How does the internet work – Networking knowledge project that will tell you all you ever wanted to know about networking from a design, planning, and configuration perspective. Articles are vendor agnostic as much as possible with design solutions objectively analyzed.
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Latest – Most recent 5
- Google Jupiter Data Center Network Fabric – New Way of Building Data Center Network Underlay September 17, 2022
- Cisco DNA Upgrade Issues – Application Update Stuck June 8, 2022
- Cisco Catalyst Stack Upgrade May 8, 2022
- TOP 25 in Cisco IT Blog Awards March 15, 2022
- Switch vSphere Enterprise Plus license to vSphere Standard on a NSX-T enabled cluster December 15, 2021
SDDC – Software Defined Datacenters
- New ACI deployment? Watch out when connecting APICs to Leafs
- What is Cisco ACI?
- CLOS Topology
- ACI MultiPod and how to build MultiDatacenter with Cisco ACI
- ACI MultiPod – Enable Standby APIC
- Setting up Cisco ACI From Scratch
- How to Advertise a Route from ACI Layer2 BD Outside the Fabric?
- Cisco ACI – Configuring by POSTing JSON
- Cisco ACI – API Calls vs JSON POST
- Software-defined data center and what’s the way to do it
- VMware TKGI – Deployment of Harbor Container Registry fails with error
- VMware NSX-T Install Tips & Tricks
- Google Jupiter Data Center Network Fabric – New Way of Building Data Center Network Underlay
- NSX-T Edge Transport Node Packet Capture
- Switch vSphere Enterprise Plus license to vSphere Standard on a NSX-T enabled cluster
Routing – How it works?
- BFD – Sub-second Failure Detection
- MTU and TCP MSS
- Redistribute Static on Juniper & Cisco
- Source-Specific Multicast Configuration
- Unable to access Cisco ASA through AnyConnect VPN?
- VRF – Virtual Routing and Forwarding
- Static Route Load Balance
- Proxy ARP
- TCAM and CAM memory usage inside networking devices
- Solicited-node multicast address
- How can router decide so fast?
- /31 subnet in point-to-point links. Is that possible?
- BGP dampening – punishment for unstable BGP prefixes
- Source-based routing in IPv4 and IPv6 networks
- BGP communities
- ICMP – Internet Control Message Protocol
- Troubleshooting EIGRP Neighbor Relationships
- Forwarding UDP broadcast traffic mechanisms
- Administrative Distance for Static Route is 1 or 0?
- Difference between defining static routes with next-hop address or exit interface
- IPv6 RA Router Advertisement and all the flags inside
- What is static floating route
- PBR – Policy Based Routing using Route map
- MPLS – Multiprotocol Label Switching
- Administrative distance – Which route is the best?
- Difference between Routed and Routing Protocols
- IPv6 Anycast Address type
- How to Advertise a Route from ACI Layer2 BD Outside the Fabric?
- BFD – Sub-second Failure Detection
- Redistribute Static on Juniper & Cisco
- Unable to access Cisco ASA through AnyConnect VPN?
- Juniper vMX Multicast Configuration
- VRF – Virtual Routing and Forwarding
- Static Route Load Balance
- What is route recursion
- TCAM and CAM memory usage inside networking devices
- How can router decide so fast?
- INE v5 Full-Scale Practice Lab1 TS GNS3 topology
- INE R&Sv5 Workbook Full-Scale Practice Lab1 made in GNS3
- BGP dampening – punishment for unstable BGP prefixes
- Source-based routing in IPv4 and IPv6 networks
- BGP communities
- Troubleshooting EIGRP Neighbor Relationships
- GNS3 topology for INE Workbook
- Administrative Distance for Static Route is 1 or 0?
- IPv6 RA Router Advertisement and all the flags inside
- What is static floating route
- Pathping more than handy network troubleshooting tool
- BGP – Border Gateway Protocol
- Dynamic Routing Protocols
- Routers hardware – How are the Routers made?
- Routing – How are routers working?
- Routing – Static and Dynamic routes – What is route?
Switching – How it works?
- Link Aggregation – LACP Protocol
- WoL – Wake On LAN
- How to Enable Dot1x – more complex setup for wired network
- How to Enable Dot1x authentication for wired clients
- What is a non-blocking switch?
- HOL Head-of-line blocking
- TCAM and CAM memory usage inside networking devices
- VXLAN – Virtual Extensible LAN
- What is Jitter in Networking?
- Unidirectional communication filter between two VLANs
- Routing between VLANs
- Trunking Methods – VLAN Identification methods across multiple switches
- VLANs – Trunk and Access link types
- Static vs Dynamic VLANs
- VLAN – What are VLANs?
- VLAN Security – Main VLAN reason
- VLANs controling broadcast propagation
- Why we need VLANs, an Introduction to VLAN technology
- PVLAN – Private VLANs
Security
- Reflexive Access List
- Juniper Control Plane Protection
- QKD – How Quantum Cryptography Key Distribution Works
- Introduction to Quantum Cryptography
- Cryptography
- Control Plane Protection in Cisco IOS
- How Encryption of Network Traffic Works?
- Mitigate DoS Attack using TCP Intercept on Cisco Router
- How to Enable Dot1x – more complex setup for wired network
- How to Enable Dot1x authentication for wired clients
- What is the difference between tunnel | transport mode in IPsec
- Source-based routing in IPv4 and IPv6 networks
- IPv6 First-Hop Security
- RADIUS server Infrastructure
- Find unknown static IP on device
- Unidirectional communication filter between two VLANs
- How to prevent or stop DoS attacks?
- DoS Methods – PDoS, Permanent DoS attacks
- DoS Methods – ICMP and SYN flood, Teardrop and Low-rate DoS attacks
- DDoS – Distributed Denial of Service attack
- DoS and DDoS – Denial of Service attacks
- IPSec
- Application Layer Firewalls
- Transparent Firewalls
- How does Firewall defend our Network?
- Protecting a VoIP Network with Security Appliances
- Implement Auxiliary VLANs to make VoIP Networks secure
- Make voice Network more secure
- Flame Virus
- Vishing and Toll Fraud – VoIP Vulnerability
- Attack on SIP protocol – VoIP Vulnerability
- VoIP spam – VoIP Vulnerability
- VoIP Security – Main Targets of VoIP Attacks
- Firewall – Defending Networks
- Secure the switch – best steps
- VACL – VLAN Access Lists
- Switch Security Attacks – Layer 2 Security
- VPN – What is VPN and how it works?
- Phishing – What is phishing?
- Configuring MACsec Encryption
- MACSec – Media Access Control Security
- Secure the switch – best steps
- PVLAN – Private VLANs
- SPAN – Switched Port Analyzer technology and configuration
- Prevent ARP Spoofing using Dynamic ARP Inspection – DAI
- Spoofing Attacks – ARP Spoofing
- Prevent DHCP Server Spoofing by using DHCP snooping
- Protecting Against STP Layer 2 Attack
- STP Layer 2 attack – Manipulating Spanning Tree Protocol settings
- Mitigate VLAN hopping attack – Get rid of Layer 2 attacks
- VLAN hopping attack – Switch Spoofing and Double tagging
- Using Port Security to Mitigate Layer 2 Attacks
- Telnet Attacks – Ways to compromise remote connection
- CDP Attacks – Cisco Discovery Protocol Attack
- Spoofing Attacks – DHCP Server Spoofing
- MAC Address Flooding – MAC address table overflow attacks
- Switch Security Attacks – Layer 2 Security
Network Fundamentals:
- What is route recursion
- Proxy and Reverse Proxy Server
- Wildcard mask – What’s the difference from subnet mask?
- What is internet – How does the internet work and why is so important?
- How We Open a Web Page and What is Going on Behind?
- Network – Computer network
- IPv6 Day – 6 June 2012.
- Network – More news about way it works
- VoIP and IP telephony – Defining Basics of Voice
- Routing – How are routers working?
- IP Address – Internet Protocol address: Basic about IPv4
- Routing – Static and Dynamic routes – What is route?
- LAN – Local Area Network
- Collisions and collision detection – What are collisions in Ethernet?
- Data Packet – IP Packet – What is this packet story all about?
- MAC address (MAC L2 addressing) – What is this physical addressing?
- WAN – Wide Area Network
- What is my IP address
About Protocols:
- BGP dampening – punishment for unstable BGP prefixes
- Port Numbers – How does Transport layer identifies the Conversations
- Dynamic Routing Protocols
- OSI model – Get to know networking with 7 layer model
- What is a protocol?
- Voice protocols – VoIP protocols
- PNRP Name Resolution – How it works?
- IPSec
- TCP and UDP port numbers – complete list
Scientific & Academic Work
- You Know How Networks Work, Want To Know How Everything Else Works? Here’s Some Books
- The Use of Graph Database in Network Complexity Analysis
- QKD – How Quantum Cryptography Key Distribution Works
- Introduction to Quantum Cryptography
- Cryptography
- SDN SOFTWARE DEFINED NETWORKS: AN OVERVIEW
- COGNITIVE NETWORKS THE NETWORKS OF THE FUTURE
IPv6:
- IPv6 Generated with EUI-64 Has a Strange Bit Inside
- The New Way of Generating IPv6 – SLAAC EUI-64 Address Format
- Solicited-node multicast address
- Source-based routing in IPv4 and IPv6 networks
- IPv6 First-Hop Security
- IPv6 Implementation beyond theory & How playing with RA messages may be issue-istic
- IPv6 RA Router Advertisement and all the flags inside
- IPv6 addresses – What is IPv6?
- IPv6 – SLAAC Stateless Address Autoconfiguration
- IPv6 – SLAAC EUI-64 Address Format
- NDP – Neighbor Discovery Protocol
- What’s that % sign after ipconfig IPv6 address?
- IPv6 Day – 6 June 2012.
Configurations:
- Check Point Firewall VM Disk Resize
- Create or Edit a File on Cisco IOS Flash
- Cisco Catalyst Stack Upgrade
- Missing good old ‘wr’ command on N9K? let’s bring it back!
- Juniper SRX Cluster Failover Tuning
- Reflexive Access List
- Juniper Control Plane Protection
- How to Clear Entire Configuration of your Juniper Device
- Enable Source-Specific Multicast in Iperf
- Source-Specific Multicast Configuration
- Cisco Catalyst 6880-X VSS ISSU Upgrade Steps
- ISSU Upgrade of Cisco Catalyst 6880-X VSS Cluster and 6800ia FEX extenders
- TFTP via VRF
- Control Plane Protection in Cisco IOS
- Mitigate DoS Attack using TCP Intercept on Cisco Router
- How to Enable Dot1x – more complex setup for wired network
- How to Enable Dot1x authentication for wired clients
- INE v5 Full-Scale Practice Lab1 TS GNS3 topology
- When they throw a Cisco guy to do something with HP networking gear
- INE R&Sv5 Workbook Full-Scale Practice Lab1 made in GNS3
- BGP dampening – punishment for unstable BGP prefixes
- GNS3 topology for INE Workbook
- PBR – Policy-based Routing configuration example
- When I connect to device with telnet or SSH I don’t see logging?
- Saving Router Configuration to Server
- Use TFTP to configure a Router
- Saving VLAN.dat To NVRam
- PVLAN configuration
- Configuring LLDP – Link Layer Discovery Protocol
- How to configure CDP – Cisco Discovery Protocol
- About Cisco IOS and Juniper JUNOS
- Command Modes – Cisco IOS – Juniper Junos
- SPAN – Switched Port Analyzer technology and configuration
- Basic Cisco and Juniper router Configuration
- Creating Command Aliases – Be faster in IOS typing
- Telnet and SSH – Remotely connect to device using Telnet and SSH
- Mitigate VLAN hopping attack – Get rid of Layer 2 attacks
- Automatic router backup to FTP server – How to configure?
- Cisco Switch password recovery – Catalyst Fixed Configuration Switches
- Protecting Against STP Layer 2 Attack
- Manage Router’s ARP Cache
- Using Port Security to Mitigate Layer 2 Attacks
- Prevent DHCP Server Spoofing by using DHCP snooping
- Prevent ARP Spoofing using Dynamic ARP Inspection – DAI
Tunneling Protocols:
- What is the difference between tunnel | transport mode in IPsec
- VXLAN – Virtual Extensible LAN
- L2TP – Layer 2 Tunneling Protocol
- VPN – What is VPN and how it works?
Network Devices and Equipment:
- Cisco Catalyst 6880-X VSS ISSU Upgrade Steps
- ISSU Upgrade of Cisco Catalyst 6880-X VSS Cluster and 6800ia FEX extenders
- TFTP via VRF
- How to generate network packets – Ostinato Packet/Traffic Generator
- TCAM and CAM memory usage inside networking devices
- Cisco VIRL is finally out
- Redundant Default Gateway solutions in IPv4 networks
- Cisco VIRL – Virtual Internet Routing Lab
- Find unknown static IP on device
- Router – What is a router?
- Routers hardware – How are the Routers made?
- VoIP Network Components
- Switch & Hub – What are they and what is the difference?
- Host – When the Host is Client and when Server?
- Recovery From Corrupt or Missing Software Image on Cisco device
- Server – What is a server and how it works?
- NIC – Network Interface Card
- About Cisco – What is Cisco exactly
- About Juniper – What is Juniper exactly
- UTP Cables – Unshielded Twisted Pair Cable
- Optical Fiber – Fiber Optics
- Backbone – What is backbone?
- Network Downtime Is Expensive – Time is Money
- Cisco EnergyWise – New way to save energy
VoIP – Voice technology:
- What is Jitter in Networking?
- Voice protocols – VoIP protocols
- VoIP Network Components
- VoIP and IP telephony – Defining Basics of Voice
- VoIP Security – Main Targets of VoIP Attacks
- VoIP spam – VoIP Vulnerability
- Vishing and Toll Fraud – VoIP Vulnerability
- Attack on SIP protocol – VoIP Vulnerability
- Make voice Network more secure
- Implement Auxiliary VLANs to make VoIP Networks secure
- Protecting a VoIP Network with Security Appliances
OSI layers:
7. Application layer:
- BGP – Border Gateway Protocol
- DHCP – Dynamic Host Configuration Protocol
- DNS – Domain Name System
- FTP – File Transfer Protocol
- Gopher
- HTTP – Hypertext Transfer Protocol – What is HTTP Protocol used for?
- IMAP – Internet Message Access Protocol
- IRC – Internet Relay Chat Protocol
- LDAP – Lightweight Directory Access Protocol
- Netconf
- NNTP – Network News Transfer Protocol
- NTP – Network Time Protocol
- PNRP the New DNS – Peer Name Resolution Protocol
- POP – Post Office Protocol
- RPC – Remote Procedure Call
- RTP – Real-time Transport Protocol
- SIP – Session Initiation Protocol
- SMPP – Short Message Peer-to-Peer
- SMTP – Simple Mail Transfer Protocol
- SPDY – reducing web page load time protocol
- SSI – Simple Sensor Interface protocol
- XMPP – Extensible Messaging & Presence Protocol
6. Presentation layer:
5. Session layer:
4. Transport layer:
- Static Route Load Balance
- Nagle’s algorithm
- MPTCP – Multipath TCP
- DCCP – Datagram Congestion Control Protocol
- Port Numbers – How does Transport layer identifies the Conversations
- UDP – User Datagram Protocol
- TCP – Transmission Control Protocol
- TCP and UDP port numbers – complete list
3. Network layer:
- Static Route Load Balance
- BGP communities
- VXLAN – Virtual Extensible LAN
- Redundant Default Gateway solutions in IPv4 networks
- ICMP – Internet Control Message Protocol
- IPv6 Anycast Address type
2. Data link layer:
- IPv6 Generated with EUI-64 Has a Strange Bit Inside
- Link Aggregation – LACP Protocol
- MACSec – Media Access Control Security
- Proxy ARP
- L2TP – Layer 2 Tunneling Protocol
- ISL Inter-Switch Link Protocol – Trunking or Frame Tagging protocol
- LLDP – Link Layer Discovery Protocol
- CDP – Cisco Discovery Protocol
- NDP – Neighbor Discovery Protocol
1. Physical layer: