Assigning an 802.1p priority to IPv4 packets on the basis of the ToS precedence bits

If a device or application upstream of the switch sets the precedence bits in the ToS byte of IPv4 packets, you can use this feature to apply that setting for prioritizing packets for outbound port queues. If the outbound packets are in a tagged VLAN, this priority is carried as an 802.1p value to the adjacent downstream devices.


qos type-of-service ip-precedence

Causes the switch to automatically assign an 802.1p priority to all IPv4 packets by computing each packet’s 802.1p priority from the precedence bits the packet carries. This priority determines the packet’s queue in the outbound port to which it is sent. If the packet leaves the switch on a tagged port, it carries the 802.1p priority with it to the next downstream device.

(ToS IP Precedence Default: Disabled)

no qos type-of-service

Disables all ToS classifier operation, including prioritization using the precedence bits.

show qos type-of-service

When the IP-precedence mode is enabled (or if neither ToS option is configured), this command displays the ToS configuration status. If the Diff-serv mode is enabled, codepoint data is displayed.

Using the IP-precedence classifier, prioritization of outbound packets relies on the IP-Precedence bit setting that IP packets carry with them from upstream devices and applications. To configure and verify this option:
Figure 28: Enabling ToS IP-precedence prioritization

To replace this option with the ToS diff-services option, configure diff-services as described below, which automatically disables IP-Precedence. To disable IP-Precedence without enabling the diff-services option, use this command: no qos type-of-service