Aligning data packets/frames for transmission over a network channel

• US 20030031202A1
• Filed: 05/15/2001
• Published: 02/13/2003
• Est. Priority Date: 05/15/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: WebEx Communications Incorporated (Cisco Systems, Inc.)
• Inventors: Teng, Chia-Yuan
• Granted Patent: US 7,031,342 B2
• Time in Patent Office: Days
• US Class Current: 370/469
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/166 IP fragmentation; TCP segmentation
• CPC Class Codes: H04L 69/168 specially adapted for link layer protocols, e.g. asynchronous transfer mode [ATM], synchronous optical network [SONET] or point-to-point protocol [PPP]
• CPC Class Codes: H04L 69/32 Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

Data transmission over a network is disclosed. The data transmission includes aligning boundaries of application, transport, network, and data link layer packets. The transmission also includes receiving data transmission channel information, and determining a suitable number of data link layer packets per application/transport/network layer packet. The determination is based on the channel information. The suitable number of data link layer packets allows continuous alignment between the boundaries of the application, transport

Claims

1. A method for transmitting data over a network, comprising:

aligning boundaries of application, transport, network, and data link layer packets;

receiving data transmission channel information; and

determining a suitable number of data link layer packets per application/transport/network layer packet based on said channel information, said suitable number of data link layer packets allowing continuous alignment between the boundaries of the application, transport, network, and data link layer packets.

2. The method of claim 1, wherein the continuous alignment, between boundaries of the application, transport, network, and data link layer packets, is maintained by controlling a size of the application/transport/network layer packet as a multiple of data link layer packet size.

3. The method of claim 1, wherein the application layer packet includes an independent decoding unit (IDU).

4. The method of claim 3, wherein the transport/network layer packet includes a datagram.

5. The method of claim 4, wherein the data link layer packet includes a frame.

6. The method of claim 5, wherein said data transmission channel information includes a frame error rate (P_e,f), a frame size (F), an IDU/datagram header size (H), and a maximum number of retransmissions allowed (L).

7. The method of claim 6, wherein said determining the suitable number of data link layer packets includes computing the suitable number of frames per IDU/datagram as

8. The method of claim 7, wherein the frame error rate (P_e,f) is determined to be sufficiently small when the frame error rate (P_e,f) is less than 0.2%.

9. The method of claim 6, wherein said data transmission channel information also includes an IDU error rate (P_e,d)

10. The method of claim 9, wherein said determining the suitable number of data link layer packets includes computing the suitable number of frames per IDU/datagram by finding a solution to

11. The method of claim 10, wherein the frame error rate (P_e,f) is determined not to be sufficiently small when the frame error rate (P_e,f) is greater than or equal to 0.2%.

12. The method of claim 10, wherein the IDU error rate (P_e,d) after L retransmissions is determined to be sufficiently small when the IDU error rate (P_e,d) is less than 5%.

13. The method of claim 9, wherein said determining the suitable number of data link layer packets includes computing the suitable number of frames per IDU/datagram by finding a solution to

14. The method of claim 13, wherein the IDU error rate (P_e,d) after L retransmissions is determined not to be sufficiently small when the IDU error rate (P_e,d) after L retransmissions is greater than or equal to 5%.

15. A method for determining a suitable number of frames per IDU/datagram, comprising:

receiving data transmission channel information including a frame error rate (P_e,f), an IDU error rate (P_e,d), a frame size (F), a datagram header size (H), and a maximum number of retransmissions allowed (L); and

computing the suitable number as

$\sqrt{\frac{H}{{\mathrm{FP}}_{e,f}}},$

when the frame error rate (P_e,f) is sufficiently small,

finding a solution to

$H-\underset{i=2}{\overset{L}{\sum <br><br>}}<br><br>P_{e,f}^{i-1}<br><br>\left({\mathrm{HP}}_{e,f}+F\right)<br><br>\left(i-1\right)<br><br>k^i-{\mathrm{LFP}}_{e,f}^L<br><br>k^{L+1}=0,$

when the frame error rate (P_e,f) is not sufficiently small, but the IDU error rate (P_e,d) after L retransmissions is sufficiently small, or

finding a solution to

$H-\underset{i=2}{\overset{L}{\sum <br><br>}}<br><br>P_{e,f}^{i-1}<br><br>\left({\mathrm{HP}}_{e,f}+F\right)<br><br>\left(i-1\right)<br><br>k^i-\left(\mathrm{LF}+\left(L+2\right)<br><br>{\mathrm{HP}}_{e,f}\right)<br><br>P_{e,f}^L<br><br>k^{L+1}-{\mathrm{FP}}_{e,f}^{2<br><br>L+1}<br><br>k^{2<br><br>L+2}+\underset{i=0}{\overset{L-1}{\sum <br><br>}}<br><br>\left(i-L-1\right)<br><br>\left({\mathrm{HP}}_{e,f}+F\right)<br><br>P_{e,f}^{i+L+1}<br><br>k^{i+L+2}=0,$

when the frame error rate (P_e,f) is not sufficiently small, and the IDU error rate (P_e,d) after L retransmissions is also not sufficiently small.

16. A data transmission system, comprising:

a calculator arranged to receive data transmission channel information, and to determine a suitable number of frames per datagram; and

a packet builder arranged to receive data in a form of datagram, said packet builder to align and segment the datagram into said suitable number of frames.

17. The system of claim 16, wherein said packet builder aligns and segments the datagram into said suitable number of frames so that an alignment of datagram and frame boundaries is maintained by controlling a size of the datagram as a multiple of frame size.

18. The system of claim 16, further comprising:

a channel interface module to receive and output frames, whose numbers are appropriately sized with respect to the datagram.

19. The system of claim 16, wherein said calculator includes:

at least one comparator to compare frame error rate, before and after retransmissions, with first and second threshold values, respectively, said at least one comparator outputting a decision signal based on comparisons made with said first and second threshold values; and

a processor to receive data transmission channel information, said processor computing the suitable number of frames per datagram based on the data transmission channel information and said decision signal.

20. The method of claim 19, wherein said data transmission channel information includes a frame error rate (P_e,f), an IDU error rate (P_e,d), a frame size (F, an IDU/datagram header size (H), and a maximum number of retransmissions allowed (L).

21. The system of claim 20, wherein said decision signal commands the processor to compute the suitable number of frames per datagram as

22. The system of claim 20, wherein said decision signal commands the processor to compute the suitable number of frames per datagram by finding a solution to

H−

P_e,f<sup>i−

1</sup>(HP_e,f+F)(i−

1)kⁱ−

LFP_e,f^Lk^L+1=0

when the frame error rate is greater than or equal to the first threshold value, but the IDU error rate after L retransmissions is less than the second threshold value.

23. The system of claim 20, wherein said decision signal commands the processor to compute the suitable number of frames per datagram by finding a solution to