Apuntes

  DHCP conflict logging: the true story The on-line configuration help for the ip dhcp conflict logging configuration command ( logging: Record address conflicts in a log file ) is one of the more misleading texts I've found in Cisco IOS (and the CCO documentation is not much better). Here's how it actually works ... If you have configured ip dhcp ping parameters (highly recommended), the router will ping the IP address it intends to allocate to a client before replying to the DHCP request. If the router receives ICMP Echo Reply message (response to ping), the address is obviously in use. If the DHCP conflict logging is enabled (default), the router will log the conflict with a syslog message (not in a separate log file) and put the address on the list of conflicts. The addresses on that list (displayed with show ip dhcp conflict ) are not used in the future (similar to the addresses configured with the ip dhcp excluded-addresses command). To reuse a conflictin...

E LIMINAR PASS ENABLE (MANTENIENDO CONFIGURACION ) - CISCO 2960  Fuente: http://www.cahilig.net/2014/04/14/how-reset-cisco-2960-switch-password-without-losing-your-configuration To  reset  your  Cisco  2960  password , connect your console cable to the switch and open up your terminal emulator software, you can use minicom if you are using Linux. Please visit this  link  on how to  install  and configure minicom using in Fedora/Red Hat/ CentOS  and this  link  if you are using Debian/Ubuntu. Power on the switch while holding the mode button. Release the mode button after you see the screen below in your terminal emulator software. Boot Sector Filesystem (bs) installed, fsid: 2 Base ethernet MAC Address: 1c:1d:86:db:c8:80 Xmodem file system is available. The password-recovery mechanism is enabled. The system has been interrupted prior to initializing the flash filesystem. The following comma...

Auto Backup Cisco Router & Switch with Kron and FTP Server Posted by ethernuno on 05/04/2012 Automatic Backup Cisco Router & Switch with Kron and vsftpd FTP. Briefing: In Cisco routers or switches, Kron lets you schedule an automatic backup task to save your running-configs or startup-configs. Also useful to backup IOS images, boot from FTP, copy SDM/ASDM files, and more. In the first example ill configure kron to copy the running-config to startup-config, every Automatically. The second example ill configure kron to send backups of the running-config to vsftpd FTP server. Issues : In order to copy the running-config to startup-config we need to use write(wr) not “copy running-config startup-config”, this is because kron does not support interactive prompts and the “copy running-config startup-config” command requires interaction. It is important to remember this. Also, kron does not support configuration commands. As for sending files to v...

Reset a Cisco 2960 Switch To Factory Default Settings Flattening a switch before re-deployment is one of those simple tasks that I always find myself having lookup on the web, so I thought I’d save myself some time in future and document it here. Step 1. Connect up your console cable and power on the switch, whilst holding down the “mode” button: This interrupts the boot process before the Flash file system can initialize, and after a short while (continue holding the “mode” button) you will see the following prompt: Using driver version 1 for media type 1 Base ethernet MAC Address: 4c:30:2d:81:ef:80 Xmodem file system is available. The password-recovery mechanism is enabled. The system has been interrupted prior to initializing the flash filesystem. The following commands will initialize the flash filesystem, and finish loading the operating system software: flash_init boot switch: Step 2. Initialize the flash file system with the command : fl...