iBGP Introduction
February 5, 2025 - Reading time: 3 minutes
BGP (Border Gateway Protocol) is the backbone of the internet, enabling networks to communicate and exchange routing information. It allows routers to determine the best path for forwarding data between different networks, known as Autonomous Systems (ASes).
There are two types of BGP:
- eBGP (External BGP) – Used between different networks, like between two Internet providers or a company and its internet provider.
- iBGP (Internal BGP) – Used within the same network to keep routing consistent.
In this lesson, we’ll configure iBGP between two routers in the same Autonomous System (AS). Using AS 2350, Router0 will advertise the networks 50.50.50.0/24 and 70.70.0.0/16, and Router1 will receive these routes through the iBGP session and install them into its routing table.
Radius Server Configuration
July 17, 2024 - Reading time: 2 minutes
The previous tutorials covered the basics of AAA (Authentication, Authorization, and Accounting) in Cisco devices. It included an overview of how to configure local authentication, where user credentials are stored directly on each device. We also discussed the principles of using an external authentication server to centralize user credentials and authentication processes, laying the groundwork for a RADIUS server setup with PocketCLI. Understanding these concepts is crucial as we move forward to implementing RADIUS for centralized authentication.
Radius Server Setup
September 10, 2023 - Reading time: ~1 minute
In a Cisco environment, a RADIUS (Remote Authentication Dial-In User Service) server is commonly used to authenticate users for various network services, one of which is network access. This lab introduces using a RADIUS server to allows for centralized user authentication. Instead of maintaining separate user accounts and authentication databases on each network device. All authentication requests are sent to the RADIUS server. This centralization simplifies administration and ensures consistent authentication across the network.
AAA Authentication Using Local Credentials
February 25, 2023 - Reading time: 2 minutes
Cisco AAA (Authentication, Authorization, and Accounting) local authentication is a security feature that allows network administrators to control access to network devices and services by requiring users to provide valid credentials before accessing them. With local authentication, administrators can define user accounts and passwords locally on a network device, rather than relying on external authentication servers.
To configure Cisco AAA local authentication, follow these steps:
Switch Errdisable Recovery
February 27, 2021 - Reading time: 2 minutes
In this tutorial we look at errdisable recovery and highlight it on the PocketCLI Network Simulator. Errdisable recovery is a feature on Cisco switches that allows network administrators to automatically activate an err-disabled port after a specified timeout period.
A common cause for an interface to be placed in err-disable status is a port security violation. Please reference the tutorial Port Security - Configuration for more details. The port in the err-disabled state needs an administrator to manually restore the port back to operation. Activation of the port will be accomplished by issuing the command shutdown followed by the no shutdown command.
The topology below will be used for this tutorial:
Spanning Tree Protocol
November 23, 2020 - Reading time: 2 minutes
By default, all Cisco switches have Spanning Tree Protocol (STP) enabled. However, you can choose to configure STP on your switches manually.
STP is used by switches to prevent loops (broadcast storms) from disrupting local area networks. It ensures that there is only one logical path between all destinations on the network, which is achieved by disabling unwanted paths and blocking ports that could cause the loop.
A switch blocks a port when it detects a loop on the network. On the network segment with switches, one switch is elected to be Root Bridge on the network. Other switches on the network then select one of its ports as Root Port. Also, a Designated Port is chosen on each segment and any other ports are put in Blocking state. We shall follow these same procedure in our manual configurations.
The lab below is used in this tutorial:
