Institute of Technology Sligo - Dept of Computing WANs and Router Basics Semester 2 Chapter 2: WANs & Routers Chapter 3: Router CLI Paul Flynn

Institute of Technology Sligo - Dept of Computing Table of Contents  WAN Devices  WAN Standards  WAN Technologies  Router Basics  Router User Interface

Institute of Technology Sligo - Dept of Computing WAN Devices

Institute of Technology Sligo - Dept of Computing WAN Services  WANs provide for the exchange of data packets/frames between routers/bridges and the LANs they support.  A WAN interconnects LANs that are usually separated by large geographic areas.  WANs connect devices. Such devices include...

Institute of Technology Sligo - Dept of ComputingRouters  Routers offer many services including:  Internetworking  WAN serial interfaces  Routers can operate as...  Internal Routers  Backbone Routers  Area Border Routers  Autonomous System Boundary Routers

Institute of Technology Sligo - Dept of Computing WAN Bandwidth Switches  Service provider equipment that connects to WAN bandwidth for voice, data and video communications.

Institute of Technology Sligo - Dept of ComputingModems  Also called CSU/DSUs (channel service units/digital service units)  Interface with voice-grade connection in order to convert analog signal to digital.  Represents the DCE side of the DTE/DCE connection.  More on DTE/DCE later

Institute of Technology Sligo - Dept of Computing Communication Servers  Concentrates dial-in and dial-out services.  Equipment is usually at the service provider’s site.

Institute of Technology Sligo - Dept of Computing WAN Standards

Institute of Technology Sligo - Dept of Computing WAN Standards  What layers of the OSI model do WAN standards describe?  Physical and Data Link Layers

Institute of Technology Sligo - Dept of Computing WAN Physical Layer  Protocols that describe how to provide electrical, mechanical, operational, and functional connections for WAN services.  These services are most often obtained from WAN service providers such as RBOCs, alternate carriers, post-telephone, and telegraph (PTT) agencies.  Describes the interface between the data terminal equipment (DTE) and the data circuit- terminating equipment (DCE).

Institute of Technology Sligo - Dept of Computing WAN Physical Layer  Typically, the DCE is the service provider and the DTE is the attached device.  In this model, the services offered to the DTE are made available through a modem or a CSU/DSU.

Institute of Technology Sligo - Dept of Computing WAN Physical Layer  Several physical layer standards specifying this interface between the DTE & DCE are...  EIA/TIA-232  EIA/TIA-449  V.24  V.35  X.21  G.703  EIA-530

Institute of Technology Sligo - Dept of Computing WAN Data-Link Layer  WAN data link protocols describe how frames are carried between systems on a single data link.  They include protocols designed to operate over dedicated point-to-point, multipoint, and multi- access switched services.  WAN standards are defined and managed by a number of recognized authorities, including the following agencies: ITU-T, ISO, IETF, & EIA

Institute of Technology Sligo - Dept of Computing WAN Data-Link Encapsulations  High-Level Data Link Control (HDLC)  Cisco default encapsulation; typically used between routers running Cisco IOS; replacing SDLC  Streamlined: no windowing or flow control  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

Institute of Technology Sligo - Dept of Computing WAN Data-Link Encapsulations  Frame Relay  uses high-quality digital facilities;  uses simplified framing with no error correction mechanisms (connectionless!!);  it can send Layer 2 information much more rapidly than other WAN protocols

Institute of Technology Sligo - Dept of Computing WAN Data-Link Encapsulations  PPP (Point-to-Point Protocol)  Developed by IETF; replacing SLIP  Contains a field to identify the network layer protocol  PPP can check for link quality during connection establishment  Supports PAP (Password Authentication Protocol) & CHAP (Challenge Handshake Authentication Protocol)

Institute of Technology Sligo - Dept of Computing WAN Technologies

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing Dedicated Digital Services  T series in U.S. and E series in Europe  Uses time division multiplexing to “slice up” data and assign time slots for transmissions  T1 = Mbps  T3 = Mbps  E1 = Mbps  E3 = Mbps Uses twisted pair & fiber Extremely popular Moderate cost Dedicated Digital Services provide full-time connectivity through a point-to-point link

Institute of Technology Sligo - Dept of Computing Dedicated Digital Services  Digital Subscriber Lines (xDSL); the x stands for a family of technologies  New WAN Technology for home use; decreasing bandwidth with increasing distance from the phone companies CO.  Data rates as high as Mbps but more common to be in the 100s of Kbps  Varieties include HDSL, SDSL, ADSL, & VDSL  Moderate expense and getting cheaper

Institute of Technology Sligo - Dept of Computing Dedicated Digital Services  Synchronous Optical Network (SONET)  Specialized high bandwidth technology for use at various Optical Carrier speeds (OC) ranging from Mbps (OC-1) to 9,952 Mbps (OC-192)  Uses lasers to divide the wavelength of the light into sections that can carry large amounts of data (Wave Division Multiplexing)  Very expensive; used by large ISPs and other Internet backbone entities.

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing Analog Services  Dial-up Modems (switched analog)  Limited to 56 kbps  Works with existing phone network  Low cost and widespread usage

Institute of Technology Sligo - Dept of Computing Analog Services  Cable Modems (Shared Analog)  Puts data signals on the same cable as television signals  Increasing in popularity  Maximum bandwidth can be 10 Mbps, though this degrades as more users attach to a given network segment (behaving like an unswitched LAN)  Cost is relatively low; usage is small but increasing; the medium is coaxial cable.

Institute of Technology Sligo - Dept of Computing Analog Services  Terrestrial  Bandwidths typically in the 11 Mbps range  Cost is relatively low  Line-of-sight is usually required  Usage is moderate  Satellite  Can serve mobile users and remote users  Usage is widespread  Cost is very high Wireless

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing Circuit Switched Services  Plain Old Telephone System (POTS)  Not a computer data service but...  POTS is an important component of our communication infrastructure and  It is still the standard for designing reliable networks

Institute of Technology Sligo - Dept of Computing Circuit Switched Services  Integrated Services Digital Network (ISDN)  Historically important--first dial-up digital service  Cost is moderate; max. bandwidth = 128 kbps for BRI (Basic Rate Interface)  2 B 64kps and 1 D 16kps  B channels are voice/data channels; D for signaling B B D

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing Packet Switched Services  X.25 (Connection-oriented)  Older WAN technology developed in 1970s  Reliable--X.25 has been extensively debugged and is now very stable--literally no errors in modern X.25 networks  Store & Forward--Since X.25 stores the whole frame to error check it before forwarding it on to the destination, it has an inherent delay (unlike Frame Relay) and requires large, expensive memory buffering capabilities.

Institute of Technology Sligo - Dept of Computing Packet Switched Services  Frame Relay (Connectionless)  More efficient and much faster than X.25  Packet switched version of ISDN (which is circuit switched); data rates up to Mbps with 56kbps and 384kbps being the most popular  Used mostly to forward LAN IP and IPX packets but can be used to forward other types of traffic  Primary competitive advantage is its low cost

Institute of Technology Sligo - Dept of Computing WAN Technologies Overview Dedicated T1, E1, T3, E3 xDSL SONET Analog Dial-up modems Cable modems Wireless Switched Circuit Switched POTS ISDN Packet Switched X.25 Frame Relay Cell Switched ATM SMDS

Institute of Technology Sligo - Dept of Computing Cell Switched Services  Asynchronous Transfer Mode (ATM)  Relatively new WAN Technology related to broadband ISDN; max. bandwidth = 622 Mbps  Developed in order to provide one technology for both WANs and LANs to transport data, video, and voice. (High Cost)  Key Benefits:  One network for all traffic--voice, data, video  Compatible with current wiring infrastructure (cable plant)  Very flexible and scalable  Simplifies network management

Institute of Technology Sligo - Dept of Computing Cell Switched Services  Switched Multimegabit Data Service (SMDS)  Closely related to ATM; SMDS is the MAN (Metropolitan Area Network) implementation of ATM  High Cost with max. bandwidth Mbps

Institute of Technology Sligo - Dept of Computing WAN Technologies Review

Institute of Technology Sligo - Dept of Computing Router Basics

Institute of Technology Sligo - Dept of Computing Internal Components RAMNVRAMFlashROM Interfaces Console Auxiliary

Institute of Technology Sligo - Dept of ComputingRAM  Temporary storage for router configuration files  RAM content is lost on power down or restart  Stores...  Routing tables  ARP cache  Fast switching cache  Packet buffering  And Packet hold queues

Institute of Technology Sligo - Dept of ComputingNVRAM  Non-volatile RAM  Stores backup/startup configuration files  Content is not lost when router is powered down or restarted.

Institute of Technology Sligo - Dept of ComputingFlash  EEPROM (Electronically Erasable Programmable Read-Only Memory)  Holds the Cisco IOS (Internet Operating System)  Allows updating of software without replacing the Flash chip  Multiple versions of IOS can be stored  Retained on power down

Institute of Technology Sligo - Dept of ComputingROM  Contains POST (Power On Self Test)  A bootstrap program (loads the Cisco IOS)  And operating system software  Backup, trimmed down version of the IOS  Upgrades require installing new chip set

Institute of Technology Sligo - Dept of ComputingInterfaces  Network connections through which packets enter and exit the router  Attached to the motherboard or as separate modules.

Institute of Technology Sligo - Dept of ComputingLabs  Before moving on to Ch. 3, make sure you have done both of the required labs for Ch. 2  Lab  Lab

Institute of Technology Sligo - Dept of Computing Router User Interface

Institute of Technology Sligo - Dept of Computing User EXEC Modes  User mode  Limited mode used for checking the routers status, looking at routing tables, etc.  You cannot configure the router  Once you’ve typed the password to enter user mode, you will see the > prompt. The word “Router” will be the name of the router. Password: Router> Means you’re in user mode

Institute of Technology Sligo - Dept of Computing Privileged EXEC Modes  Privileged mode  Does everything User mode does  Full power to configure the router  In user mode, you enter the command “enable” and then the privileged password Router> enable Password: Router# Means you’re in privileged mode

Institute of Technology Sligo - Dept of Computing Command Lists  To get a list of commands available in either user mode or privileged mode, enter a ? at the prompt. Router> ? Router# ?  Since the available commands will be more than the screen can hold, you will get the --More-- message at the bottom.  Hitting the space bar will advance the screen to show the next page.

Institute of Technology Sligo - Dept of Computing ip flash: interfaces ipx version parser Router# show ? Getting Help on a Command  The ? can be used with a partial command to learn all the available commands that match what you entered.  To use this help feature, enter the partial command, then tap the space bar, then type ?  For example... The Router returned all the available commands for “show”

Institute of Technology Sligo - Dept of Computing Error Indicator  When you’ve entered an error in the command string, a carat (^) symbol will indicate where the error occurred.  For example... Router# show runing-config ^ % Invalid input detected at the ‘^’ marker

Institute of Technology Sligo - Dept of ComputingLabs  Before taking the Ch. 2/3 test, make sure you have done both of the required labs for Ch. 3  Lab  Lab 3.2.2