1 © 2004, Cisco Systems, Inc. All rights reserved. CCNA 2 v3.1 Module 1 WANs and Routers

222 © 2004, Cisco Systems, Inc. All rights reserved. Objectives

333 © 2004, Cisco Systems, Inc. All rights reserved. Introduction to WANs A WAN is a data communications network that spans a large geographic area such as a state, province, or country Often use transmission facilities provided by common carriers such as telephone companies Use serial connections of various types to access bandwidth over large geographic areas Operate at the physical layer and the data link layer of the OSI reference model Provide for the exchange of data packets and frames between routers and switches and the LANs it support.

444 © 2004, Cisco Systems, Inc. All rights reserved. WAN Devices

555 © 2004, Cisco Systems, Inc. All rights reserved. WAN Devices  Routers offer many services, including internetworking and WAN interface ports  A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device about the size of an external modem that converts a digital data frame from the communications technology used on a LAN into a frame appropriate to a WAN and vice versa  Communication servers concentrate dial in and dial out user communication

666 © 2004, Cisco Systems, Inc. All rights reserved. WAN Physical Layer Standard and Protocols The standards and protocols or primary functions of a WAN operate at the physical layer and at the data link layer This does not mean that the other five layers of the OSI model are not found in a WAN It simply means that the standards and protocols that define a WAN connection are typically found at the physical and data link layers Layer 1 and Layer 2 WAN standards and protocols are different than the Layer 1 and Layer 2 LAN standards and protocols

777 © 2004, Cisco Systems, Inc. All rights reserved. WAN Physical Layer Standard and Protocols ( Continued ) The WAN physical layer describes the interface between the data terminal equipment (DTE) and the data circuit- terminating equipment (DCE) Generally, the DCE is the service provider and the DTE is the attached device WAN standards and protocols are defined and managed by a number of recognized authorities, including the following agencies:

888 © 2004, Cisco Systems, Inc. All rights reserved. WAN Physical Layer Standard and Protocols ( Continued ) 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) Examples: EIA/TIA-449, V.24, V.35, X.21, G.703, EIA- 530, ISDN, T1, T3, E1, E3, xDSL, SONET

999 © 2004, Cisco Systems, Inc. All rights reserved. WAN Data Link Layer Standards and Protocols WAN data link protocols describe how frames are carried between systems Examples : 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

10 © 2004, Cisco Systems, Inc. All rights reserved. WAN Services

11 © 2004, Cisco Systems, Inc. All rights reserved. Data Link Encapsulations

12 © 2004, Cisco Systems, Inc. All rights reserved. Routers A router is a special type of computer It has the same basic components as a standard desktop PC It has a CPU, memory, a system bus, and various input/output interfaces However, routers are designed to perform some very specific functions that are not typically performed by desktop computers Router operates at Layer 3 of the OSI model, making decisions based on network addresses

13 © 2004, Cisco Systems, Inc. All rights reserved. Routers (Continued) The two main functions of a router are the selection of best path and the switching of packets to the proper interface To accomplish this, routers build routing tables and exchange network information with other routers An administrator can configure static routes to maintain routing tables However, most routing tables are maintained dynamically through the use of a routing protocol that exchanges network topology information with other routers

14 © 2004, Cisco Systems, Inc. All rights reserved. Internal Configuration Components

15 © 2004, Cisco Systems, Inc. All rights reserved. RAM Provides temporary memory for the configuration file of a router while the router is powered on Loses content when a router is powered down or restarted Stores routing tables Maintains packet-hold queues

16 © 2004, Cisco Systems, Inc. All rights reserved. NVRAM Provides storage for the startup configuration file Retains content when a router is powered down or restarted

17 © 2004, Cisco Systems, Inc. All rights reserved. Flash Memory Holds the IOS (Internetwork operating system) image Allows software to be updated without removing and replacing chips on the processor Retains content when a router is powered down or restarted Can store multiple versions of IOS software A type of electrically erasable programmable read- only memory (EEPROM)

18 © 2004, Cisco Systems, Inc. All rights reserved. ROM Maintains instructions 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

19 © 2004, Cisco Systems, Inc. All rights reserved. Segmentation with Routers

20 © 2004, Cisco Systems, Inc. All rights reserved. WAN Connection

21 © 2004, Cisco Systems, Inc. All rights reserved. Routers Connected by WAN Technologies

22 © 2004, Cisco Systems, Inc. All rights reserved. Path Determination

23 © 2004, Cisco Systems, Inc. All rights reserved. Role a Router in WAN One of the roles of a router in a WAN is to route packets at Layer 3 Router LAN or WAN device! It also provides connections between the various WAN physical and data-link standards For example, a router may have an ISDN interface that uses PPP encapsulation and a serial interface at the end of a T1 line that uses Frame Relay encapsulation The router must be able to move a stream of bits from one type of service, such as ISDN, to another, such as a T1, and change the data link encapsulation from PPP to Frame Relay.

24 © 2004, Cisco Systems, Inc. All rights reserved. Internetwork Routers Any internetwork router must include the following: Consistent end-to-end addressing Addresses that represent network topologies Best path selection Dynamic or static routing Switching

25 © 2004, Cisco Systems, Inc. All rights reserved. Router Internal Components

26 © 2004, Cisco Systems, Inc. All rights reserved. Router Internal Components

27 © 2004, Cisco Systems, Inc. All rights reserved. Internal Components of a 2600 Router

28 © 2004, Cisco Systems, Inc. All rights reserved. External Connections on a 2600 Router

29 © 2004, Cisco Systems, Inc. All rights reserved. Router External Connections

30 © 2004, Cisco Systems, Inc. All rights reserved. Computer or Terminal Console Connection

31 © 2004, Cisco Systems, Inc. All rights reserved. Modem Connection to Console or Auxiliary Port

32 © 2004, Cisco Systems, Inc. All rights reserved. Console Port Connections 1.Configure terminal emulation software on the PC for the following: The appropriate com port 9600 baud 8 data bits No parity 1 stop bit No flow control 2.Connect a rollover cable to the router console port (RJ-45 connector). 3.Connect the other end of the rollover cable to the RJ-45 to DB-9 adapter 4.Attach the female DB-9 adapter to a PC.

33 © 2004, Cisco Systems, Inc. All rights reserved. Eight-Pin Connections for Cisco 2600 Series Routers

34 © 2004, Cisco Systems, Inc. All rights reserved. WAN Types

35 © 2004, Cisco Systems, Inc. All rights reserved. Router Serial WAN Connectors

36 © 2004, Cisco Systems, Inc. All rights reserved. DCE Serial Connections

37 © 2004, Cisco Systems, Inc. All rights reserved. Summary