Abstract: A transition protocol is provided herein in which a first rule set for routing packets received by a group of switches during a first time period is to be updated to a second rule set. During a transition period, at least some switches in the group of switches route packets to a controller, while other switches in the group of switches route packets to a next hop that is unchanged by the change in the rule set. The controller forwards packets that are received from at least some of the switches in the group to a destination node each of the packets, as determined from the updated rule set.

Abstract: A transition protocol is provided herein in which a first rule set for routing packets received by a group of switches during a first time period is to be updated to a second rule set. During a transition period, at least some switches in the group of switches route packets to a controller, while other switches in the group of switches route packets to a next hop that is unchanged by the change in the rule set. The controller forwards packets that are received from at least some of the switches in the group to a destination node each of the packets, as determined from the updated rule set.

Abstract: Continuous recording multichannel disk-based data logging apparatus. The apparatus includes a plurality of disk drives and an interface including a plurality of parallel inputs. The interface is responsive to data at the inputs to write the data on an active plurality of the disk drives, at least one disk drive being idle. The interface is responsive to a user request for data on one of the active disk drives to substitute an idle disk drive into the active plurality in place of that one, to read the requested data, and to cause that one to become idle.