A cross-layer design for large transfers in SDNs

Software Defined Network (SDN) technologies have enabled the introduction of new services such as dynamic Layer-1 (L1) circuits and Layer-2 (L2) virtual circuits (VCs). This work presents a cross-layer design that leverages transport- and link-layer protocols to enable the full use of high-rate circuits/VCs to achieve high-throughput transfers. Three cases are considered: (i) single circuit/rate-guaranteed VC for a single large transfer from a server, (ii) multiple simultaneous large transfers from a server, and (iii) semi-rate-guaranteed VC. Circuit TCP (CTCP) and the Token Bucket Filter (TBF) queueing discipline of the Linux traffic control (tc) utility are recommended for the first case, and parameter selection methods are provided. For the second case, the tc Hierarchical Token Bucket (HTB) discipline is recommended as it supports dynamic additions and deletions of classes without impact on ongoing large-transfer flows using existing classes. For the third case, CTCP is recommended if the large-transfer throughput is the primary concern, while HTCP is recommended if higher consideration is given to other flows.