Experimental Results On Data Transfers Over Dedicated Channels

We describe experimental results on large data transfers and stable control streams over a dedicated 1Gbps channel of several hundred miles length implemented over ORNLAtlanta production OC192 link. To support file transfers at 1Gbps rates, the end hosts are equipped with SCSI hard drives in a RAID 0 configuration and dedicated NICs, which are directly connected to the router. The 1Gbps channel is provisioned by configuring routers using the filterbased forwarding mechanism to implement an IP loop-back over the OC192 link. The performance profile generated from traffic measurements on the channel indicates nonzero packet losses and non-trivial jitter levels, both of which must be accounted for by the transport protocols to ensure high throughput and robust performance. We developed a UDP-based transport protocol by leveraging existing methods to achieve close to 100 percent channel utilization for file and data transfers. We also tested an existing protocol for implementing stable control streams over this channel. These results provide valuable insights into both the channel and host aspects of supporting data transfers over ded-