Distance-vector routing protocol is one of the two major classes of routing protocols used in packet-switched networks for computer communications, the other major class being the link-state protocol. A routing protocol is a protocol that specifies how routers communicate with each other to disseminate information that allows them to select routes between any two nodes on a network. In telecommunication, a store-and-forward switching center is a message switching center in which a message is accepted from the originating user, i.e., sender, when it is offered, held in a physical storage, and forwarded to the destination user, i.e., receiver, in accordance with the priority placed upon the message by the originating user and the availability of an outgoing channel. A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires.

Distance Vector vs. Link State Protocols
Distance-vector routing protocol is one of the two major classes of routing protocols used in packet-switched networks for computer communications, the other major class being the link-state protocol. A distance-vector routing protocol uses the Bellman-Ford algorithm to calculate paths. A link-state routing protocol is one of the two main classes of routing protocols used in packet-switched networks for computer communications.

Routed vs. Routing Protocols
A routing protocol is a protocol that specifies how routers communicate with each other to disseminate information that allows them to select routes between any two nodes on a network. Routed Protocols are layer 3 Network Layer protocols. They include Internet Protocol (IP), Internetwork Packet Exchange (IPX) and Apple's AppleTalk. Routed or routable protocols allow for internetwork communication by assigning network and host identities to packets, without routed protocols network communication would be restricted to the local segment. Routing protocols serve a different purpose. Instead of being used to send data between source and destination hosts, a routing protocol is used by routers to exchange routing information with one another. Routing Protocols are protocols that enable routers to communicate with one another in order to maintain their routing tables. These routing tables help them deliver routed protocols across networks.

Classful vs. Classless Protocols
Classful networking is the name given to the first round of changes to the structure of the IP address in IPv4. Originally, the 32-bit IPv4 address consisted simply of an 8-bit network number field (which specified the particular network a host was attached to), and a rest field, which gave the address of the host within that network. This format was picked before the advent of local area networks (LANs), when there were only a few, large, networks such as the ARPANET.

Store-and-Forward Switching
In telecommunication, a store-and-forward switching center is a message switching center in which a message is accepted from the originating user, i.e., sender, when it is offered, held in a physical storage, and forwarded to the destination user, i.e., receiver, in accordance with the priority placed upon the message by the originating user and the availability of an outgoing channel.  A technique commonly used in messaging services where a data transmission is sent from one device to a receiving device but first passes through a "message center". The message center is typically a server that is used by the message service to store the transmitted message only until the receiving device can be located, and it then forwards the transmission to the intended recipient and deletes the message from the server. A common type of store-and-forward messaging is that used between mobile phones.

"Store and forward is a technique common in messaging services where a data transmission is sent from one device to a receiving device but first passes through a "message center". The message center is typically a server that is used by the message service to store the transmitted message only until the receiving device can be located, and it then forwards the transmission to the intended recipient and deletes the message from the server." -- Webopedia.

Cut-Through Switching
In computer networking, cut-through switching is a switching method for packet switching systems, wherein the switch starts forwarding a frame before the whole frame has been received, normally as soon as the destination address is processed. This technique reduces latency through the switch, but decreases reliability.

Fragment-Free Switching
Fragment free is a switch forwarding method. Fragment free will ensure that enough bytes are read from the source to detect a collision before forwarding. This is only useful if there is a chance of a collision on the source port - so a fully switched network may not benefit from fragment free in comparison to low latency cut through switching. Frames are forwarded before any checksums can be calculated. Fragment-free switching, also known as runtless switching, is a hybrid of cut-through and store-and-forward switching. Fragment-free switching was developed to solve the late-collision problem. Fragment-free switching is suitable for backbone applications in a congested network, or when connections are allocated to a number of users. The switching device checks the source and destination MAC address of a packet, and sends the packet to the port corresponding to the destination.

V-Lan
A virtual LAN, commonly known as a VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the same wire, regardless of their physical location. A VLAN has the same attributes as a physical LAN, but it allows for end stations to be grouped together even if they are not located on the same LAN segment. Network reconfiguration can be done through software instead of physically relocating devices. Virtual LANs (VLANs) can be viewed as a group of devices on different physical LAN segments which can communicate with each other as if they were all on the same physical LAN segment. VLANs provide a number of benefits over the network described. Switches using VLANs create the same division of the network into separate broadcast domains but do not have the latency problems of a router. Switches are also a more cost-effective solution.

_{V-Lan Benefits:}

• Increased performance
• Improved manageability
• Network tuning and simplification of software configurations
• Physical topology independence
• Increased security options

Virtual Private Network (VPN)
A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The link-layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features. Basically, a VPN is a private network that uses a public network (usually the Internet) to connect remote sites or users together. Instead of using a dedicated, real-world connection such as leased line, a VPN uses "virtual" connections routed through the Internet from the company's private network to the remote site or employee. Virtual private networks help distant team members work together, much like desktop sharing.

References
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