Level two first-in-first-out transmission
A hardware state machine connected to a processor, the hardware state machine configured to receive operational codes from the processor; a multiplexer connected to the processor, the hardware state machine and a checksum circuit, the multiplexer configured to receive data from the processor; and a transmit circuit connected to the multiplexer, the transmit circuit configured to receive data from the multiplexer for transmission to a far end device, wherein the hardware state machine is further configured to, responsive receiving one or more operational codes from the processor: cause the checksum circuit to alter a checksum value of a first data packet being transmitted by the transmit circuit; and cause the transmit circuit to preempt transmission of the first data packet and begin transmitting a second data packet once the checksum value so altered has been transmitted from the transmit circuit.
1. A circuit comprising:
a first transmitter circuit configured to:
receive a first set of data;
thereafter, receive a second set of data having a priority;
based on the priority of the second set of data, generate a first Ethernet packet for the first set of data that includes a first packet fragment and a second packet fragment;
generate a second Ethernet packet for the second set of data; and
provide the first packet fragment, the second packet fragment, and the second Ethernet packet; and
a second transmitter circuit coupled to the first transmitter circuit and configured to:
receive the first packet fragment, the second packet fragment, and the second Ethernet packet; and
transmit the second Ethernet packet between the first packet fragment and the second packet fragment.
2. The circuit of claim 1 , wherein the first packet fragment includes a value that indicates that the first packet fragment is a fragment.
3. The circuit of claim 2 , wherein the value in the first packet fragment indicates a count of fragments that make up in the first Ethernet packet.
4. The circuit of claim 2 , wherein the value in the first packet fragment indicates a sequence number of the first packet fragment.
5. The circuit of claim 1 , wherein the first packet fragment includes a cyclical redundancy check value that indicates that the first packet fragment is a fragment.
6. The circuit of claim 5 , wherein the first transmitter circuit is configured to:
generate a cyclical redundancy check value for the first Ethernet packet; and
thereafter generate the cyclical redundancy check value for the first packet fragment.
7. The circuit of claim 1 , further comprising:
a receiver circuit configured to receive a third Ethernet packet; and
a multiplexer that includes a first input coupled to the receiver circuit; a second input coupled to the first transmitter circuit; and an output coupled to the second transmitter circuit.
8. The circuit of claim 7 , wherein the second transmitter circuit is configured to forward the third Ethernet packet.
9. The circuit of claim 1 , wherein the first transmitter circuit is further configured to add a virtual local area tag to the second Ethernet packet.
10. The circuit of claim 1 , wherein the first transmitter circuit is further configured to add preamble information to the second Ethernet packet.
11. A system comprising:
a buffer;
a processor coupled to the buffer and configured to store, in the buffer, a first set of data having a first priority and a second set of data having a second priority that is greater than the first priority; and
a transmit circuit coupled to the buffer and configured to, based on the second priority being greater than the first priority:
generate a first Ethernet packet for the first set of data that includes a first packet fragment and a second packet fragment;
generate a second Ethernet packet for the second set of data; and
transmit the second Ethernet packet between the first packet fragment and the second packet fragment.
12. The system of claim 11 , wherein the first packet fragment includes a value indicating that the first packet fragment is a fragment.
13. The system of claim 12 , wherein the value in the first packet fragment indicates a count of fragments that make up in the first Ethernet packet.
14. The system of claim 12 , wherein the value in the first packet fragment indicates a sequence number of the first packet fragment.
15. The system of claim 11 , wherein the first packet fragment includes a cyclical redundancy check value that indicates that the first packet fragment is a fragment.
16. A method comprising:
receiving a first set of data for transmission over a network;
thereafter, receiving a second set of data for transmission over the network, wherein the second set of data has a priority;
based on the priority of the second set of data, generating a first Ethernet packet for the first set of data that includes a first packet fragment and a second packet fragment;
generating a second Ethernet packet for the second set of data; and
transmitting the second Ethernet packet between the first packet fragment and the second packet fragment.
17. The method of claim 16 further comprising transmitting a preamble that indicates that the second packet fragment has been preempted by the second Ethernet packet.
18. The method of claim 16 , wherein the first packet fragment includes a value that indicates that the first packet fragment is a fragment.
19. The method of claim 18 , wherein the value in the first packet fragment indicates a count of fragments that make up in the first Ethernet packet.
20. The method of claim 18 , wherein the value in the first packet fragment indicates a sequence number of the first packet fragment.