Abstract: A data communications device includes a supervisory circuit, a power supply, and a power circuit. The power circuit includes a data communications port, a power supply connection coupled to the power supply, and a power controller coupled to the data communications port and the power supply connection. The power controller is configured to provide a power signal from the power supply connection to the data communications port in response to communication with the supervisory circuit. Upon loss of communication with the supervisory circuit, the power controller is configured to selectively continue to provide the power signal from the power supply connection to the data communications port when a local parameter has a first value, and discontinue providing the power signal from the power supply connection to the data communications port when the local parameter has a second value.

Abstract: A method of protecting a data network from denial of service (DOS) attacks is described. The method may use various network tools to selectively block or disable portions of a data trunk experiencing a DOS attack, thereby preventing the DOS attack from reaching at least some resources on the network. In one embodiment, a network switch identifies a virtual LAN (VLAN) carrying suspect data on a data trunk. The network switch then adjusts a spanning tree for the network so that one or more ports on the compromised VLAN are blocked or disabled, while non-compromised VLANs are allowed to continue carrying data. Other approaches are also presented for avoiding the loss of valid data when a network blocks one or more VLANs or other portions of a network in response to a DOS attack or other intrusion.

Abstract: A solution is provided wherein physical link parameters may be negotiated after a link is brought up by having the two devices involved in the link exchange identifiers when the link is initially brought up. These identifiers may be saved in the devices and then utilized upon receipt of subsequent physical link parameter negotiation packets to ensure that these packets are received by a partner who is connected via a physical link.

Abstract: The present invention provides a power negotiation protocol that enables PDs and PSEs to negotiate the amount of inline power that a PD consumes and the corresponding PSE provides. This power negotiation allows the PDs provide fine-grained power consumption level to PSEs, and the PSEs are able to manage inline power efficiently using the negotiation protocol of the present invention. The PDs can ask the PSEs for more power when needed rather than having to constantly reserve the maximum amount of power they can consume at all times. Similarly, the PDs can release reservation of excess power when their respective power requirements decrease. The PSEs can limit the amount of power that can be consumed by the PD, thereby providing the ability for an administrator to control how much power a given PD can consume.

Abstract: A data communications device includes a supervisory circuit, a power supply, and a power circuit. The power circuit includes a data communications port, a power supply connection coupled to the power supply, and a power controller coupled to the data communications port and the power supply connection. The power controller is configured to provide a power signal from the power supply connection to the data communications port in response to communication with the supervisory circuit. Upon loss of communication with the supervisory circuit, the power controller is configured to selectively continue to provide the power signal from the power supply connection to the data communications port when a local parameter has a first value, and discontinue providing the power signal from the power supply connection to the data communications port when the local parameter has a second value.

Abstract: A data communications device includes a supervisory circuit, a power supply, and a power circuit. The power circuit includes a data communications port, a power supply connection coupled to the power supply, and a power controller coupled to the data communications port and the power supply connection. The power controller is configured to provide a power signal from the power supply connection to the data communications port in response to communication with the supervisory circuit. Upon loss of communication with the supervisory circuit, the power controller is configured to selectively continue to provide the power signal from the power supply connection to the data communications port when a local parameter has a first value, and discontinue providing the power signal from the power supply connection to the data communications port when the local parameter has a second value.