Smart serial DB-60 Winchester block Smart serial Serial Cables • One end of the serial cable is either a smart serial connector or a DB-60 connector • The other end is a large Winchester 15-pin connector • V.35 connection to a Physical layer device such as a CSU/DSU

29. Types of Devices • Data terminal equipment (DTE) • a device that receives clocking services from another device • device is usually at the customer or the user end of the link • Data communications equipment (DCE) • a device that supplies the clocking service to another device • device is typically at the WAN access provider end of the link

30. Serial WAN Connections in the Lab • Routers are DTE devices by default, but they can be configured to act as DCE devices • Two routers can be connected together using a serial V.35 cable • V.35 cables are available in DTE and DCE versions

31. Determining the Number of Hosts • Every device needs an IP address • consider present and future needs • Segment the network based on host requirements • number of hosts in a network or subnetwork is 2h – 2

32. Segmenting a Network • Manage broadcast traffic • divide one large broadcast domain into a number of smaller domains • not every host need to receive every broadcast • Different network requirements • group users that share similar network or computing facilities together in one subnet • Security • implement different levels of network security based on network addresses

33. subnet 0 subnet 1 subnet 2 subnet 3 subnet 4 Creating Subnets • Each subnet, is a physical segment, requires a router interface as the gateway for that subnet • Number of subnets on one networks is determined using 2n • n is the number of bits “borrowed” from the host bits to create subnets • Fixed length subnet mask • one subnet mask for the entire network • each physical segment is assigned an unique subnet • each subnet has a same number of usable (or valid) host addresses

34. Designing an Address Standard • Use addresses that fit a common pattern across all subnets can assist troubleshooting and expedite adding new hosts • Hosts can be categorized as general users, special users, network resources, router LAN interfaces, router WAN links and management access • Document the IP addressing scheme

35. Calculating Addresses Case Study 1

36. Network Topology

37. Network Requirements • WAN link • router-to-router connection requires 2 host addresses • There are 4 subnetworks in this topology • student, instructor, administrator and WAN

38. Fixed Length Subnet Mask • Require 9 host bits to support the largest number of host addresses • 29 – 2 = 510 usable host addresses • subnet mask is 255.255.254.0 (or /23 prefix) • 2 bits are assigned for subnets  22 = 4 subnets

39. Variable Length Subnet Mask • 172.16.0.0/22 is assigned to this network • Refer to chapter 6, p51 on Using VLSM

40. Variable Length Subnet Mask (cont’d) • Require 9 host bits to support the largest number of hosts • mask is /23 prefix • 1 bit is used for subnet to create 2 subnets • 172.16.0.0/23 (subnet 0) • 172.16.2.0/23 (subnet 1) • Assign 172.16.0.0/23 (subnet 0) to Student LAN • Instructor LAN has the next fewer hosts, i.e. 69 hosts • require 7 host bits to accommodate 69 hosts • Use 172.16.2.0/23 to create 4 more subnets • 172.16.2.0/25 (subnet 0) • 172.16.2.128/25 (subnet 1) • 172.16.3.0 /25 (subnet 2) • 172.16.3.128/25 (subnet 3)

41. Calculating Addresses Case Study 2

42. Network Topology

43. VLSM • Keep 5 host bits to accommodate the largest number of hosts • 25 – 2 = 30 usable host addresses • 3 bits are used to create 8 subnets (23 – 2) • Network B will use 192.168.1.0/27 (subnet 0) • valid range of host addresses is 192.168.1.1 to 192.168.1.30 • Network E will use 192.168.1.32/27 (subnet 1) • valid range of host addresses is 192.168.1.33 to 192.168.1.62 • Network A will use 192.168.1.64/28 (subnet 0 in subnet 2) • valid range of host addresses is 192.168.1.65 to 192.168.1.78 • Network D will use 192.168.1.80/28 (subnet 1 in subnet 2) • valid range of host addresses is 192.168.1.81 to 192.168.1.94 • Network C will use 192.168.1.96/30 (subnet 0 in subnet 3) • valid range of host addresses is 192.168.1.97 to 192.168.1.98

44. 128 64 32 16 8 4 2 1 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 2 0 1 0 0 0 0 0 0 0 1 0 1 0 0 0 0 3 0 1 1 0 0 0 0 0 Creating Subnets

45. Device Interfaces • LAN interfaces • used for connecting UTP cables that terminate LAN devices such as computers, switches and routers • AUI, Ethernet and FastEthernet • WAN interfaces • used for connecting WAN devices to CSU/DSU • serial and BRI • Console interface • provide configuration to the device • Auxiliary (AUX) interface • a modem is connected to the interface for remote management

46. Device Management Connection • A RJ-45 to DB-9 or RJ-45 to DB-25 adaptor is connected to the EIA/TIA-232 serial port of the PC • a rollover cable is used to connect the adapter to the device console • The PC runs a program called a terminal emulator • terminal emulator program, such as HyperTerminal, is used to access the functions of a networking device • COM port settings are 9600 bps, 8 data bits, no parity, 1 stop bit and no flow control • This provides out-of-band console access • AUX port may be used for a modem-connected console

47. Accessing the Device Console • Connect the RJ-45 to DB-9 adapter to the console port using a rollover cable • newer computers that do not have an EIA/TIA-232 serial interface will need a USB-to-serial adapter • The HyperTerminal program can be accessed via Start  All Programs  Accessories  Communications • select the serial COM port and configure the port settings as shown • Power on the device and the boot-up sequence will be displayed in the HyperTerminal window