receivedDSByteCheck

Used in DScondition

Syntax: cis, single

Description: Specifies a condition for traffic based on the contents of the differentiated services (DS) byte of the received packet's IP header. The format is a string of the form xxxxxxxx:xxxxxxxx, where x is 0 or 1. The left substring is a Mask, and the right substring a Match. The DS byte of the received packet's IP header is ANDed with Mask, and the result is compared against Match. Therefore, the condition can be expressed as follows:

(receivedPacketTOSbyte & Mask == Match)?

where & indicates the bitwise AND operation, and == the bitwise compare operation.

The combination of Mask and Match makes it possible to define DS byte-based profiles where certain bits in the DS byte may be ignored for the purpose of comparison.