Embedded Event Manager (EEM) Tutorial

April 29th, 2021 in ENCOR Knowledge

EEM (Embedded Event Manager) is a software component of Cisco that allows network administrators to automate many tasks. EEM is like a programming language with “if {condition} then {action}” statement. If your condition is met then some “actions” will be performed automatically on the device.

An EEM consists of two major components:
+ Event: Defines the event to be monitored
+ Action: Defines action to be taken when the event is triggered

There are three steps to creating an EEM applet.
Step 1. Create the applet and give it a name with the command “event manager applet applet-name
Step 2 (Optional). Tell the applet what to look out for (just optional as some applets do not need to look out anything), usually with “event cli pattern” command
Step 3. Define action to be taken when the event is triggered in step 2, usually with “action” or “set” command.

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LISP Tutorial

October 16th, 2020 in ENCOR Knowledge

In the Internet nowadays, the IPv4 or IPv6 address of a device represents both its identity and location. When a host moves from one location to another location, it is assigned a different IPv4 or IPv6 address, which overloads the location/identity semantic. We can say routing in the Internet today is like putting direction signs about every city in the world at every crossing.

Locator ID Separation Protocol (LISP) solves this issue by separating the location and identity of a device through the Routing locator (RLOC) and Endpoint identifier (EID):

+ Endpoint identifiers (EIDs) – assigned to end hosts.
+ Routing locators (RLOCs) – assigned to devices (primarily routers) that make up the global routing system.

With LISP, the change in location of a device does not result in a change in its identity. In other words, when the device moves from one location to another, it still keeps its IPv4 or IPv6 address, which is the EID part. Only the RLOC (which represents the IP address of the connected router) changes. In order to do so, LISP provides the distributed architecture EID-to-RLOC mapping that maps EIDs to RLOCs.

LISP_Traditional_IP_address.jpg

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JSON Web Token (JWT) Tutorial

August 12th, 2020 in ENCOR Knowledge

As you know, the World Wide Web we know today is based on HTTP (which includes both HTTP and HTTPS). If you are reading this tutorial then surely you had to access to networktut.com via HTTP. But HTTP is a stateless protocol so if you logged in then visiting another page on the same site, you would be forced to log in again since HTTP does not save your login status. In order to solve this problem, there are two popular ways to help keep the information you provided for later use: Session-based authentication (sometime called Cookie-based authentication) and Token-based authentication. In this tutorial we will learn both and the difference between them.

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NetFlow Tutorial

July 17th, 2020 in ENCOR Knowledge

One of the most important tasks of a network administrator is to monitor the health of our networks, learn how our bandwidth is being used, what applications are consuming it, when it needs upgrade… Although monitoring protocols like SNMP and SPAN (port mirroring) can help us answer some questions but they are not enough to give us an insightful view of our networks. Luckily we have another amazing tool: NetFlow!

NetFlow is a networking analysis protocol that gives the ability to collect detailed information about network traffic as it flows through a router interface. NetFlow helps network administrators answers the questions of who (users), what (application), when (time of day), where (source and destination IP addresses) and how network traffic is flowing.

Let’s take an example! In the topology below, when traffic from Network 1, 2, 3… passes through the interfaces of a NetFlow enabled device, relevant information is captured and stored in the NetFlow cache. NetFlow collects IP traffic information as records and sends them to a NetFlow collector for traffic flow analysis.

NetFlow_example.jpg

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