Networking 2

• Wide-area network (WAN)


  A data communications network spanning a large geographic area such as a state, province, or country
• WAN


  • They use the services of carriers
  • Operates at the physical layer and the data link layer of the OSI reference model
  • Interconnects LANs that are usually separated by large geographic areas
• WAN data link protocols

  Describe how frames are carried between systems on a single data link
• WAN data link protocols

  • Protocols designed to operate over dedicated point-to-point, multipoint, and multi-access switched services such as Frame Relay
• Router


  Connects and allow communication between two networks and determine the best path for data to travel through the connected networks
• Router


  • Needs the Internetwork Operating System software (IOS) to run configuration files
  • Main internal components are random access memory (RAM), nonvolatile random-access memory (NVRAM), flash memory, read-only memory (ROM), and interfaces
• RAM


  Stores routing tables, holds ARP cache and fast-switching cache, performs packet buffering, maintains packet-hold queues, provides temporary memory for the configuration file of the router while the router is powered on, loses content when router is powered down or restarted
• NVRAM


  Provides storage for the startup configuration file, retains content when router is powered down or restarted
• Flash Memory


  Holds the operating system image (IOS), allows software to be updated without removing and replacing chips on the processor, retains content when router is powered down or restarted, can store multiple versions of IOS software, is a type of electronically erasable, programmable ROM (EEPROM)
• ROM


  Maintains instruction for power-on self test (POST) diagnostics, stores bootstrap program and basic operating system software, requires replacing pluggable chips on the motherboard for software upgrades
• Interfaces


  Connect router to network for frame entry and exit, can be on the motherboard or on a separate module
• Router LANs and WANs


  • While a router can be used to segment LANs, its major use is as a WAN device
  • Routers have both LAN and WAN interfaces
  • WAN technologies are frequently used to connect routers and these routers communicate with each other by WAN connections
• Routers are the backbone devices of large intranets and of the Internet
• Router functions


  • Selection of best path and the switching of frames to the proper interface
  • Routers accomplish this by building routing tables and exchanging network information with other routers
• WAN physical layer standards and protocols

  • EIA/TIA-232
  • EIA/TIA-449
  • V.24
  • V.35
  • X.21
  • G.703
  • EIA-530
  • ISDN
  • T1, T3, E1, and E3
  • xDSL
  • SONET
• WAN data link layer standards and protocols

  • High-level data link control (HDLC)
  • Frame Relay
  • Point-to-Point Protocol (PPP)
  • Synchronous Data Link Control (SDLC)
  • Serial Line Internet Protocol (SLIP)
  • X.25
  • ATM
  • LAPB
  • LAPD
  • LAPF
• Configure terminal emulation software on the PC for the following: the appropriate com port, 9600 baud, 8 data bits, 1 stop bit, No parity, No flow control
• Connecting Console Interfaces


  1. Connect a rollover cable to the router console port (RJ-45 connector)

  2. Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter

  3. Attach the female DB-9 adapter to a PC
• Connecting Router LAN Interfaces


  • A router is usually connected to a LAN through an Ethernet or Fast Ethernet interface
  • The router is a host that communicates with the LAN through a hub or a switch
  • A straight-through cable is used to make this connection
  • A 10BASE-TX or 100BASE-TX router interface requires Category 5, or better, unshielded twisted-pair (UTP) cable, regardless of the router type
• Router Serial WAN Connectors
• DCE Serial Connections