What’s a server message block?

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SMB/CIFS is a protocol used for sharing files, ports, and printers on computer networks. It allows inter-process communication and is client-driven. SMB is comparable in speed to other protocols on LANs but has latency issues on WANs. It also increases broadcast traffic, causing delays and packet loss.

A server message block (SMB), also known as the Common Internet File System (CIFS), is a protocol used on computer networks that allows users to share access to files, ports, and printers on the system, facilitating communication between people connected to the same network. It also provides an inter-process communication platform, which allows processes to exchange threads of data with each other while they are running. A server message block is a client-side approach to network communications, meaning that everything that happens on the network is driven by requests from individual client computers.

In a client-side configuration, while all computers on the network are connected to one master “server” computer, that server computer assumes a mostly passive role. When things on the network are running normally, the server will not act until requests are made from individual client computers, such as a request to access a shared file stored on the server’s drive or a request to pipe information from the network computer A to network computer B. At all other times when the server is not under the direct control of an end user, it simply waits for orders to arrive.

On local area networks (LANs), server message block communication is generally considered to be comparable in speed to other standard protocols for passing data. Over wide area area networks (WANs), such as the Internet, latency has a substantial effect on server message block communications compared to competing types of file transport protocols, such as File Transport Protocol (FTP). Latency is simply the time it takes for a communication to take place, usually measured in milliseconds. Lower latency provides a feeling of less “lag” when sending information, increasing the smoothness of information transfer.

Furthermore, even on local area networks, SMB communication results in a substantial increase in broadcast traffic. This traffic originates indirectly through the NetBIOS protocol on the system, because the server’s message blocking system itself produces no broadcasts. An increase in broadcast traffic can clutter the network, resulting in delays and an increased likelihood that packets will be lost as they travel through the network. For this reason, SMB communications are generally not preferred on networks with large numbers of users, where the problem is more likely to be exacerbated by volume.




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