Bài giảng Mạng máy tính nâng cao - Chương 2: Wan and Router

Mạng Máy Tính Nâng CaoChương 2:WAN AND ROUTERObjectiveIdentify organizations responsible for WAN standards Explain the difference between a WAN and LAN and the type of addresses each uses Describe the role of a router in a WAN Identify internal components of the router and describe their functions Describe the physical characteristics of the router Identify common ports on a router Properly connect Ethernet, serial WAN, and console ports ObjectiveDescribe the purpose of the IOS Describe the basic operation of the IOS Identify various IOS features Identify the methods to establish a command-line interface (CLI) session with the router Move between the user command executive (user EXEC) and privileged EXEC modes Establish a HyperTerminal session on a router Log into a router Use the help feature in the command line interface WAN STANDARDS -WAN Devices WAN Devices Routers offer many services, including internetworking and WAN interface ports. Switches in the WAN provide connectivity for voice, data, and video communication. Modems include interface voice-grade services, channel service units/digital service units (CSU/DSUs) that interface T1/E1 services, and Terminal Adapters/Network Termination 1 (TA/NT1s) that interface Integrated Services Digital Network (ISDN) services. Communication servers concentrate dial-in and dial-out user communication. 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 are defined and managed by a number of recognized authorities, including the following agencies: International Telecommunication Union-Telecommunication Standardization Sector (ITU-T), formerly the Consultative Committee for International Telegraph and Telephone (CCITT) International Organization for Standardization (ISO) Internet Engineering Task Force (IETF) Electronic Industries Association (EIA) WAN physical layer protocols WAN data link protocols WAN data link protocols High-Level Data Link Control (HDLC) -- an IEEE standard; may not be compatible with different vendors because of the way each vendor has chosen to implement it. HDLC supports both point-to-point and multipoint configurations with minimal overhead  Frame Relay -- uses high-quality digital facilities; uses simplified framing with no error correction mechanisms, which means it can send Layer 2 information much more rapidly than other WAN protocols Point-to-Point Protocol (PPP) -- described by RFC 1661; two standards developed by the IETF; contains a protocol field to identify the network layer protocol WAN data link protocols Link Access Procedure Balanced (LAPB) data link protocol used by X.25; has extensive error checking capabilities Link Access Procedure D-channel (LAPD) the WAN data link protocol used for signaling and call setup on an ISDN D-channel. Data transmissions take place on the ISDN B channels Link Access Procedure Frame (LAPF) for Frame-Mode Bearer Services; a WAN data link protocol, similar to LAPD, used with frame relay technologies WAN Technologies Most common WAN technologies grouped into :Circuit-Switched Services Packet-Switched Services Cell-Switched Services Dedicated Digital Services Analog services Circuit-Switched Services POTS (Plain Old Telephone Service) -- not a computer data service, but included for two reasons: (1) many of its technologies are part of the growing data infrastructure, (2) it is a model of an incredibly reliable, easy-to-use, wide-area communications network; typical medium is twisted-pair copper wireNarrowband ISDN (Integrated Services Digital Network) -- a versatile, widespread, historically important technology; was the first all-digital dial-up service; usage varies greatly from country to country; cost is moderate; maximum bandwidth is 128 kbps for the lower cost BRI (Basic Rate Interface) and about 3 Mbps for the PRI (Primary Rate Interface); usage is fairly widespread, though it varies considerably from country to country; typical medium is twisted-pair copper wire Packet-Switched Services X.25 -- an older technology, but still widely used; has extensive error-checking capabilities from the days when WAN links were more prone to errors, which make it reliable but limits its bandwidth; bandwidth may be as high as 2 Mbps; Frame Relay -- a packet-switched version of Narrowband ISDN; has become an extremely popular WAN technology in its own right; more efficient than X.25, but with similar services; maximum bandwidth is 44.736 Mbps; 56kbps and 384kbps are extremely popular in the U.S.; usage is widespread; cost is moderate to low; Typical media include twisted-pair copper wire and optical fiber Cell-Switched Services ATM (Asynchronous Transfer Mode) -- closely related to broadband ISDN; becoming an increasingly important WAN (and even LAN) technology; uses small, fixed length (53 byte) frames to carry data; maximum bandwidth is currently 622 Mbps, though higher speeds are being developed; typical media are twisted-pair copper wire and optical fiber; usage is widespread and increasing; cost is highSMDS (Switched Multimegabit Data Service) -- closely related to ATM, and typically used in MANs; maximum bandwidth is 44.736 Mbps; typical media are twisted-pair copper wire and optical fiber; usage not very widespread; cost is relatively high Dedicated Digital Services T1, T3, E1, E3 -- the T series of services in the U.S. and the E series of services in Europe are extremely important WAN technologies T1 -- 1.544 Mbps T3 -- 44.736 Mbps E1 -- 2.048 Mbps E3 -- 34.368 Mbps xDSL (DSL for Digital Subscriber Line and x for a family of technologies) HDSL -- high-bit-rate DSL SDSL -- single-line DSL ADSL -- asymmetric DSL VDSL -- very-high-bit-rate DSL RADSL -- rate adaptive DSL Dedicated Digital ServicesSONET (Synchronous Optical Network) -- a family of very high-speed physical layer technologies; designed for optical fiber, but can also run on copper cables implemented at different OC (optical carrier) levels ranging from 51.84 Mbps (OC-1) to 9,952 Mbps (OC-192) Analog services Dial-up modems (switched analog)Cable modems (shared analog) Wireless WAN Technology-CompleteViewMạng Máy Tính Nâng CaoROUTER BASICS Routers are Computers Routers are at the network centerA router connects multiple networks. This means that it has multiple interfaces that each belong to a different IP network. Each network that a router connects to typically requires a separate interface. These interfaces are used to connect a combination of both Local Area Networks (LANs) and Wide Area Networks (WANs).Routers are Computers Routers determine the best path: The primary responsibility of a router is to direct packets destined for local and remote networks by:Determining the best path to send packets Forwarding packets toward their destinationEvolution of Routers Multiprotocol devices providing pure data delivery with minimal access control and QoS.Intelligent Network Services, this allowed us to provide security capabilities like integrated firewall and encryption.Integrated voice and data capabilities, allowing routers to provide voice gateway features for IP telephony.Today the router is an integrated platform for providing advanced services in security, content delivery, and voice.Cisco Router Series Router Components Router Internal Components Router Internal Components Router Internal Components Router Internal Components CPU-Executes operating system instructionsRandom access memory (RAM)-Contains the running copy of configuration file. Stores routing table. RAM contents lost when power is offRead-only memory (ROM)-Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program.Non-volatile RAM (NVRAM)-Stores startup configuration. This may include IP addresses (Routing protocol, Hostname of router)Router Internal Components Flash memory-Contains the operating system (Cisco IOS)Interfaces-There exist multiple physical interfaces that are used to connect network. Examples of interface types:Ethernet / FastEthernet interfacesSerial interfacesManagement interfacesRouter Internal Components Interfaces – The router connections to the outside. The three types of interfaces: Local-area network (LANs), Wide-area network (WANs), Console/AUX. The LAN interfaces are usually one of several different varieties of Ethernet or Token Ring. The LAN interfaces may be a fixed configuration or modular. The WAN interfaces include serial, ISDN. The WAN interfaces may be a fixed configuration or modular. The Console/AUX ports are serial ports used primarily for the initial configuration of the router. They are used for terminal sessions from the communication ports on the computer or through a modem. Router Internal ComponentsRouter Interface Router Interface is a physical connector that enables a router to send or receive packetsEach interface connects to a separate networkConsist of socket or jack found on the outside of a router Types of router interfaces:EthernetFastethernetSerialDSLISDNCable Router Interface Two major groups of Router InterfacesLAN InterfacesAre used to connect router to LAN networkHas a layer 2 MAC address Can be assigned a Layer 3 IP addressUsually consist of an RJ-45 jackWAN InterfacesAre used to connect routers to external networks that interconnect LANsDepending on the WAN technology, a layer 2 address may be usedUses a layer 3 IP address Router Interfaces Routers and the Network Layer The main purpose of a router is to connect multiple networks and forward packets destined either for its own networks or other networks. A router is considered a Layer 3 device because its primary forwarding decision is based on the information in the Layer 3 IP packet, specifically the destination IP address. This process is known as routing Routers and the Network Layer Routers Operate at Layers 1, 2 & 3Router receives a stream of encoded bitsBits are decoded and passed to layer 2Router de-encapsulates the frameRemaining packet passed up to layer 3Routing decision made at this layer by examining destination IP addressPacket is then re-encapsulated & sent out outbound interface Routers and the Network LayerConnecting console interfaces Connecting console interfaces To connect the PC to a router: Configure terminal emulation software (HyperTerminal) on the PC for: The appropriate com port9600 baud 8 data bits No parity 1 stop bit No flow controlConnect 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. Connecting auxiliary (AUX) port Connecting WAN interfaces Show more...ROUTER MODES Cisco IOS Similar to a PC, a router or switch cannot function without an operating system. The Cisco Internetwork Operating System (IOS) is the system software in Cisco devices. It is the core technology that extends across most of the Cisco product lineCisco IOS The Cisco IOS provides devices with the following network services: Basic routing and switching functions Reliable and secure access to networked resources Network scalabilityThe IOS operational details vary on different internetworking devices, depending on the device's purpose and feature set.The services provided by the Cisco IOS are generally accessed using a command line interface (CLI). The IOS file: several megabytes, is stored in a semi-permanent memory area called flash. Flash memory provides non-volatile storage.Using flash memory allows the IOS to be upgraded to newer versions or to have new features added. The IOS may be copied into RAM when the device is powered on and the IOS runs from RAM when the device is operating.Cisco IOS Access Methods Access Methods Console Telnet or SSH AUX portConsole Low speed serial connection to directly connect a computer or terminal to the console port on the router or switch. Provides access to a routerOften used to access a device when the networking services have not been started or have failed.Examples of console use are: The initial configuration of the network deviceDisaster recovery procedures and troubleshooting where remote access is not possiblePassword recovery proceduresThe device should be located in a locked room or equipment rack to prevent physical access.Telnet and SSH Telnet Require active networking services on the device. Run on layer 7 in OSI modelSecure Shell (SSH) protocolLike telnet but more secure accessStronger passwordUses encryption when transporting session dataUse can use ssh client on PC name: Putty As a best practice, always use SSH in place of Telnet whenever possible.AUX Another way to establish a CLI session remotely is via a telephone dialup connection using a modem connected to the router's AUX portCan used locally, like console portConsole port is also preferred over the auxiliary port for troubleshooting because it displays router startup, debugging, and error messages by default. Connecting console interfaces Establishing a HyperTerminal session Take the following steps to connect a terminal to the console port on the router: 1. Connect the terminal using the RJ-45 to RJ-45 rollover cable and an RJ-45 to DB-9 or RJ-45 to DB-25 adapter. 2. Configure the terminal or PC terminal emulation software for 9600 baud, 8 data bits, no parity, 1 stop bit, and no flow control. Configuration file Types of Configuration Files The running configuration file used during the current operation of the device Changes to the running configuration will immediately affect the operation of the Cisco deviceThe startup configuration file used as the backup configuration and is loaded when the device is started The startup configuration file or startup-config file is stored in non-volatile RAM (NVRAM)Router user interface modes For security purposes, the router has two levels of access to commands User EXEC mode --Typical tasks include those that check the router status. In this mode, router configuration changes are not allowed. Privileged EXEC mode --Typical tasks include those that change the router configuration. Router user interface modes Cisco IOS Modes Different modes and the mode prompts in the CLI Basic IOS Command Structure After entering each complete command, including any keywords and arguments, press the key to submit the command to the command interpreterUsing CLI Help Using “?”Using CLI Help Using CLI Help Using CLI Help Tab -Completes the remainder of the command or keywordCtrl-R -Redisplays a lineCtrl-Z -Exits configuration mode and returns to the EXECDown Arrow-Allows user to scroll forward through former commandsUp Arrow-Allows user to scroll backward through former commandsCtrl-Shift-6-Allows the user to interrupt an IOS process such as ping or tracerouteCtrl-C orCtrl-Z -Aborts the current command and exits the configuration modeEnhanced editing commands Router command history Set the command history buffer size Recall commands Disable the command history feature Examination Commands Examination Commands Examination Commands IOS Configuration modes IOS Configuration mode Interface mode-to configure one of the network interfaces (Fa0/0, S0/0/0,..)Line mode-to configure one of the lines (physical or virtual) (console, AUX, VTY,..) Router mode-to configure the parameters for one of the routing protocolsRemember, as configuration changes are made within an interface or process, the changes only affect that interface or process.Once a change has been made from the global mode, it is good practice to save it to the startup configuration file stored in NVRAM. Router#copy running-config startup-configGlobal Configuration Mode All command-line interface (CLI) configuration changes to a Cisco router are made from the global configuration mode. For Examples:Interface mode Line mode Router mode Subinterface mode Controller mode Router#configure terminalRouter(config)# exit : Returns the router to global configuration mode from one of these specific configuration modes Ctrl-Z : Returns the router to privileged EXEC mode Overview of Router Modes Mạng Máy Tính Nâng Cao Applying a Basic ConfigurationUsing Cisco IOS Naming a device Some guidelines for naming conventions are that names should:Start with a letterNot contain a spaceEnd with a letter or digitHave characters of only letters, digits, and dashesBe 63 characters or fewerNaming a device Two common approaches to establishing naming conventions: the location and the purpose To remove the name of a device, use: AtlantaHQ(config)# no hostname Router(config)# Configuring Passwords and Using Banners The passwords introduced here are:Console password-limits device access using the console connectionEnable password -limits access to the privileged EXEC modeEnable secret password -encrypted, limits access to the privileged EXEC modeVTY password -limits device access using TelnetConsole password VTY and Enable password Configuring router passwords Using Banners Configuring message-of-the-day (MOTD) Enter global configuration mode by using the command configure terminal. Enter the command banner motd # The message of the day goes here #. Save changes by issuing the command copy running-config startup-config. Using Banners Configuring a serial interface Interface Configuration Commands Serial Interface Configuration Example Configuring an Ethernet interface Configuring interface description Configuring interface description Enter global configuration mode by entering the command configure terminal. Enter specific interface mode (for example interface Ethernet 0) interface ethernet 0. Enter the command description followed by the information that is to be displayed. For example, XYZ Network, Building 18. Exit interface mode back to privileged EXEC mode by using the command ctrl-Z. Save the configuration changes to NVRAM by using the command copy running-config startup-config. Configuring interface description Host name resolution To associate a host name with an IP address. A list of host names and their associated IP addresses is called a host table. Host names, unlike DNS names, are significant only on the router on which they are configured. Configuring host tables Enter global configuration mode in the router. Enter the command ip host followed by the name of the router and all IP addresses associated with the interfaces on each router. Continue entering until all routers in the network are entered. Save the configuration to NVRAM. Managing configuration files After making changes to a configuration, consider these options for the next step: Make the changed configuration the new startup configuration.Return the device to its original configuration.Remove all configuration from the deviceBackup Configuration on TFTP Server Backup Configuration on TFTP ServerEnter the copy running-config tftp command.Enter the IP address of the host where the configuration file will be stored.Enter the name to assign to the configuration file.Answer yes to confirm each choice.Removing All Configurationserase startup-configreload routerRestore Configuration from a TFTP Backup Configurations with Text Capture Backup Configurations with Text Capture Restoring Text Configurations When using HyperTerminal, the steps are: Locate the file to be copied into the device and open the text document. Copy all of the text. On the Edit menu, click paste to host.When using TeraTerm, the steps are: On the File menu, click Send file. Locate the file to be copied into the device and click Open. TeraTerm will paste the file into the device Executing adds, moves, and changes Working with release 11.x Examining the show commands show interfaces – Displays all the statistics for all the interfaces on the router. For example: Router#show interfaces serial 0/1show controllers serial – Displays information-specific to the interface hardware show version – Displays information about the router and the IOS that is running in RAM show protocol – Displays the global and interface specific status of any configured Layer 3 protocols show startup-config – Displays the saved configuration located in NVRAM show running-config – Displays the configuration currently running in RAM Examining the show commands show clock – Shows the time set in the router show hosts – Displays a cached list of host names and addresses show users – Displays all users who are connected to the router show history – Displays a history of commands that have been entered show flash – Displays information about flash memory and what IOS files are stored there show ARP – Displays the ARP table of the router