Modified ethernet preamble for inter line card communications in a modular communication chassis
A method of providing information regarding an Ethernet frame, within the Ethernet preamble of the Ethernet frame, comprises inserting into the Ethernet preamble an inter-line-card header that includes a start control character, a version number, a parity bit, a source port, a destination port, and a forwarding domain entry; and preserving said inter-line-card header, inside of said Ethernet preamble, in a Media Access Control (MAC) sub-layer in said Ethernet frame. The method may include a step of selecting the decoding format for the inter-line-card header corresponding to the version number and/or forwarding other Ethernet frames according to additional forwarding information provided by the forwarding domain entry. The inter-line-card header may be preserved in the MAC sub-layer by keeping the Ethernet preamble at the beginning of an Ethernet frame received over an Ethernet backplane, and passing the combined preamble and associated Ethernet frame to an inter-line-card header processing module.
1. A method of providing information regarding an Ethernet frame for transmission within a communication chassis with a plurality of line cards interconnected via an Ethernet backplane and via point to point links, said method comprising:
modifying, at one of said plurality of line cards, an Ethernet preamble of the Ethernet frame to include the information regarding the Ethernet frame, creating a modified Ethernet preamble;
preserving by a Media Access Control (MAC) sub-layer module said modified Ethernet preamble; and
transmitting said modified Ethernet frame to another one of said plurality of line cards located within said communication chassis.
2. The method of claim 1 wherein the information regarding the Ethernet frame comprises at least one of a start control character, a version number, a parity bit, a source port, a destination port, a forwarding domain entry, an action field, and an action parameter.
3. A method of efficiently transmitting an Ethernet frame between a plurality of line cards of a communication chassis, said method comprising:
modifying an Ethernet preamble of said Ethernet frame to include information associated with the Ethernet frame, creating a modified Ethernet preambleJoe Bassett <[email protected]>
preserving by a Media Access Control (MAC) sub-layer module said modified Ethernet preamble; and
transmitting said modified Ethernet frame to another one of said plurality of line cards located within said communication chassis.
4. The method of claim 3 wherein the information associated with the Ethernet frame comprises at least one of a start control character, a version number, a parity bit, a source port, a destination port, a forwarding domain entry, an action field, and an action parameter.