Generic label encapsulation protocol for carrying label switched packets over serial links

• US 6,331,978 B1
• Filed: 03/09/1999
• Issued: 12/18/2001
• Est. Priority Date: 03/09/1999
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Vaananen, Pasi, Strandberg, Ove, Ravikanth, Rayadurgam
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US09/264,758
• Time in Patent Office: 1,015 Days
• Field of Search: 370/392, 370/401, 370/449, 370/467, 370/474, 370/216, 370/229, 370/230, 370/231, 370/242, 370/244, 370/389, 370/412, 370/413, 370/414, 370/465, 370/471, 714/746, 714/752, 714/758, 714/759, 714/774, 714/776, 714/781, 714/785, 714/819
• US Class Current: 370/392
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13174 Data transmission, file transfer
• CPC Class Codes: H04Q 2213/13204 Protocols
• CPC Class Codes: H04Q 2213/13215 Code checking, CRC
• CPC Class Codes: H04Q 2213/13216 Code signals, frame structure
• CPC Class Codes: H04Q 2213/1329 Asynchronous transfer mode, ATM
• CPC Class Codes: H04Q 2213/13348 Channel/line reservation
• CPC Class Codes: H04Q 2213/13367 Hierarchical multiplexing, add-drop multiplexing
• CPC Class Codes: H04Q 2213/13389 LAN, internet

Abstract

A method for encapsulation of labeled datagrams over serial communications links, and a method for extracting the datagrams on the receiving end of the link. The encapsulation method includes adding a label and a label error correction to the front of a datagram, the label error correction being derived using the label and adding a cyclic redundancy check at a trailing end of the datagram, the cyclic redundancy check being derived using the datagram. The end of a packet encapsulating the datagram with a label, a label error correction field and a cyclic redundancy check field is identified by analyzing incoming bits for a packet until a pattern of bits is detected that matches a number of previous bits of the packet coded with a predetermined coding formula and identifying the end of the packet based upon the detection of the match and the predetermined coding formula. The end of the current frame may be identified by coding incoming bits according to the cyclic redundancy check polynomial to produce a calculated cyclic redundancy check until the calculated cyclic redundancy check matches the cyclic redundancy check field. In addition, or alternatively, the end of the previous frame may be identified by coding incoming bits according to the label error correction polynomial to produce a calculated label error correction until the label error correction matches the label error correction field.

Claims

1. A method for encapsulating a label in a packet enabling label switching of the packet over serial links, comprising:

adding a multi-protocol label and a multi-protocol label error correction to the front of a datagram, the label error correction being delivered using the label and the multi-protocol label error correction enabling identification of the end of the packet; and

adding a cyclic redundancy check at a trailing end of the datagram, the cyclic redundancy check being derived using the datagram.

2. The method of claim 1 wherein the label includes three bytes.

4. The method of claim 1 wherein the datagram is scrambled.

5. The method of claim 4 wherein the datagram is scrambled according to D⁴³+1.

6. The method of claim 1 wherein the cyclic redundancy check is obtained using a polynomial D¹⁶+D¹⁵+D²+1.

7. The method of claim 1 wherein the datagram is an IPv4 packet.

8. The method of claim 1 wherein the datagram is an IPv6 packet.

9. The method of claim 1 wherein the label comprises a plurality of bits, wherein a bit in the label is a label significant bit for indicating that no payload is being carried.

10. The method of claim 1, wherein the multi-protocol label includes address information and non-address information.

3. The method of 1 wherein the label error correction is obtained according to D⁸+D²+D+1.

11. A method for identifying an end of a packet encapsulating the datagram with a label, a label error correction field and a cyclic redundancy check field, comprising:

analyzing incoming bits of the encapsulating packet until a pattern of bits is detected that matches a number of previous bits of the packet encoded with a predetermined coding formula that includes a label error correction polynomial, wherein analyzing includes coding incoming bits according to the label error correction polynomial to produce a calculated label error correction until the label error correction matches the label error correction field; and

identifying the end of the packet based upon the detection of the match and the predetermined coding formula.

12. The method of claim 11 wherein the predetermined coding formula further comprises a cyclic redundancy check polynomial and the analyzing further comprises coding incoming bits according to the cyclic redundancy check polynomial to produce a calculated cyclic redundancy check until the calculated cyclic redundancy check matches the cyclic redundancy check field.

13. The method of claim 12 wherein the identifying further comprises identifying the end of the current packet based upon the detection of the match.

14. The method of claim 11 wherein the identifying further comprises identifying the end of the previous packet based upon the detection of the match.

15. The method of claim 11, further comprising extracting the payload from the packet after identifying the end of the packet.

16. A packet network, comprising:

an ingress entity for receiving a datagram and encapsulating the datagram with a multi-protocol label for controlling the processing of the datagram, a multi-protocol label error correction field and a cyclic redundancy check field to produce a labeled packet, and forwarding the packet to a next hop; and

an egress entity for identifying an end of the packet encapsulating the datagram with the label, the label error correction field and the cyclic redundancy check field and for identifying the end of the packet by analyzing incoming bits for the packet until a pattern of bits is detected that matches a number of previous bits of the packet coded with a label error correction formula.

17. The packet network of claim 16 wherein the ingress entity encapsulates the datagram by adding a label and a label error correction derived using the label to the front of a datagram and adding a cyclic redundancy check derived using the datagram at a trailing end of the datagram.

18. The packet network of claim 17 wherein the label includes three bytes.

19. The packet network of claim 17 wherein the label error correction is obtained according to D⁸+D²+D+1.

20. The packet network of claim 17 wherein the datagram is scrambled.

21. The packet network of claim 20 wherein the datagram is scrambled according to D⁴³+1.

22. The packet network of claim 17 wherein the cyclic redundancy check is obtained using a polynomial D¹⁶+D¹⁵+D²+1.

23. The packet network of claim 17 wherein the datagram is an IPv4 packet.

24. The packet network of claim 17 wherein the datagram is an IPv6 packet.

25. The packet network of claim 17 wherein the label comprises a plurality of bits, wherein a bit in the label is a label significant bit for indicating that no payload is being carried.

26. The packet network of claim 16 wherein the egress entity further codes incoming bits according to a cyclic redundancy check polynomial to produce a calculated cyclic redundancy check until the calculated cyclic redundancy check matches the cyclic redundancy check field.

27. The packet network of claim 26 wherein the selecting further comprises the identifying the end of the current packet based upon the detection of the match.

28. The packet network of claim 16 wherein the label error correction formula comprises a label error correction polynomial, the egress entity coding incoming bits according to the label error correction polynomial to produce a calculated label error correction until the label error correction matches the label error correction field.

29. The packet network of claim 28 wherein the selecting further comprises the identifying the end of the previous packet based upon the detection of the match.

30. The packet network of claim 16 wherein the label error correction formula comprises a combination of a cyclic redundancy check polynomial and a label error correction polynomial, the egress entity coding incoming bits according to the cyclic redundancy check polynomial and the label error correction polynomial, wherein the egress entity uses the cyclic redundancy check polynomial to produce a calculated cyclic redundancy check until the calculated cyclic redundancy check matches the cyclic redundancy check field and the label error correction polynomial to produce a calculated label error correction until the label error correction matches the label error correction field.

31. The packet network of claim 16, wherein the egress entity further extracts the datagram from the packet after identifying the end of the packet.

32. The packet network of claim 16, wherein the packet encapsulating the datagram is of a length unknown to the egress entity until the egress entity has identified the end of the packet.

33. The packet network of claim 16, wherein the multi-protocol label includes address information and non-address information.