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Enterprise Networks

08.2018

Wi-Fi Radio Configuration & Measurements

This post discusses selected practical aspects of Wi-Fi systems including: explanation of some parameters and factors that the network performance is impacted by; showing how to configure some of the parameters them using CISCO Wireless LAN Controller; presenting simulated scenarios to show some examples of radio measurements.

06.2018

Cisco WLC does not switch to newly added Radius server

Problem description I came across one of customer’s problem with Cisco wireless controller and 802.1x network. Radius service was driven by NPS (Microsoft Windows Radius). After setup of new NPS server customer configured the second Radius server on WLC swaping the radius server priority (on the first place under the WLAN Security -> Advanced tab […]

Author: Marcin Bialy
05.2018

Cisco AP can’t join the WLC controller… DTLS handshake failure.

The problem, network components and topology I recently faced the issue with AP join to vWLC. Cisco 2700 AP could not join to newly installed Cisco vWLC controller. Coleague asked me to take a look and explained the topology. The vWLC was located in Grandmetric DC Testing Labs whereas Cisco CAP-2700 was located at Grandmetric […]

Author: Marcin Bialy
04.2018

IPSec tunnel between Cisco IOS router and AWS VPC. Static VTI and crypto map with HSRP redundancy.

Recently i was asked to advise in the following scenario: VPN tunnel between AWS VPC and Cisco IOS routers on DC prem. Nothing sophisticated but: Two ISR 4k, HSRP VPN redundancy, legacy crypto maps in production (several working vpns) and Static VTI (AWS). Two Crypto structures sourced from one HSRP. I have put the results on blog.

Author: Marcin Bialy
04.2018

Troubleshooting FMC and Firepower Sensor communication

In this post we are going to focus on the scripts included in FTD and FMC operating systems that help to troubleshoot connections between FTD sensors and Firepower Management Center. As they are run from the “expert mode” (super user), it is better that you have a deep understanding of any potential impact on the […]

Author: Ivan Radev
04.2018

Dealing with Cisco Firepower Management Center (FMC) and Firepower sensor communication. Registration process.

This post should help you to understand the Firepower sensor registration in FMC process and uncover the communication specifics between firepower components. I will also give you some additional hints what to check to verify the registration. In order to make troubleshooting easier there will be dedicated troubleshooting post later on.   1. High level […]

Author: Ivan Radev
03.2018

How does a switch work?

To explain how does a switch work, let me make an introduction to the subject by explaining background of TCP/IP stack layers, frame and the purpose of switch. This will help you to understand the exact operation of switch which is the main agenda here. To allow communication between billions of computer devices, intermediate network […]

Author: Marcin Bialy
12.2017

What is Software Defined Network (SDN)?

No 1 principle of SDN is to separate the devices abstraction that transport the network traffic (forwarding plane) from control plane abstraction, in such a way that it enables to control the network functions by the means of software layer. In practice it can be systems, web applications, and scripts.

Author: Marcin Bialy
10.2017

Which Next Generation Firewall to choose – Report

Often, during meetings with clients, network engineers and security specialist there is following question posed: “What firewall product best suits their environment and which one is the best currently on the market?” Like almost always the answer could be “Well, it depends” …

Author: Marcin Bialy
08.2017

Where to use static and where to use dynamic routing?

Routing is the crucial process in IP networks responsible for IP prefix propagation and keeping the whole network topology in order. Having billions of IP addresses divided into many different subnets, without routing there would be muddle that will prevent the whole Internet from working. So, routing is like the set of rules that allows localize particular IP network and IP addresses that belongs to that network.

Author: Marcin Bialy
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