L3 configuring a router

Configuring a Router Objectives • • Basic router configuration The importance of backups and documentation CLI Command Modes Global Configuration Modes Password Configuration enable secret command, which is encrypted, is prefered and overide enable password Configuring an interface Vao mot cong Dat dc IP Mo cong thoat Interfaces status • Router interfaces have 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 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 dat toc ? • On Cisco router, HDLC is the default encapsulation on serial link Router(config-if)#encapsulation phuong thuc ma hoa ? Neu khong dat tu tu dong la HDLC, chi dat tren DCE • By default, serial interface is of DTE device, shutdown and have no ip address • Configure router hostname: Router(config)#hostname Center – dat ten cho rounter Center(config)# Router Commands: Show Router#show version Router#show interfaces Router#show flash RAM NVRAM Flash Internetwork Operating System Router#show processes CPU Router#show protocols Tables 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 • In both privileged EXEC and user EXEC modes, the command show ? provides a list of available show commands 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 changes (yes/no)? no Finishing the Configuration Configuration Standards • A standard is a set of rules or procedures that are either widely used or officially specified • Configuration, security, performance, and other issues must be adequately addressed for the network to function smoothly • Creating standards for network consistency helps reduce network complexity, the amount of unplanned downtime, and exposure to events that may have an impact on network performance Description and Banner • An interface description should be used to notify important information such as a distant router, a circuit number, or a specific network segment • A login banner is a message that is displayed at login and is useful for conveying messages that affect all network users, such as notices of impending system shutdowns Host Name Resolution • Host name resolution is the process that a computer system uses to associate a host name with an IP address • Host names, unlike DNS names, are significant only on the router on which they are configured ip host command Router (config)# ip ip host host hostname hostname [tcp-port [tcp-port number] number] address1 address1 [address2…address8] [address2…address8] • Defines a static hostname-IP mapping ip address command Description hostname name of host, can be a combination of character & number tcp-port number TCP port to connect to when using host name with EXEC connect or telnet commands, default is 23 (telnet) address1 IP address represented by hostname address2…8 (Optional) may specify up to IP addresses ip name-server command Router (config)# ip ip name-server name-server server-addr1 server-addr1 [server-addr2…server-addr6] [server-addr2…server-addr6] • Defines one or more DNS servers ip name-server command Description name-server name of host, can be a combination of character & number server-addr1 IP address of primary name server server-addr2…serveraddr6 (Optional) may specify up to additional IP addresses ip domain-lookup command Router (config)# ip ip domain-lookup domain-lookup • Enables the use of DNS • Enable by default show hosts EXEC command Router# show show hosts hosts display a cached list of HOST table show hosts command Description Host Host name learnt Flag Status of this host name entry permanent (perm) Permanent entry as entered by administrator into router configuration temporary (temp) Host name entry learnt by DNS server (removed after 72 hours of inactivity) OK Entry is valid EX Entry is expired ?? Not sure about this entry, need to re-validate Age Time interval (in hours) router last referred to this entry Type Protocol field (IP, HP-IP) Address(es) Layer address(es) associated with hostname HOST Table Loopback Interface Router (config)# interface interface loopback loopback loopback_interface_number loopback_interface_number • A virtual interface that is always up and allows sessions (BGP, RSRB…) to stay up even if the outbound interface is down • Packets routed to the loopback interface are rerouted back to the router or access server and processed locally •Use loopback interface to simulate an active interface Configuration backup and documentation • Management of device configuration includes the following tasks: – Listing and comparing configuration files on running devices – Storage of configuration files on network servers – Performing software installations and upgrades Configuration File with TFTP server Configuration File with Hyper Terminal • • • • Use terminal length to display all the output from commands at once Start Capture text Show running-config Stop Capture text Summary • Router name, description, banner, hosts • Configure router interface • Router show commands • Backup configuration files