Abstract: Techniques are disclosed that may allow a network device comprising multiple line cards that are each executing a spanning tree algorithm to appear as a single spanning tree protocol entity to other network devices within a bridged local area network (LAN). In one example, a method includes determining, via a first processor on a first card of a network device, a first superior local port on the first card, transmitting, from the first card to a second card of the network device, a data unit specifying the determined first superior local port, and determining, via a second processor on the second card, a superior port on the network device among the first superior local port and a second plurality of ports on the second card based on a second plurality of BPDUs received via the second plurality of ports.

Abstract: In general, this disclosure describes techniques that may allow multiple spanning tree networks to be joined across a ring network. In a ring topology, e.g., an Ethernet ring topology, there are multiple nodes connected one to another to form a ring. Subtending from the ring network are customer devices that may joined together to form networks, e.g., Ethernet networks. Providing only a single connection between a subtending network and the ring network risks isolating the subtending network from the ring network if a fault occurs on the connecting link. Providing two links between a subtending network and the ring network, however, may create an undesirable traffic loop. One example protocol used by the customer devices to communicate with one another in a network and prevent looping paths is Spanning Tree Protocol.

Abstract: Techniques are disclosed that may allow a network device comprising multiple line cards that are each executing a spanning tree algorithm to appear as a single spanning tree protocol entity to other network devices within a bridged local area network (LAN). In one example, a method includes determining, via a first processor on a first card of a network device, a first superior local port on the first card, transmitting, from the first card to a second card of the network device, a data unit specifying the determined first superior local port, and determining, via a second processor on the second card, a superior port on the network device among the first superior local port and a second plurality of ports on the second card based on a second plurality of BPDUs received via the second plurality of ports.

Abstract: A portable anchor for tethering to on the shelf of a rock quarry includes an elongated lower post adapted into slip charge holes drilled in the quarry shelf, a stop plate connected to the post and rotatably resting on the shelf, and hook receiving means for connection of one end of a tether line that is connected at the other end to a harness or belt worn by the worker. A method for anchoring to said quarry shelf includes providing an anchor adapted to slip into the charge receiving holes formed in the shelf, and having a stop plate for positioning the depth of the anchor in the charge hole.