Resource Library

The OSI model is a conceptual tool used to discuss and describe network functions. The use of a standard reference model is essential to communicating ideas as well as creating new technologies. It is a good idea to be familiar with the OSI model, the features assigned to each layer, and examples of common protocols or technologies associated with the OSI layers.

A local area network (LAN) provides a path of communication, allowing the delivery of packets of data, voice, or video originating from the sender (logical source address) to the receiver (logical destination address). Ethernet is the most common LAN used. As you start to learn about networking, remember that communication and the movement of large numbers, whether it is people, cars, mail, or network traffic, have a commonality. Everything you know and use in your daily life can be compared to the way traffic moves.

Session Initiation Protocol (SIP) is an internet signaling protocol, developed by the IETF (starting in 1996), for establishing, maintaining, and tearing down sessions between a variety of real-time media, including voice, video, and chat. SIP allows endpoints to locate other endpoints, whether stationary or mobile. SIP doesn't have to worry about transporting voice or video as Real Time Transport Protocol (RTP) takes care of that. It also relies on Session Description Protocol (SDP) to negotiate capabilities and codecs. SIP does not provide a Directory Service or Authentication, but it does work with services such as LDAP or RADIUS. SIP is only concerned with signaling. This white paper is going to look at the way SIP is used in the converged Unified Communications environment.

Meet Global Knowledge course director and lab topology architect Joey DeWiele, a specialist in Unified Communications. Joey will walk you through the benefits of our exclusive Cisco UC lab architecture - a more scalable and stable approach to the all-important labs featured in unified communications courses. Our labs feature upgraded hardware and software including Custom Lenovo T61 PCs, 7965 IP Phones, 3560 Switches and Call Manager 7. With our flexible UC architecture, students are able to view and experience the full lab architecture regardless of which Cisco UC course they are taking or the skill set they are seeking. The lab architecture features a realistic network with redundant environments that are made rich with multiple machines, pre-deployed tools with shortcuts, online documentation that is particular to individual pods, and multiple OS support for all virtual machines (Windows, Linux, VMware).

John Barnes, Global Knowledge's Cisco Course Developer, discusses enhancements to our UCS Troubleshooting Boot Camp and suggestions for students in preparation for this course.

Global Knowledge Product Manager Tori Easterly discusses the benefits of our Understanding Networking Fundamentals course.

Multiplexing is the technology that is able to combine multiple communication signals together in order for them to traverse an otherwise single signal communication medium simultaneously. Multiplexing can be applied to both analog and digital signals. A benefit of using multiplexing, or muxing, is reducing the physical hardware cost for expensive dedicated network communication segments, such as copper or fiber cables.

Are you at a crossroads professionally or looking to start training for a new job? If so, you might want to consider pursuing network administration as a career. Network administrators are responsible for maintaining computer hardware and software systems that make up a computer network, including maintaining and monitoring active data networks, converged infrastructure networks, and related network equipment.

The driver behind 802.11n is MIMO, or multiple input multiple output. This video explains how MIMO works to double your channel speed by sending two or more data streams over the same channel.

Answer? When it is flagged as a retransmission in Wireshark!