In Software Defined Networking, in order for the phys- ically distributed controllers to act as a logically cen- tralized controller, state consistency has to be guaran- teed. Using an in-band approach, e.g., synchronization control traffic interleaving with data traffic, has the ad- vantage to have lower deployment cost. However, the potential impact of such traffic mixture is still unknown to network operation. This paper is a start point to explore such deployment scenario by investigating the characteristic of in-band control traffic.