Giáo trình CCNA - Chương 2

CCNA – Semester2 Module 1 WANs and Routers Objectives • WANs characteristics • Describe the role of a router in a WAN • Router components • Router connections WANs Introduction to WANs • These are the major characteristics of WANs: – They connect devices that are separated by wide geographical areas. – They use the services of carriers – They use serial connections of various types to access bandwidth over large geographic areas. WANs characteristics • A WAN operates at the physical layer and the data link layer of the OSI reference model. • It interconnects LANs that are usually separated by large geographic areas. • WANs provide for the exchange of data packets and frames between routers and switches and the LANs they support. WAN Devices WAN Standards • WAN physical layer protocols describe how to provide electrical, mechanical, operational, and functional connections for WAN services • WAN data link protocols describe how frames are carried between systems on a single data link. WAN standards and OSI model Physical Layer Data Link Layer OSI model WAN Specifications SMDS X21 bis EIA/TIA-232 EIA/TIA-449 V24 V35 HSSI G.703 EIA-530 LAPB Frame Relay X25 PLP HDLC PPP SDLC MAC sublayer LLC sublayer Network Layer WAN: Physical Layer standards • Describes the interface between the DTE and the DCE • EIA/TIA-232, V.24 (DB25) • EIA/TIA-449 (DB37) • EIA-530 (DB25) • V.35 (DB34) • X.21 (DB15) • G.703 (BNC) www.connectworld.net WAN Standards: Protocols Typical WAN Layer 2 Links Circuit-switched PPP, SLIP, HDLC Telephone Company Packet-switched X.25, Frame Relay, ATM Service Provider Leased Line HDLC, PPP, SLIP WAN: Data Link Layer standards • HDLC í High-Level Data Link Control í IEEE standard from SDLC í Point-to-point and multipoint links í Operates over sync. links • LAPB í Link Access Procedure Balanced í used by X.25 protocol • LAPD í Link Access Procedure D-channel í ISDN D-Channel for control signal • LAPF í Link Access Procedure Balanced í Used in Frame Relay for fast frame switching over high-quality digital facilities • SLIP í Serial Line Interface Protocol í Designed to carry IP packets í Being replaced by PPP • PPP í Point-to-Point Protocol í Support multiple network layer protocols (IP, IPX, DecNET) í Operates over sync. or async. links • SDLC í Synchronous Data Link Control Protocol í IBM designed protocol í Point-to-point & multipoint links í Operates over sync. links A typical WAN setup Point-to-point or circuit-switched connection CO Switch Customer Premises Equipment Demarcation Local Loop WAN service provider toll network Trunks and switches S S S SS S S Internetwork with router • Consistent end-to-end addressing • Addresses that represent network topologies • Best path selection • Dynamic or static routing • Switching Academy approach to hands-on labs • In the academy lab, devices that make up the WAN cloud are simulated by the connection between the back-to-back DTE-DCE cables. Routers Introduction to routers in a WAN • A router is a special type of computer. It has a CPU, memory, a system bus, and various input/output interfaces. • Routers need the Internetwork Operating System software (IOS) to run configuration files. • Configuration files contain the instructions and parameters that control the flow of traffic in and out of the routers. Router Component: CPU • The Central Processing Unit (CPU) executes instructions in the operating system. Among these functions are system initialization, routing functions, and network interface control. • The CPU is a microprocessor. Large routers may have multiple CPUs. Router Component: RAM • RAM, also called dynamic RAM (DRAM), has the following functions: –Stores routing tables –Holds ARP cache –Holds fast-switching cache – Performs packet buffering (shared RAM) –Providestemporary memory for the configuration file of the router while the router is powered on – Loses content when router is powered down or restarted Router Component: RAM • RAM provides run time space for executable Cisco IOS software and its subsystems. • RAM is usually logically divided into main processor memory and shared input/output (I/O) memory. • RAM can be upgraded by adding additional Dual In-Line Memory Modules (DIMMs). [...]... compliant 1 Ethernet/IEEE 8 02. 3 interface(s) 2 Serial network interface(s) 32K bytes of non-volatile configuration memory 8192K bytes of processor board System flash (Read ONLY) Configuration register is 0x21 02 Command: show flash System flash directory: File Length Name/status 1 5895768 c1700-ny-mz. 12 2- 1 3.T8.bin [58958 32 bytes used, 24 927 76 available, 8388608 total] 8192K bytes of processor board... Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWARE (fc1) LAB_A uptime is 0 minutes System restarted by reload System image file is "flash:c1700-ny-mz. 12 2- 1 3.T8.bin", booted via flash cisco 25 00 (68030) processor (revision N) with 6144K /20 48K bytes of memory Processor board ID 0 921 8746, with hardware revision 00000000 Bridging software X .25 software, Version 2. 0, NET2, BFE and GOSIP compliant... supply may be external to the router 26 00 External Connection Management Ports • Provides a text-based connection for the configuration, monitoring and troubleshooting of the router • The common management interfaces are the console and auxilliary ports These are EIA -2 3 2 asynchronous serial ports • Computer must run a terminal emulation program to provide a text-based session with the router Management... settings • Connect the RJ-45 connector of the rollover cable to the router console port • Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter • Attach the female DB-9 adapter to a PC Summary • • • • • • WANs characteristics WANs standards and protocols Router internal components Router functions Router management ports Router LAN and WAN connection Module 2 Introduction to Router... Layer 3 protocols • show startup-configuration – Displays the saved configuration located in NVRAM • show running-configuration – Displays the configuration currently running in RAM Back to default configuration • Running configuration file can never be erased but you can bring router to default configuration erasing startup-config file and restart router: – erase startup-config – reload – Save configurations... that can be used as an alternative boot source • Requires replacing pluggable chips on the motherboard for software upgrades Router Component: Interfaces • Three types of interfaces are local-area network (LANs), wide-area network (WANs), and Console/AUX • Connect router to network for frame entry and exit, or connect to terminal for configuration • Can be on the motherboard or on a separate module (fixed... command history feature, the following tasks may be completed: – Set the command history buffer size – Recall commands – Disable the command history feature • terminal history size or the history size { 0 -2 56} : change the number of command lines the system records during a terminal session (default is 10) Summary • • • • • Purpose and operation of IOS IOS naming convention CLI: use EXEC and privileged... Interfaces status • Router interfaces have 2 status indications: interface (up/down) and line protocol (up/down), the links only work if both are up • By default, router interfaces are shutdown and the status is: interface is administratively down, line protocol is down Configuring serial link • One side must be considered a DCE and provide a clocking signal Router(config-if)#clock rate •... and Buffers Interfaces Active Programs Configuration File Backup Operating Configuration Systems File Router#show mem Router#show stacks Router#show buffers Router#show running-config Or Router#write term Router#show startup-config Or Router#show config Examining the show Commands • There are many show commands that you can use to examine the contents of files in the router and for troubleshooting... multiple versions of IOS software • Is a type of electronically erasable, programmable ROM (EEPROM) • Adding or replacing the flash Single In-Line Memory Modules (SIMMs) or PCMCIA cards can upgrade the amount of flash Router Component: ROM • Maintains instructions for power-on self test (POST) diagnostics • Stores bootstrap program and basic operating system software, load Cisco IOS software from Flash ro . CCNA – Semester2 Module 1 WANs and Routers Objectives • WANs characteristics • Describe the role of