Networking Basics CCNA 1 Chapter 5

1. Networking Basics CCNA 1Chapter 5

2. Cabling LANs Line Styles for Cables Used in Network Diagrams

3. Cabling LANs Ethernet LAN Physical Layer • Earliest Ethernet standards used coaxial cabling • Today’s standards called for twisted-pair (usually UTP) or fiber-optic cabling • IEEE separated Ethernet into two standards • IEEE 802.2 - Logical Link Control (LLC) sublayer defines part of the OSI data link layer • IEEE 802.3 – Media Access Control (MAC) sublayer also defines part of the OSI data link layer

4. Cabling LANs Ethernet LAN Physical Layer (continued)

5. Cabling LANs Ethernet LAN Physical Layer Design Considerations • Does maximum cable length allowed meet segment requirements • Cost of cable • Cost of equipment on ends of cable • Which cables support which Ethernet speeds • Ease of installation • Susceptibility to interference

6. Cabling LANs Choosing Ethernet Types (Speeds) in the Campus • Network engineers must consider speed of Ethernet types • Most current PCs have 10/100 Mbps NICs – means a current design would use 100 Mbps Ethernet on the LAN • Most new PCs come with 10/100/1000 Mbps NICs – must consider expense of upgrading LAN switches to 1000 Mbps (1 Gbps)

7. Cabling LANs Three Types of Ethernet Links • End-user level – Links between a hub/switch and end users’ computers • Workgroup level – Links between the hub/switch that attach to end users’ computers and other hubs/switches in the LAN core • Backbone level – Links between the hubs/switches in the LAN core

8. Cabling LANs Campus LAN with Online Curriculum’s LAN Level Terms

9. Cabling LANs Ethernet Types and Speeds Used on Various Link Types per Online Curriculum

10. Cabling LANs Ethernet Types and Speeds Used on Various Link Types – Best Practices • End-user level: 100 Mbps • Workgroup level: 1 Gbps • LAN Core (Backbone): 1 Gbps or 10 Gbps • Remember, speeds will increase as the technology evolves

11. Cabling LANs Components of the Campus Design Model • Access switches and links – end-user devices connect to access switches (LAN switches), with Ethernet links called access links • Distribution switches and uplinks – a large number of access switches connect to a smaller number of distribution switches; the links between them are called uplinks

12. Cabling LANs Components of the Campus Design Model (continued) • Building block – a single building’s design with access and distribution switches • Core switches and links – in large campuses, each building block is connected to very fast core switches, using core links

13. Cabling LANs Ethernet Types, Media and Segment Lengths

14. Cabling LANs Ethernet Types, Media and Segment Lengths (continued)

15. Cabling LANs Ethernet Types, Media and Segment Lengths • Using the charts is important to the LAN planning process • Most paths between devices are not straight line • After media are selected, cables with appropriate connectors must be ordered or made • Some older NICs and networking devices use attachment user interface (AUI) connectors

16. Cabling LANs Common LAN Cable Connectors

17. Cabling LANs Picking UTP Cable Pinouts • Straight-through – use TIA/EIA-T568-A or TIA/EIA-T568-B on both ends • Crossover (10BASE-T and 100BASE-TX) - use TIA/EIA-T568-A on one end and TIA/EIA-T568-B on the other end • Crossover (1000BASE-TX) – use TIA/EIA-T568-A on one end and swap the orange/green (pairs 1 and 2) and blue/brown pairs (pairs 3 and 4) on the other end

18. Cabling LANs TIA/EIA-T568-A and TIA/EIA-T568B Pinouts

19. Cabling LANs 10BASE-T and 100BASE-TX Crossover Cable

20. Cabling LANs 1000BASE-T Crossover Cable

21. Cabling LANs Crossover Cables • Many products, including Cisco switches, us Auto Medium-independent Crossover (Auto-mdix) • Detects when a cable with wrong pinouts is connected • Automatically makes internal changes to make connection work

22. Cabling LANs Choosing When to Use Straight-Through and Crossover Cables • Devices that transmit at pins 1 and 2: PCs, routers, servers, wireless access points’ Ethernet ports • Devices that transmit at pins 3 and 6: hubs, switches, bridges, repeaters

23. Cabling LANs Choosing When to Use Straight-Through and Crossover Cables • Use a straight-through cable to connect • Switch to router • Switch to PC or server • Hub to PC or server

24. Cabling LANs Choosing When to Use Straight-Through and Crossover Cables • Use a crossover cable to connect • Switch to switch • Switch to hub • Hub to hub • Router to router • PC to PC • Router to PC

25. Cabling LANs Choosing When to Use Straight-Through and Crossover Cables • Cisco prints an “X” on ports that transmit on pins 3 and 6 instead of pins 1 and 2 • This denotes they are internally crossed over

26. Cabling LANs Choosing When to Use Straight-Through and Crossover Cables

27. Cabling LANs Connecting Ethernet Networking Devices • Must play close attention to distances between devices • Must consider how extending the length of the network by adding devices has an impact

28. Cabling LANs Connecting Ethernet Networking Devices • Repeaters • Extend the distances over which an Ethernet network can send data • Receives a degraded signal, cleans it up and retimes it, and sends it out the other port • Cannot indefinitely extend a LAN

29. Cabling LANs Connecting Ethernet Networking Devices • Repeaters • 5-4-3 rule • At most 5 cables in the LAN • At most 4 repeaters • At most 3 cables can have PCs attached • Allows for maximum distance of 500 meters

30. Cabling LANs Basic Function of a Repeater

31. Cabling LANs Connecting Ethernet Networking Devices • Hubs • IEEE created 10BASE-T and hubs to overcome problems with older Ethernet standards • Old standard called for a physical bus topology • New standard allows a physical star topology • Thinner cable makes installation easier • Maximum single cable length of 100 m, versus 185 m and 500 m

32. Cabling LANs Connecting Ethernet Networking Devices • Hubs (continued) • 10BASE-T allows the use of hubs and repeaters • Similar to repeaters, hubs receive a signal on one port, regenerate it, and send it out all other ports • Hubs contain multiple RJ-45 jacks to provide a place to connect multiple UTP cables, which creates the physical star topology • Hubs are sometimes called “multiport repeaters” or “concentrators”

33. Cabling LANs 10BASE-T with Hub Operation

34. Cabling LANs Comparing the Three Types of Ethernet Hubs

35. Cabling LANs Connecting Ethernet Networking Devices • Bridges • Use logic to decide whether to forward frames • This logic is closely matched to OSI Layer 2, so bridges are considered to be Layer 2 devices • Bridges use this process: • Examine incoming frame, look at destination MAC address • If destination MAC is reachable via a different interface than the one one which it was received, regenerate and forward out that interface (forward) • If destination MAC is on the same interface it arrived on, discard the frame (filter)

36. Cabling LANs Bridge Making a Filtering Decision

37. Cabling LANs Bridge Making a Forwarding Decision

38. Cabling LANs Connecting Ethernet Networking Devices • Ethernet switches • Provide all the benefits of repeaters, hubs and bridges • Most LANs use switches instead of hubs or bridges • LANs need repeaters only when very long runs are needed

39. Cabling LANs Connecting Ethernet Networking Devices • Functions of an Ethernet Switch • Like a hub, provides a large number of ports for making a physical star topology • Like repeaters, hubs and bridges, regenerates a clean signal • Like bridges, uses filtering/forwarding logic • Like bridges, separates a LAN into multiple collision domains, increasing LAN bandwidth • Beyond the functions of hubs, repeaters, and bridges, offers advanced features such as virtual LANS (VLANs) and much faster performance

40. Cabling LANs Switch Making a Forwarding Decision

41. Cabling LANs Connecting Ethernet Networking Devices • Functions of an Ethernet Switch (continued) • Uses a switching table much the same way a bridge uses a bridging table - Cisco switching table is sometimes referred to as Content Addressable Memory (CAM) table • Allows devices to send data at the same time without collisions by using full-duplex logic

42. Cabling LANs Switch with Four 100 Mbps Ports – 400 Mbps

43. Cabling LANs Wireless Communications and Wireless Access Points • “Wireless” does not mean just WLANs or Wi-Fi • Includes most every type of electromagnetic (EM) energy • Radio waves • Microwaves • Infrared light

44. Cabling LANs Wireless Communications and Wireless Access Points • Infrared (IR) and radio frequencies (RF) are both popular for wireless communication today • IR requires line-of-sight between sending and receiving devices (TV remote control and TV)

45. Cabling LANs Wireless Communications and Wireless Access Points • RF has been used for communications for more than a century: AM/FM radio, Airplane to control tower, Police and fire departments • Does not require line-of-sight • Wireless devices designed for two-way communication need a transmitter and a receiver • WLAN standards use a range of frequencies called a spread spectrum

46. Cabling LANs WLAN Review • Wireless Access Points (APs) • Have much in common with hubs and switches • Provide a centralized connection point (without wires) • Have limitations on distance • Like hubs, create a shared medium • PCs and laptops use wireless cards, so no networking cables are needed • The AP connects to the rest of the network with a cable

47. Cabling LANs AP, Switch, and Hub Used for End-User Device Access

48. Cabling LANs Ethernet NICs • NICs – expansion PC cards that create a way for the PC to connect to a network • Must operate and OSI Layers 1 and 2 • Layer 1 – send and receive signals over an attached cable • Layer 2 – they frame data inside a header and trailer, with header including Layer 2 address called the Media Access Control (MAC) address

49. Cabling LANs Ethernet NICs • Network diagrams do not usually show the NIC as it is assumed each PC has one • On laptops, the NIC might be built in or in a small expansion slot called a PC card slot

50. Cabling LANs Ethernet NIC: Circuit Board Internal to the PC