This article was previously published under Q222102
This article has been archived. It is offered "as is" and will no longer be updated.
This article describes prioritization of network traffic using IP precedence.
IP Precedence provides the ability to classify network packets at Layer 3, analogous to the functionality of the 802.1P protocol at Layer 2. With IP Precedence configured, network packets traverse IP Precedence devices according to the priority you set. Priority traffic is always serviced before traditional traffic.
IP Precedence is considered the best effort Quality of Service at layer 3. Packets are prioritized and then queued accordingly to traverse the network. IP Precedence was designed in IPv4 by the IETF. It uses 3 bits of the 8-bit Type of Service (TOS) field of an IP header. There are 8 classes of services in IP Precedence. The classification range is 0-7 where 0 (zero) is the lowest and 7 is the highest priority.
You can set IP Precedence for packet prioritization using Quality of Service enabled programs, computers, routers, or layer 3 switches.
You can use IP Precedence in conjunction with the 802.1p protocol and RSVP signaling.