In this blog I usually share practical configuration examples and how-to guides about Cisco networking devices and technologies (routers, switches, ASA firewalls etc). However, there are a lot of people out there interested in more generic and fundamental networking topics because they either just starting out in this field or are learning the basic concepts […]
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As Network Engineers we need to be versatile and troubleshooting-savvy in our work environment. In addition to having strong knowledge of networking protocols and commands on network devices (routers, switches, firewalls etc) we need also to have very good knowledge of IP and other networking related commands on end-point devices such as Windows computers, Linux […]
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Online learning platforms exploded in popularity a few years ago. Recently, a handful of platforms have fought their way to the top. Both Udemy and Coursera often come up in conversations about the best learning platforms. A given person might assume they offer a similar experience and similar courses. However, each platform is geared toward […]
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Ethernet Switches are the backbone of any network, no matter if it’s a home, office or enterprise network. Even though most of our communication nowadays is carried out wirelessly (WiFi, Mobile 3G-4G-5G etc), there ARE a lot of cases whereby network connectivity has to be implemented the “old-school” wired way. And that’s where Ethernet Switches […]
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The scenario of configuring site-to-site VPN between two Cisco Adaptive Security Appliances is often used by companies that have more than one geographical location sharing the same resources, documents, servers, etc. The Cisco ASA is often used as VPN terminator, supporting a variety of VPN types and protocols. In this tutorial, we are going to […]
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UPDATED: 2019 – Cisco Catalyst switches equipped with the Enhanced Multilayer Image (EMI) can work as Layer 3 devices with full routing capabilities. For example, some switch models that support layer 3 routing are the 3550, 3750, 3560 etc. On a Layer3-capable switch, the port interfaces work as Layer 2 access ports by default, but you […]
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With the older Cisco PIX firewall appliances, there was no way for traffic to enter a specific interface and then exit back from the same interface again. With the new Cisco ASA models, this is also not supported by default, but you can enable this functionality with the same-security-traffic permit intra-interface command. The schematic above […]
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Policy Based Routing (PBR) is a feature that has been supported on Cisco Routers for ages. However, Cisco ASA firewalls didn’t support this until version 9.4.1 and later. Finally Cisco acknowledged the usefulness of PBR on firewall devices and has implemented this on ASA as well. In this article I will show you how to […]
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The depletion of the public IPv4 address space has forced the internet community to think about alternative ways of addressing networked hosts. Network Address Translation (NAT) therefore was introduced to overcome these addressing problems that occurred with the rapid expansion of the Internet. Even if NAT was suggested as a temporary solution, it has been […]
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I should have written this article from the very beginning of starting this blog because it is one of the most fundamental configuration steps for managing a Cisco networking device (router, switch, firewall etc). Disabling Telnet and enabling SSH on a networking device is also a step forward in increasing security in the whole network. […]
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Although this is a Cisco networks dedicated blog, I decided to start a series of tutorial posts about a general technology which is not directly related to Cisco but it is a field in which Cisco is again a major player. This is IP Telephony and Voice over IP (VoIP). Image Source The two terms, […]
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Updated: 2018 In this post I will explain how to provide routing between two VLANs on a simple Layer 2 switch using a Cisco router with just one interface. This is called also Router-on-a-stick. This configuration is usually asked as a question in CCNA exams, so I hope it will be helpful for people preparing […]
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In this article we will discuss the similarities and differences between the 3 “First Hop Redundancy” protocols supported by Cisco devices. These are Hot Standby Router Protocol (HSRP), Virtual Router Redundancy Protocol (VRRP) and Gateway Load Balancing Protocol (GLBP). The main purpose of the above protocols is to provide redundancy to the default gateway (router […]
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