After spending time with cloud platforms like Azure, AWS, and DigitalOcean — as well as Type 2 hypervisors (like VirtualBox) — I decided to try something new: a Type 1 hypervisor installed directly on hardware. My choice? The open-source, free, and powerful Proxmox VE (Virtual Environment). Here’s a step-by-step walkthrough of how I installed and…
Recently, I got a used Cisco 881 router that was already configured (asking for a login and password when it started). The previous owner didn’t remember the credentials, so I had to reset it to factory settings. It turned out to be more difficult than I thought — here’s what I learned. 👇 1️⃣ ROM…
Layer 3 (Network Layer) – Responsible for routing packets between networksIPv4 packet = IPv4 header + payload 🔹 IPv4 Header Fields Field Bits Description Version 4 IP version: 4 for IPv4 (0100), 6 for IPv6 (0110) IHL (Internet Header Length) 4 Header size in 4-byte blocks. Min: 5 (20 bytes), Max: 15 (60 bytes) DSCP…
Default Behavior of Interfaces Device Interface Default When Device is Plugged In Switch No shutdown command Goes up/up automatically Router Has shutdown command Stays admin down/down, must be enabled manually 🟡 Switch Interfaces 🔴 Router Interfaces Interface Status Commands SW1# show ip interface brief // Summary (L1/L2) – works for routers/switches SW1# show interfaces status…
Layer 3 and IP IP Broadcast Binary Conversion Binary to Decimal Decimal to Binary Number Systems Base Description Binary Base-2 → powers of 2 Decimal Base-10 → powers of 10 Hexadecimal Base-16 → powers of 16 IPv4 Address Classes Class Binary Start Range Notes A 0xxxxxxx 1–126 0.0.0.0 reserved, 127.x.x.x is loopback B 10xxxxxx 128–191…
LAN Basics Data Encapsulation: PDUs Ethernet Frame Structure [ Preamble (7) | SFD (1) | Destination MAC (6) | Source MAC (6) | Type/Length (2) | Data | FCS (4) ] Ethernet Header (14 bytes) Preamble + SFD (not technically part of header) Ethernet Trailer (4 bytes) MAC Address (6 bytes) Hexadecimal and Decimal Quick…
CLI (Command-Line Interface) – used to configure switches, routers, and firewallsGUI (Graphical User Interface) Connecting via Console Port Modes Apply Password Password Encryption Configuration Files Save Configuration: Commands Router> enable // enter Privileged EXEC mode Router# configure terminal // enter Global Configuration mode Router(config)# enable password xxx // set password for Privileged EXEC mode Router(config)#…
Model and protocol OSI model Open Systems Interconnection model (open standard), created by ISO, consists of 7 layers Adjacent and Same Layer Interaction L7 (Application Layer) L6 (Presentation Layer) L5 (Session Layer) Data flow in OSI model L4 (Transport Layer) L3 (Network Layer) L2 (Data Link Layer) L1 (Physical Layer) Acronyms for memorizing OSI Please…
Connections and Speed Ethernet Standards (Copper) IEEE 802.3i, 802.3u, 802.3ab, 802.3an – standards with different data transmission speeds and names Speed Name (common) IEEE (standard) Name (informal) 10 Mbps Ethernet 802.3i 10BASE-T 100 Mbps Fast Ethernet 802.3u 100BASE-T 1 Gbps Gigabit Ethernet 802.3ab 1000BASE-T 10 Gbps 10 Gig Ethernet 802.3an 10GBASE-T UTP (Unshielded Twisted Pair)…
A computer network is a digital telecommunications network that allows nodes to share resources. Nodes: Client vs Server Switch Router Firewall A firewall (or a next-generation firewall) monitors and controls network traffic based on configured rules. It can be placed inside (after the router) or outside the network (before the router). There are two types…