Browsing articles in "Tutorial"
How to install Cisco ISE using USB or CIMC interface

In one of my last job activities, the customer has requested to reinstall the Cisco ISE appliance (SNS-3495). The first option, a DVD reader, is not feasible due the large ISO image file; in fact, the Cisco ISE Software Version 2.2.0 full installation iso file requires more or less 8Gb. So, how can we install the software? There are two options: Using an USB pendrive(al least 16Gb) Using the Cisco Integrated Management Interface (CIMC)

How to access network devices via Radius server

Suppose you manage hundreds of Cisco devices; how can you connect and secure it against unauthorized access? You can use local username, but it isn’t scalable and granular, or use an AAA Server. In fact, the benefits of AAA are: Increased flexibility and control of access configuration. Scalability. Standardized authentication methods. Multiple backup system. Additionally, AAA provides a modular way of performing the following services:

DDNS: How to manage a device with a dynamic public IP

The DDNS aka Dynamic DNS is an old feature that several routers (non only Cisco devices) have implemented and, in some circumstances, it is very useful. DDNS is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DDNS configuration of its configured hostnames, addresses or other information. It provides two mechanisms to generate or perform DDNS: the IETF standard as defined by RFC 2136 and a generic HTTP using various DNS services. In a nutshell, when this feature can simplify our lifes? When we haven’t a static IP public […]

Nexus HSRP/VRRP active/active with vPC

In the article vPC aka Virtual PortChannel, I explained how vPC works and the benefits that it gives. However, there is another important feature using HSRP/VRRP protocols in the context of vPC: the Layer2 dual–active peer devices. What does it mean? HSRP and VRRP operate in active-active mode from data plane standpoint, as opposed to classical active/standby implementation with STP based network. From a control plane standpoint, active-standby mode still applies for HSRP/VRRP in context of vPC. A characteristic of the active HSRP/VRRP peer device is that it is the only one to respond to ARP requests for HSRP/VRRP VIP […]

vPC aka Virtual PortChannel

The vPC aka virtual Port Channel is a Cisco technology that presents both Nexus paired devices as a unique Layer 2 logical node to a third device. The third device can be a switch, server, or any other networking device that supports link aggregation technology. From a spanning tree standpoint, vPC eliminates STP blocked ports and uses all available uplink bandwidth. Spanning-Tree is used as a fail safe mechanism and does not dictate L2 path for vPC attached devices.  

Using Cisco ISE API to write web interface

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!

SecureCRT: How to import sessions via CSV file

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.

Is static port channel a good idea?

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.

Send WhatsApp alert during a 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 ( on a Windows7 64bit machine. Note: The WhatsAPI-Official requires openssl extension enabled in the PHP settings; whitout this library the script cannot work! […]

Cisco VSS: Failure scenarios

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.