ToS

Referring to a field in the Internet Protocol version 4 (IPv4) header that indicates the quality of service (QoS) requested for the datagram. Although TCP/IP networks currently do not provide guaranteed QoS, the networks will attempt to honor QoS requests in terms of parameters that include packet precedence (i.e., priority), low delay, high throughput, and high reliability. See also datagram, DiffServ, header, IPv4, QoS, and TCP/IP.