DiffServ for differentiated reliability in meshed IP/WDM networks

The protection of service delivery in an integrated network is fast becoming a critical issue. In previous work, we proposed two protection methods, DiffServ and DiffProtect and examined, on a small network, whether DiffServ can be used as a protection mechanism against failures in IP/WDM networks. The results showed that, on average, DiffServ can provide better QoS guarantees than its optical counterpart, DiffProtect. We also found that DiffProtect may perform better than DiffServ under some extreme failure situations so that DiffServ cannot totally replace optical protection in a network but might be able to do so to some degree. We extend these results to larger networks and more complex combinations of protection techniques. We study in this paper a 4-node linear topology and a small 6-node mesh network which can be protected by DiffServ, DiffProtect or even a combination of both (MixProtect). Results show that replacing optical protection by DiffServ cannot be done randomly and that the number and position of links protected by DiffServ versus DiffProtect must be carefully chosen in order to guarantee adequate performance to all traffic types. We explain how this can be achieved with current technology. We also show that the cost of protection using DiffServ is significantly less than that of current methods.