A network diagnostic component that is placed in-line between a first and second node. The diagnostic component is used to perform a comparison operation on any specified portion of a network data frame. For example, the first node may communicate with the second node using a network data frame that includes one or more data units. The network diagnostic component uses a starting and ending address that specify where in the network data frame to begin and end the comparison operation. A match template that specifies a particular condition for comparison is also used. The network diagnostic component then performs the comparison operation by searching for a data unit that at least partially matches the comparison condition in the portion of the network data frame specified by the starting and ending addresses. The data unit may be located at any location in the specified portion of the data frame.