Browsing articles in "Tutorial"
Feb
1
2016
Using Cisco ISE API to write web interface
Cisco-API

In the last three months, I was involved in a project concerning the migration of the authentication system (dot1x) from Cisco ACS to Cisco ISE (1.4). At the end of this work, the account told me if it is possible to have a web interface with the active sessions, the devices authenticated via Dot1x and the devices authenticated via MAB. Reading the official guide, I found that Cisco ISE has embedded API. Cool! This what I needed!

Oct
28
2015
SecureCRT: How to import sessions via CSV file
SecureCRT-How-to-import-sessions-via-CSV-file-4

In my opinion, one of the best Telnet/Serial/SSH client is SecureCRT, that provides rock-solid terminal emulation for computing professionals, raising productivity with advanced session management and a host of ways to save time and streamline repetitive tasks. I recently had the need to import a hundred devices in SecureCRT, but I didn’t know how to do it. Surfing the web, I found a helpful python script to import it via CSV! Three components are required: SecureCRT (obviously), the script and the CSV file.

Aug
20
2015
Is static port channel a good idea?
Is-static-port-channel-a-good-idea-loop

During my CCIE R&S studies (CCIE Routing and Switching v5.0 Official Cert Guide, Volume 1), I have discovered an unexpected behavior of the static port channel: a Layer2 loop! Obviously, in order for that happen, several things must happen. Suppose to have three switches:   The Ciscozine-ROOT switch, as the word suggest, is the root bridge (priority 4096); the Ciscozine-ROOT_SEC is the “backup root bridge” (priority 8192), while the Ciscozine-SW has the default priority.

Apr
21
2015
Send WhatsApp alert during a network fault
whatsapp-alert-network-fault

A good network engineer must react quickly during a fault. On the market, there are several solutions to monitor the network malfunctions: HP Openview, Solarwinds, PRTG and other solutions (open source or not). Generally, when an alert/warning is detected an event is triggered: email, SMS or text to a monitor. But why don’t you send these messages via whatsapp? It’s free and can reach everyone, everywhere! What you need: PHP with openssl extension enabled WART WhatsAPI-Official SIM In this tutorial, I use XAMPP Portable version 1.8.3 (http://sourceforge.net/projects/xampp/) on a Windows7 64bit machine. Note: The WhatsAPI-Official requires openssl extension enabled in the PHP settings; whitout this library the script cannot work! […]

Jan
29
2015
Cisco VSS: Failure scenarios
VSS-recovery-1

In the last article, I explained how to configure the Cisco 6500 in VSS configuration, but how does the VSS reacts during a failure? There are three possible scenarios: Link failure within a multichassis Cisco etherchannel link Active supervisor engine failure VSL failure Scenario #1: Link failure within a multichassis Cisco etherchannel link Availability is not affected for those data flows that do not use the failed link. For those traffic flows that use the failed link, the effect consists of the time it takes to detect the link failure and reprogram the indices within the system.

Nov
26
2014
Cisco 6500 VSS configuration
Cisco-6500-VSS-Configuration-MEC-Physical

The Cisco Catalyst 6500 Series Virtual Switching System (VSS) allows the clustering of two chassis together into a single, logical entity. This technology allows for enhancements in all areas of network design, including high availability, scalability, management, and maintenance. The Virtual Switching System is created by converting two standalone Catalyst 6500 systems to a Virtual Switching System. The conversion is a one-time process that requires a few simple configuration steps and a system reload. Once the individual chassis reload, they are converted into the Virtual Switching System. All control plane functions are centrally managed by the active supervisor engine of the active virtual […]

Nov
2
2014
How to log everything with SecureCRT
how-to-log-securecrt-3

Unlike my technical articles about configurations, protocols and so on, in this tutorial I will explain how to log automatically all SecureCRT sessions. For those that are unaware, SecureCRT is one of the best SSH/telnet client. The question is “why save everything?” In my opinion, a good approach to work with many devices (network, security, …) is to save everything (show command, configuration command and so on..). This method gives several benefits, for instance when: The telnet/SSH client buffer is full Something goes wrong You mistakenly close SecureCRT You want to check what you have done

Jul
15
2014
Send Cisco commands via SNMP
Send-command-via-SNMP-2

In the article “How to save configurations using SNMP“, I have explained how to get the Cisco configuration using SNMP. Now, I explain how to send commands via SNMP using the “ciscoConfigCopyMIB” MIB;  with this MIB, you can replace running/startup configuration, send commands, save the “show” output or reload the device. OK, let’s start :) First of all, check if your PC/Server has the SNMP suite; if not, install the net-snmp software (http://net-snmp.sourceforge.net/).

May
23
2014
How to upgrade a Cisco stack
How-to-upgrade-a-Cisco-stack

One of the task of a good Network engineer is update the Cisco IOS to avoid bugs and to have new features; but what is the correct procedure to upgrade a Cisco stack, for instance two 2960 switches in stack? There are two main methods to upgrade the IOS: TAR image BIN image TAR image The .tar file is an archive file from which both the IOS image and the CMS files are extracted during the upgrade process. If you want to manage switches or clusters of switches through a web interface (HTML), this is the only file you need to download.

May
1
2014
Speed up your console
Speed-up-your-console-connection-3640

Generally to upgrade/downgrade an IOS, you use the classical ftp/tftp transfer from a laptop to a router/switch; unfortunately, there are some cases where this way is not possible, so the only solution is to use the console. Suppose you have to upload an image of about 20Mb. On a 9600bps intereface, the time required to upload this image is about 35minutes (20000000/9600)! Oh my God! Fortunately Cisco permit to change the console speed using the command “speed”. By default the console interface works at 9600bps: Ciscozine#sh line console 0 Tty Line Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int […]