Method and apparatus for bridging between networks

A network, comprising a plurality of network segments, wherein said network segments are connected together by one or more network connection components, and one or more of the network connection components is a network layer bridge, wherein said network layer bridge comprises:

• a plurality of ports, each for connection to a different network segment, wherein a first port is for connection to a first network segment and a second port is for connection to a second network segment;
• a memory for storing network layer addresses for nodes together with corresponding port identifiers and data link layer addresses, wherein the memory is adapted to store data link layer addresses of more than one type;
• wherein the network layer bridge is adapted to discover corresponding port identifier and data link layer address for a network layer address for which these are not already known;
• and to forward a message from a first node connected through the first network segment to the first port to a second node connected through the second network segment to the second port when the corresponding port identifier and data link level address for both the first and second node are stored in the memory, wherein the message is addressed with the network layer address of the second node, and the network layer bridge directs the message through the corresponding port to the corresponding data link level address for the second node;
• and
• wherein there are a plurality of said network level bridges in the network, and the network level bridges are adapted to communicate to run a spanning tree algorithm to prevent loops arising in a portion of the network.

A method of bridging between first and second network segments with different data link layer addressing, comprising:

• connecting the first network segment to a first port of a network layer bridge and the second network segment to a second port of the network layer bridge, the network layer bridge comprising a memory for retaining values for nodes of network layer address with a corresponding data link layer address and port identifier, wherein the memory is adapted to store data link level addresses of more than one type;
• a first node connected to the network layer bridge through the first network segment sending an address resolution message to elicit the corresponding data link layer address for a second node connected to the network layer bridge through the second network segment;
• storing in the memory the network layer address with the corresponding data link layer address and port identifier of the first node;
• sending if necessary through the second port an address resolution message to elicit the corresponding data link layer address and port identifier for the second node;
• once the network layer address, data link layer address and port identifier of the first node and second node are stored in the memory, transmitting messages between the first and second node by sending of a message from one said node with the network layer address of the other said node, and direction of the message by the network layer bridge to the other said node through the appropriate port to the appropriate data link layer address for the other said node,
• wherein either the first or second network segment has a data link layer with dynamic addressing;
• and wherein said data link layer with dynamic addressing is in accordance with IEEE 1394-1995;
• and wherein the memory is adapted to store data link layer addresses for said data link layer with dynamic addressing which includes UID.