Class-based queuing (CBQ) is a

queuing discipline A network scheduler, also called packet scheduler, queueing discipline (qdisc) or queueing algorithm, is an arbiter on a node in a packet switching communication network. It manages the sequence of network packets in the transmit and receive q ...

for the

network scheduler A network scheduler, also called packet scheduler, queueing discipline (qdisc) or queueing algorithm, is an arbiter on a node in a packet switching communication network. It manages the sequence of network packets in the transmit and receive q ...

that allows traffic to share

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

equally, after being grouped by classes. The classes can be based upon a variety of parameters, such as priority, interface, or originating program. CBQ is a traffic management algorithm developed by the Network Research Group at Lawrence Berkeley National Laboratory as an alternative to traditional router-based technology. Now in the public domain as an open technology, CBQ is deployed by companies at the boundary of their WANs. CBQ divides user traffic into a hierarchy of classes based on any combination of IP addresses, protocols and application types. A company's accounting department, for example, may not need the same Internet access privileges as the engineering department. Because every company is organized differently and has different policies and business requirements, it is vital for traffic management technology to provide flexibility and granularity in classifying traffic flows. CBQ lets network managers classify traffic in a multilevel hierarchy. For instance, some companies may first identify the overall needs of each department or business group, and then define the requirements of each application or group of applications within each department. For performance and architectural reasons, traditional router-based queuing schemes are limited to a small number of classes and only allow one-dimensional classification. Because it operates at the IP network layer, CBQ provides the same benefits across any

Layer 2 The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer pr ...

technology and is equally effective with any IP protocol, such as

Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly ...

(TCP) and

User Datagram Protocol In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. ...

(UDP). It also operates with any client or server TCP/IP stack variation, since it takes advantage of standard TCP/IP flow control mechanisms to control end-to-end traffic. An implementation is available under the

GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the Four Freedoms (Free software), four freedoms to run, study, share, and modify the software. The license was th ...

for the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...

References

Computer networking Network scheduling algorithms {{Compu-network-stub