The OSI Physical Layer
The Physical layer (OSI layer 1) deals with the mechanical and electrical specifications of the network hardware. Layer 1 specifications define connectors, pin-outs, signal voltages, and related software. More ...
Network Operating Systems
The purpose of a network is to permit users share resources located on other computers and to share peripheral devices such as printers. A network operating system (NOS) is specialized systems software designed to provide networking functionality. More ...
Neighbor Discovery Protocol (NDP)
Neighbor Discovery Protocol is part of the new version of the Internet Protocol (IPv6). Its function is to resolve IPv6 addresses into valid MAC addresses. All addresses discovered by NDR are stored in a buffer known as the neighbor cache. More ...
Understanding IP Routing
The Transmission Control Protocol/Internet Protocol TCP/IP suite of protocols is the underlying technology for information exchange on the Internet. This essential reference shows you how to isolate and resolve common network failures and to sustain optimal network operation. More ...
Session Border Controllers - More Than Just a Voice Firewall
The migration from Time-Division Multiplexing to the more flexible IP based SIP networks brought an unexpected security challenge. Session Border Controllers focused primarily on SIP and H.323 session security. More ...
Video - Introducing the OSI Model
This video by Kevin Wallace introduces the OSI networking model. More ...
Free eBook: IPv6 Addressing
All the IPv4 addresses are quickly being used up. The conversion to IPv6 is now underway. In this free eBook, Aaron Balchunas describes IPv6 and how to configure it to work along side IPv4. Learn which protocols will need to be updated to work with IPv6. Learn how to configure IPv6. More ...
Wireless Standards - 802.11a 802.11b 802.11g 802.11n 802.11i Explained
The IEEE 802.11 family of standards which provides for Wireless Ethernet or (Wi-Fi) has evolved over the years. This article explains the differences between 802.11a 802.11b 802.11g 802.11n and 802.11i. More ...
What Are Private IP Addresses?
Normally you have to be assigned an IP address, or a group of IP addresses by a Regional Internet Registry. However, if you just need IP addresses for an internal network that will not be routed to the Internet, you can select from blocks of IP addresses reserved as Private IP addresses. More ...
The TCP/IP protocol Datagram Format
A datagram is the packet format defined by the Internet Protocol. A pictorial representation of an IP datagram shows the first five or six 32-bit words of the datagram are control information called the header. More ...
Internet Security and VPN Network Design
This article discusses some essential technical concepts associated with a VPN. A Virtual Private Network (VPN) integrates remote employees, company offices, and business partners using the Internet and secures encrypted tunnels between locations. More ...
Looking at the OSI 7 Layer Reference Model
The OSI (Open Systems Interconnection) model is a 7 layer reference model for how applications can communicate over a network. Don't confuse The OSI model with TCP/IP Protocol which has 4 layers and is the actual architecture used for networking. More ...
WAN Network Protocols - DSL, SONET, HDLC, DWDM, DLSW+
This article discusses some of the most implemented Wide Area Networking (WAN) protocols in enterprise networking environments today including HDLC, DSL, SONET, DWDM, and DLSW+. HDLC is a Cisco proprietary protocol for designed for sending data across serial links. More ...
Comparing IPv4 and IPv6 at a Glance
When examining the details of the IPv4 and IPv6 headers, there are some important differences between the two protocols. This article summarizes some of the differences. More ...
The OSI Reference Model
No real world network operating systems conform exactly to the OSI model, but it is useful as a reference when describing existing systems. It is difficult to study network devices such as routers, switches, and gateways without using the model. More ...
