Encoding virtual LAN tags
View Patent ↗Various embodiments are disclosed for encoding and decoding VLAN identifiers. One such method includes mapping the VLAN identifier, associated with the frame, to a number of extra bytes. The method also includes appending, to the payload, a quantity of bytes equal to the number of extra bytes. The method also includes setting at least one of the appended bytes to a value of a length provided with the frame. The method also includes transmitting the frame, including the appended bytes.
1. A method of encoding a virtual local area network (VLAN) identifier into a frame comprising a header and a payload, the method comprising:
mapping the VLAN identifier, associated with the frame, to a number of extra bytes;
appending, to the payload, a quantity of bytes equal to the number of extra bytes;
setting at least one of the appended bytes to a value of a length parameter provided with the frame; and
transmitting the frame, including the appended bytes.
2. The method of claim 1 , wherein the setting comprises:
setting contents of m bytes at an end of the appended bytes to the value of the length parameter; wherein m is an integer.
3. The method of claim 1 , wherein the mapping comprises:
computing the number of extra bytes as a product of m and the sum of 1 and the VLAN identifier, wherein m represents a minimum number of bytes required to carry a maximum size frame, and m is an integer.
4. The method of claim 1 , wherein the mapping comprises:
computing the number of extra bytes as the sum of 2 and twice the VLAN identifier.
5. The method of claim 1 , wherein the mapping comprises:
performing a left shift operation on the VLAN identifier; and
adding 2 to the left-shifted VLAN identifier to produce the number of extra bytes.
6. The method of claim 1 , further comprising:
obtaining the frame from a network layer driver.
7. The method of claim 1 , further comprising:
obtaining the frame from a service/application functional entity (SAFE).
8. The method of claim 1 , further comprising:
obtaining the frame from a Media Access Control (MAC) layer driver.
9. The method of claim 1 , wherein the transmitting comprises:
delivering the frame to a Network Interface Controller (NIC).
10. The method of claim 1 , wherein the transmitting comprises:
delivering the frame to a physical layer transceiver (PHY).
11. The method of claim 1 , wherein the transmitting comprises:
delivering the frame to a physical layer transceiver (PHY) via a Management Independent Interface (MII).
12. A method of decoding a virtual local area network (VLAN) identifier from a frame comprising a header and a payload, the method comprising:
receiving the frame, having a length, on a local area network (LAN);
obtaining an untagged length value from m bytes at an end of the frame, wherein m is an integer;
calculating a difference between the length of the received frame and the untagged length value;
mapping the difference to obtain the VLAN identifier; and
providing the VLAN identifier to a consumer of the frame.
13. The method of claim 12 , wherein the length of the received frame is determined from a frame delimiter recognized by a physical layer.
14. The method of claim 12 , wherein the length of the received frame is determined from an interframe gap (IFG) recognized by a physical layer.
15. The method of claim 12 , wherein the mapping comprises:
computing the VLAN identifier as one less than the difference divided by m, wherein m represents a minimum number of bytes required to carry a maximum size frame.
16. The method of claim 12 , wherein the mapping comprises: subtracting 2 from the difference to obtain an intermediate value; and performing a right shift operation on the intermediate value to produce the VLAN identifier.
17. The method of claim 12 , wherein the consumer is a network layer of a protocol stack.
18. The method of claim 12 , wherein the consumer is a Media Access Control (MAC) layer of a protocol stack.
19. A device for handling a frame comprising a header and a payload, the device comprising:
a physical layer device (PHY); and
processing circuitry configured to:
map a VLAN identifier, associated with the frame, to a number of extra bytes;
append, to the payload, a quantity of bytes equal to the number of extra bytes;
set at least one of the appended bytes to a length parameter provided with the frame; and
provide the frame, including the appended bytes, to the PHY for transmission.
20. The device of claim 19 , the processing circuitry further configured to compute the number of tag bytes as a product of m and the sum of 1 and the VLAN identifier, wherein m represents a minimum number of bytes required to carry a maximum size frame, and m is an integer.