L2TP (Layer 2 Tunneling Protocol) - Published in 1999 as proposed standard RFC 2661, L2TP has its origins primarily in two older tunneling protocols for PPP: Cisco's Layer 2 Forwarding (L2F) and Microsoft's Point-to-Point Tunneling Protocol (PPTP). A new version of this protocol, L2TPv3, was published as proposed standard RFC 3931 in 2005. L2TPv3 provides additional security features, improved encapsulation, and the ability to carry data links other than simply PPP over an IP network (e.g., Frame Relay, Ethernet, ATM, etc). L2TP acts as a data link layer (layer 2 of the OSI model) protocol for tunneling network traffic between two peers over an existing network (usually the Internet). It is common to carry Point-to-Point Protocol (PPP) sessions within an L2TP tunnel. L2TP does not provide confidentiality or strong authentication by itself. IPsec is often used to secure L2TP packets by providing confidentiality, authentication and integrity. The combination of these two protocols is generally known as L2TP/IPsec.
LAN (Local Area Network) - A computer network that spans a relatively small area and typically offers high-speed communications. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines, coaxial cable, wi-fi, etc. A system of LANs connected in this way is called a wide area network (WAN). Most LANS of today utilize Ethernet and/or Wi-Fi connections.
LDAP (Lightweight Directory Access Protocol) - A protocol used to access listings in hierarchical information directories (databases). LDAP is a simplified version of the standard used to gain access to X.500 directories. Microsoft's Active Directory which was first released in Windows 2000 utilizes LDAP for locating records in the directory.
Link State Routing Protocols – are one of the two main classes of routing protocols used in packet switching networks and includes protocols such as Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS). The link-state protocol is performed on every router on the network, where every routing node constructs a map of the connectivity to the network by showing which nodes are connected to each other. Each router calculates the next best logical hop from it to every possible known destination which forms the node's routing table.
Lithium-Ion - Lithium-ion rechargeable batteries generally provide more energy capacity than nickel based types of the same weight. They also do not suffer from "memory effect" and are non-toxic. These batteries are used in many devices including laptops, cell phones, and digital cameras.
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LAN (Local Area Network) - A computer network that spans a relatively small area and typically offers high-speed communications. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines, coaxial cable, wi-fi, etc. A system of LANs connected in this way is called a wide area network (WAN). Most LANS of today utilize Ethernet and/or Wi-Fi connections.