Chapter 5 Router and IOS Basics

Transcription

1 Chapter 5 Router and IOS Basics

2 Benefits of Routing Routers provide Packet filtering Connections between local networks Traffic control Wide area network (WAN) connections Routers operate at the Network layer of the OSI reference model Because of Network layer addressing, routers can direct packets to both local and remote segments 2

3 Cisco Router User Interface Cisco Internetwork Operating System (IOS) Provides a command-line interface (CLI) Allows network operators to check the status of the router and network administrators to manage and configure the router You can access a router in several different ways Console port (also known as the console) Auxiliary port (AUX) Virtual terminals (VTY) Trivial File Transfer Protocol (TFTP) server 3

4 4

5 5

6 System Configuration Dialog If the router has not been configured previously, or if the startup file has been erased The Cisco IOS will prompt you to run the initial configuration dialog after the router boots The system configuration dialog presents a series of prompts that guide you through the initial configuration for the router 6

7 7

8 User Interface The initial prompt consists of two parts: The host name of the router followed by the greater than symbol (>) Default: router> User EXEC mode (or user mode) When the prompt displayed is the greater than symbol Network operator can check router status and review several of the router settings 8

9 9

10 User Interface (continued) The question mark activates context-sensitive Help on the Cisco router User mode does not allow you to configure the router To do this, you must go into the privileged EXEC mode To enter privileged EXEC, you can type the enable command at the user mode prompt Next, you may be prompted for a password Greater than symbol (>) changes to a pound sign (#) 10

11 User Interface (continued) You can do a few things at this prompt Setup: the setup command will cause the router to enter the system configuration dialog Copy: configurations can be copied from TFTP servers to the router and therefore change the router configuration Erase: configuration files as well as the entire IOS can be erased 11

12 Configuration Modes Global configuration mode Accessed by typing configure terminal at the enable mode prompt Interface configuration mode Allows you to configure the Ethernet and serial interfaces on your router Line configuration mode Allows you to configure the virtual terminals, console, and AUX lines that let you access the router 12

13 13

14 Configuration Modes (continued) Typing exit will take you back one level Typing end or pressing the Ctrl+Z keys will take you all the way back to the enable prompt Often, you can discover abbreviated commands by simply trying them The router will show you the point at which you entered an incorrect character 14

15 Configuration Modes (continued) 15

16 Plethora of Passwords 16

17 Plethora of Passwords (continued) Enable Password and Enable Secret Password configuration You can set both passwords from the global configuration mode prompt Because it is encrypted, the enable secret password is more secure than the enable password You can type no enable secret and no enable password at the global configuration mode prompt To remove the enable secret and enable passwords 17

18 Plethora of Passwords (continued) 18

19 19

20 Plethora of Passwords (continued) Setting Line passwords Line passwords are the first line of defense against unauthorized intrusion into the router You can set passwords for each line used to configure the router Configure the console line password Enter line configuration mode You can also configure passwords on the five virtual terminal lines that exist on every router In much the same way as on the console port 20

21 Plethora of Passwords (continued) 21

22 Plethora of Passwords (continued) 22

23 Plethora of Passwords (continued) 23

24 Enhanced Editing By default, the router supports enhanced editing features that allow you to modify lengthy commands The enhanced editing commands let you jump to the beginning or end of a command line You can also jump forward or back, character by character, or word by word You can turn off the enhanced editing features by typing terminal no editing at either the user EXEC or the privileged EXEC prompts You can turn on terminal editing by typing terminal editing 24

25 Enhanced Editing (continued) 25

26 Command History Command history Allows you to retrieve previously typed commands You can see up to 10 previously typed commands by typing show history From either the user EXEC or privileged EXEC mode To modify the number of commands stored by the router, you can use the terminal command Up to 256 previous commands Type terminal history size n 26

27 Configuring Router Identification Router host name Default host name is router To set the router host name, type hostname followed by the name that you want to set Configure a banner A banner is a message that you can configure to display each time someone attempts to log in to the router Enter global configuration mode by typing config t Then type banner motd, followed by a space and a delimiting character 27

28 Configuring Router Identification (continued) 28

29 Configuring Router Identification (continued) 29

30 Configuring Router Identification (continued) Configure an interface description Use the description command The interface description helps you remember which network the interface services 30

31 Configuring the Time and Date Use the clock set command in enable mode to configure the time You must be in global configuration mode to configure the time zone 31

32 Router Components This section discusses the hardware elements of the router: ROM Flash memory NVRAM RAM/DRAM Interfaces 32

33 ROM Read-only memory (ROM) Loads the bootstrap program that initializes the router s basic hardware components Not modified during normal operations, but it can be upgraded with special plug-in chips The content of ROM is maintained even when the router is rebooted The ROM monitor firmware runs when the router is turned on or rebooted 33

34 Flash Memory Flash memory A type of erasable, programmable, read-only memory (EPROM) Not typically modified during normal operations However, it can be upgraded or erased when necessary The content of flash memory is maintained even when the router is rebooted Flash memory Contains the working copy of the current Cisco IOS Is the component that initializes the IOS for normal router operations 34

35 35

36 NVRAM Nonvolatile random access memory (NVRAM) A special type of RAM that is not cleared when the router is rebooted The startup configuration file for the router is stored in NVRAM by default This is the first file created by the person who sets up the router The Cisco IOS uses the configuration file in NVRAM during the router boot process 36

37 RAM/DRAM Random access memory (RAM) Also known as dynamic random access memory (DRAM) A volatile hardware component Its information is not maintained in the event of a router reboot Changes to the router s running configuration take place in RAM/DRAM 37

38 RAM/DRAM (continued) The IOS contains commands to view each of the router s components show running-config show memory show buffers show startup-config Copy running-config startup-config Abbreviated as Copy run start 38

39 39

40 Interfaces A router can ship with a variety of configurable interfaces A common interface is Ethernet0 Other types of interfaces include: Token Ring Basic Rate Interface (BRI) Asynchronous Transfer Mode (ATM) Fiber Distributed Data Interface (FDDI) Channel Interface Processor (CIP) for Systems Network Architecture (SNA) High-Speed Serial Interface (HSSI) 40

41 41