1. Cisco 2 - Router Perrine. J Page 111/12/2015 Chapter 1 WAN is a data communications network that operates beyond a LAN’s geographic scope. One must subscribe to a WAN provider such as AT&T, Sprint, RBOC. They provide network services such as: Frame Relay Integrated Services Digital Network (ISDN) Asynchronous Transfer Mode (ATM) Which carries traffic type of voice, data and video. In general, WAN’s operate at the 1st three layers of the OSI. (Though Frame Relay actually operates at layer 1 and layer 2.) So all of the WAN services have layer 1 & layer 2 in common. Other characteristics of WAN are: operate beyond LAN geographic area use serial connections provide full-time & part-time connectivity

2. Cisco 2 - Router Perrine. J Page 211/12/2015 Chapter 1 Router’s Internal Components The main internal components of the router are: Random Access Memory (RAM) Nonvolatile Random-Access Memory (NVRAM) flash memory Read-Only Memory (ROM) Interfaces

3. Cisco 2 - Router Perrine. J Page 311/12/2015 Chapter 1 Router’s Internal Components RAM: stores routing tables holds ARP cache holds 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

4. Cisco 2 - Router Perrine. J Page 411/12/2015 Chapter 1 Router’s Internal Components NVRAM: provides storage for the startup configuration file retains content when router is powered down or restarted

5. Cisco 2 - Router Perrine. J Page 511/12/2015 Chapter 1 Router’s Internal Components Flash memory: holds the operating system image (IOS) allows software to be updated without removing & replacing chips on the processor retains content when router is powered down or restarted can store multiple versions of IOS software is electronically erasable, programmable ROM (EEPROM)

6. Cisco 2 - Router Perrine. J Page 611/12/2015 Chapter 1 Router’s Internal Components ROM: maintains instructions for power-on self test (POST) diagnostics stores bootstrap program & basic operating system software requires replacing pluggable chips on the motherboard for software upgrades

7. Cisco 2 - Router Perrine. J Page 711/12/2015 Chapter 1 Router’s Internal Components Interfaces: connect router to network for frame entry & exit can be on the motherboard or on a separate module connect the router to LANs and WANs

8. Cisco 2 - Router Perrine. J Page 811/12/2015 Chapter 1 Subscriber to Provider Interface DTE DCE Router Modem A key interface in the customer site occurs between the Data Terminal Equipment (DTE) such as a router to the Data Circuit-Terminating equipment (DCE) to the WAN network such as a modem. DTE is on the customer’s side of the network. The DCE is a modem and in many cases is circuitry in a CO, switch which is made up of a CSU/DSU (Channel Service Unit/Data Service Unit). The major reason for CSU/DSU is to protect the equipment from CPE/DTE from aberrant voltages, and to ‘square’ up the signal. DCE is usually on the provider’s side.

9. Cisco 2 - Router Perrine. J Page 911/12/2015 Chapter 1 Subscriber to Provider Interface DTE DCE Router Modem EIA/TIA-232, V.35, X.21, HSSI, others

10. Cisco 2 - Router Perrine. J Page 1011/12/2015 Chapter 1 Routers Physical Characteristics The 3 basic types of connections on a router are: 1.LAN interfaces 2.WAN interfaces 3.Management ports Console auxiliary

11. Cisco 2 - Router Perrine. J Page 1111/12/2015 Chapter 1 Routers Physical Characteristics Management ports provide Text-based connection Configuration, monitoring, password recovery and troubleshooting The management ports: EIA-232 asynchronous serial ports used for non-network connections used for initial router configuration to connect to a port, a PC must have a terminal emulation program rollover cable from PC to the management ports

12. Cisco 2 - Router Perrine. J Page 1211/12/2015 Chapter 1 Management Ports The console port, says Cisco is preferred when troubleshooting: doesn’t depend on network services displays start and error messages by default To establish a connection between PC and a router, one needs terminal emulation software rollover cable RJ-45 to DB-9 connector

13. Cisco 2 - Router Perrine. J Page 1311/12/2015 Chapter 1 Routers Physical Characteristics Cisco says, the terminal emulation software, HyperTerminal, the parameters used to configure a router are: Data bits Stop bits parity

14. Cisco 2 - Router Perrine. J Page 1411/12/2015 Chapter 1 Router’s connection LAN & WAN For a PC of a LAN to connect to a router, one straight-thru cable from the PC to a HUB or switch straight-thru cable from the HUB or switch to router’s Ethernet interface

15. Cisco 2 - Router Perrine. J Page 1511/12/2015 Chapter 1 Router’s connection LAN & WAN An internetwork must include: switching dynamic or static routing consistent end-to-end addressing

16. Cisco 2 - Router Perrine. J Page 1611/12/2015 Chapter 1 Router’s connection to LAN & WAN DTE DCE Router Modem EIA/TIA-232, V.35, X.21, HSSI, others The connections to WAN on router is through the serial interface, either as a Smart Serial interface connector or DB-60 connector. The following devices are used in the construction of a WAN: communication servers routers modems

17. Cisco 2 - Router Perrine. J Page 1711/12/2015 Chapter 1 Router vs. PC Cisco says the common components between a router and PC are: CPU input/output interfaces system bus