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Cisco pipe Command Examples with Regular Expressions

We use the pipe (|) command more frequently on Cisco devices to get specific output of show & troubleshooting commands. Below are the available options for Pipe (|) command from Cisco ASR1002 Router. Cisco_Router#sh run | ? append   Append redirected output to URL (URLs supporting append operationonly) begin   Begin with the line that matches count  Count number of lines which match regexp exclud   eExclude lines that match format   Format the output using the specified spec file include   Include lines that match redirect  Redirect output to URL section   Filter a section of output tee    Copy output to URL Append option will send all output from the show command to be appended to a file already created at either a local (flash: disk:) or remote (ftp: tftp:) location. Example: The below command would copy the output off the show running-config command to an ftp server […]

How to trace physical interface with MAC/IP address in Cisco Devices

In this post I will explain the steps to find the client/end user computer connected physical interface in large Network environment with multiple Access Switches connecting to the core switches or routers. This will help you to trace and troubleshoot devices like a PC or a laptop or other end devices. This is not a difficult task but can certainly be time consuming. You can trace the physical interface by using MAC address or IP address. You can find the MAC address with “sh ip arp” command of particular IP address in gateway router. Let’s start with an IP address. Find out gateway router while checking traceroute to the IP address then login into second hop IP address from end and enter “sh ip arp X.X.X.X” command. C:\>tracert Tracing route to over a maximum of 30 hops 1     1 ms     1 ms     2 ms 2     1 ms    <1 ms    <1 […]

How to Configure Cisco Alias Commands on Cisco Router

In general we use commands like show ip interface brief, copy run start, configure terminal, show running-config, etc repeatedly. To save time and the repetition of entering the same command for multiple times, you can use a “alias Command“. Cisco IOS permits you to configure a shortcut command to complex command. An alias command can be configured to do anything that can be done at the command line, but an alias cannot move between modes, type in passwords, or perform any interactive functions. Below Table contains default Command Aliases for Cisco Original Commands. Default Cisco Alias Commands: h help lo Logout p ping s show U or un undebug w where Find/show Default alias Commands on Cisco Router Find default alias commands on Cisco Router with show aliases command. Cisco-Router#sh aliases Exec mode aliases: h                     help lo                    logout p                     ping r                     resume s                     show u                     undebug un                    undebug w                     where Cisco-Router# Configure some Cisco alias commands […]

How to Configure Schedule Reload on Cisco Router or Switch

Sometimes you may locked out and unable to access the device after you have made some configuration changes on the Cisco Router or Switch. The good news is that you didn’t write the configuration so you just need to reload/power cycle the device. If the device is at a remote site you can configure a schedule reload at non traffic timings with proper authorization and also you have option to cancel the schedule Reload. Cisco#reload ? at            Reload at a specific time/date cancel    Cancel pending reload in            Reload after a time interval reason    Reload reason warm       Reload should be warm <cr> You can configure schedule Reload in two ways. One way is you can schedule the reload to happen at a specific time of day* (reload at) and Second way is at the end of a certain […]

Analyze Reliability, Txload and Rxload on Cisco Router or Switch interface

Reliability: Reliability means the Layer 2 keepalives are sent and received with 0% loss on the link. Reliability of the interface is 255/255 means good news and link is healthy. It is calculated as an exponential average over 5 minutes and as a fraction of 255 (255/255 is 100 percent reliability). Txload and Rxload: You can measure transmit and receive traffic on any interface of Cisco Router or Switch. You can find txload and rxload fields of Cisco IOS’s command sh interface <> output and it will be in a number from 0 to 255. You then use that to calculate your bandwidth. txload and rxload roughly measure the amount of traffic passing out of and into an interface, respectively, relative to its perceived bandwidth. As an example, if it is a 100 Mbps Fastethernet interface, txload is 126/255 it means transmit traffic from this interface would be 50 Mbps. […]

Default Cisco Router Boot-up sequence/process

Cisco Router can boot-up Cisco IOS from below locations: Flash memory TFTP server ROM (not full Cisco IOS) Cisco Router Default Boot Sequence/Process for locate Cisco IOS: NVRAM Flash (sequential) TFTP server (network boot) ROM (partial IOS) Note: Cisco boot system commands can be used to specify the primary IOS source and fallback sequences. Complete Cisco Router Boot-up  sequence and locating the Cisco IOS: 1. POST (power on self test) and  Bootstrap code executed       The POST is a process is used to test the Router hardware. After POST, the bootstrap program is loaded.  2. Locate Cisco IOS  Software and Loads it into RAM of Cisco Router The bootstrap program locates the Cisco IOS software and loads it into RAM. Cisco IOS files can be located in one of three places: flash memory, a TFTP server, or another location indicated in the startup configuration file. The Cisco IOS software loads from flash […]