Abstract: A system and method for dispensing and simultaneously metering bulk material from storage bins, silos, rail cars, and other bulk material storage structures is provided. The bulk material metering system is configured to stop the flow of the bulk material on demand. The system is robust and capable of reliably and accurately dispensing and metering bulk materials with minimal maintenance.

Abstract: A system and method for dispensing and simultaneously metering bulk material from storage bins, silos, rail cars, and other bulk material storage structures is provided. The bulk material metering system is configured to stop the flow of the bulk material on demand. The system is robust and capable of reliably and accurately dispensing and metering bulk materials with minimal maintenance.

Abstract: Method and devices are provided for allocating network resources in a flexible manner. In some implementations, a customer's unused resources for a particular type of service are assigned to another type of service. In other implementations, a first customer's unused resources are assigned to a second customer, e.g., in exchange for a relatively lower service charge to the first customer. The unused bandwidth may be assigned on a hierarchical or a non-hierarchical basis. In preferred embodiments, resources are allocated using a token bucket methodology. Preferably, high-priority resources are not compromised by the allocation scheme. The discipline or manner in which resources or bandwidth are shared may be specified in a static fashion or information regarding the state of congestion in the network maybe used to generate a dynamic (time varying) specification.

Abstract: Various systems and methods for preventing loops in the presence of control plane failures are disclosed. For example, one method involves sending a special data packet in response to detection of a break in a network loop and then unblocking a port if the special data packet fails to circumnavigate the network loop. Prior to detection of the break, the port was blocked by a loop prevention protocol, such as a spanning tree protocol. If the special data packet successfully circumnavigates the network loop, the port will not be unblocked.

Abstract: Various systems and methods for implementing virtual ports within ring networks are disclosed. For example, one method involves allocating a logical port that corresponds to a first port and a second port and instantiating a spanning tree protocol instance. The first port and the second port are both assigned to a first ring network. The spanning tree protocol instance selectively blocks the logical port; however, the spanning tree protocol instance is unable to block the first port independently of blocking the second port. Events (e.g., link failures and recoveries) that occur within the ring network are communicated to spanning tree by transitioning the state of the logical port in response to receiving a ring protocol control packet. The spanning tree protocol instance initiates a bridge protocol data unit (BPDU) exchange from the logical port in response to a transition in the state of the logical port.

Abstract: Various systems and methods for implementing virtual ports within ring networks are disclosed. For example, one method involves allocating a logical port that corresponds to a first port and a second port and instantiating a spanning tree protocol instance. The first port and the second port are both assigned to a first ring network. The spanning tree protocol instance selectively blocks the logical port; however, the spanning tree protocol instance is unable to block the first port independently of blocking the second port. Events (e.g., link failures and recoveries) that occur within the ring network are communicated to spanning tree by transitioning the state of the logical port in response to receiving a ring protocol control packet. The spanning tree protocol instance initiates a bridge protocol data unit (BPDU) exchange from the logical port in response to a transition in the state of the logical port.

Abstract: In some ring protocols, control messages are exchanged among ring nodes in order to implement certain behaviors, such as loop-free behavior and/or failure recovery, within the ring. A segment of a ring can be replaced by another network, effectively turning the ring into a daisy chain. If the intervening network does not allow transmission of the control messages used by the ring protocol, certain control messages may be blocked, causing the ring to operate in undesirable ways. Reflector ports can be implemented at each end of the daisy chain in order to prevent these control messages from being blocked.

Abstract: Method and devices are provided for allocating network resources in a flexible manner. In some implementations, a customer's unused resources for a particular type of service are assigned to another type of service. In other implementations, a first customer's unused resources are assigned to a second customer, e.g., in exchange for a relatively lower service charge to the first customer. The unused bandwidth may be assigned on a hierarchical or a non-hierarchical basis. In preferred embodiments, resources are allocated using a token bucket methodology. Preferably, high-priority resources are not compromised by the allocation scheme. The discipline or manner in which resources or bandwidth are shared may be specified in a static fashion or information regarding the state of congestion in the network maybe used to generate a dynamic (time varying) specification.