Investigating the Delay Impact of the DiffServ Code Point (DSCP)

The DiffServ Code Point (DSCP) field in the IP header allows to specify a desired per-hop behavior as packets traverse routers. Setting the DSCP field opportunistically, without prior contractual agreement, has recently become accepted practice for Internet end hosts. Measurement studies find that there is reason to hope for a DSCP setting to have an effect on traffic, and at least configuring this value is not heavily detrimental: systematic drops of packets due to non-zero DSCP values are rare, and the value is often left intact along an end-to-end path. What these studies do not discuss is whether per-hop behaviors truly are honored: what happens to packets in terms of the delay they experience? In this paper, we make an attempt to find a first answer to this by mining a dataset of our own recent large-scale measurement study. Using a deep neural network, we obtain the importance of the factors which help us understand the delay impact of the DSCP.