next up previous
Next: Virtual Network Configuration Implementation Up: Virtual Network Configuration for Previous: Time Warp Emulation

Virtual Network Configuration Overview

The Virtual Network Configuration (VNC) algorithm can be explained by an example. A remote node's direction, velocity, bandwidth used, number of connections, past history and other factors can be used to approximate a new configuration sometime into the future. All actual configuration processes can begin to work ahead in time to where the remote node is expected to be at some point in the future. If the prediction is incorrect, but not far off, only some processing will have to be rolled back in time. For example, the beamsteering process results may have to be adjusted, but the topology and many higher level requirements will still be correct. This working ahead and rolling back to adjust for error with reality can be a continuous process, depending on the tradoff between allowable risk and amount of processing time allowed into the future.

As a specific example, consider the effects of handoff on TCP performance as described in [10]. In this work, throughputs were measured in Table 10.

  table212
Table 10:   Bandwith Loss Due to Handoff.

Even a zero second delay in receiving handoff notification caused significant performance loss. In the Virtual Network Configuration System, the handoff will be precomputed which should result in performance at least as good as that shown for overlapping cells in [10].



Steve Bush
Mon Aug 26 18:24:40 CDT 1996