System and method for exchanging awareness information in a network environment

• US 8,098,589 B2
• Filed: 12/21/2007
• Issued: 01/17/2012
• Est. Priority Date: 07/24/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Chandra, Madhavi W., Cook, David A., Retana, Alvaro E., White, Russell I., Yang, Yi
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US11/963,003
• Publication Number:
  US 20080095169A1
• Time in Patent Office: 1,488 Days
• Field of Search: None
• US Class Current: 370/252
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/26 Route discovery packet
• CPC Class Codes: H04W 40/248 Connectivity information update

Abstract

A method for communicating packets in a network environment is provided that includes receiving a packet at a network element and identifying a sequence number included in the packet that correlates to awareness information associated with one or more adjacent network elements. A table included in the network element may be updated in order to account for the awareness information included within the packet that has not been accounted for by the network element. In cases where the awareness information included in the packet has already been accounted for, the packet may be ignored.

Claims

1. An apparatus for communicating packets in a network environment, comprising a network element configured to:

receive a packet and identify a sequence number included in the packet, wherein the sequence number is associated with a state of one or more adjacent network elements;

exchange incremental state information with the one or more adjacent network elements if the sequence number included in the packet has not already been received, the incremental state information comprising neighbor state changes that occur after receipt of a previous sequence number;

receive a full neighbor state update when a new neighbor relationship has formed between network elements; and

process the full neighbor state update if the network element is missing state information and ignore the full neighbor state update if the network element has full state information.

2. The apparatus of claim 1, wherein the network element includes a transmitter state operable to build and to communicate the packet to a selected one or more of the adjacent network elements.

3. The apparatus of claim 1, wherein when a full update of information is transmitted, it is described with a state sequence and subsequent transmissions of a protocol'"'"'s neighbor state information includes only the state sequence, and whereby if the network element receives two subsequent neighbor state packets from the same neighbor with different state sequences, the network element can request a neighbor state update from a sender by sending a currently known sequence number to a transmitting object.

4. The apparatus of claim 1, wherein the packet is a Hello packet that includes the sequence number in its corresponding header.

5. The apparatus of claim 1, wherein the packet includes a fragment value operable to indicate whether the packet is a fragment to be included with other fragments in order to comprise an entire packet that includes awareness information.

6. The apparatus of claim 1, wherein the network element includes a fragment timer operable to provide a time interval in which fragments are to be received at a selected location in a network.

7. The apparatus of claim 1, wherein the network element is operable to query a selected one of the adjacent network elements in order to receive missing awareness information, and wherein an absence of the missing awareness information is reflected by the sequence number.

8. The apparatus of claim 1, wherein the packet includes a checksum operable to provide an error detection function for the packet at receiving and transmission locations associated with a selected one or more of the network elements.

9. A method for communicating packets in a network environment, comprising:

receiving a packet at a network element;

identifying a sequence number included in the packet, wherein the sequence number is associated with a state of one or more adjacent network elements; and

exchanging incremental state information with the one or more adjacent network elements if the sequence number included in the packet has not already been received, the exchanging incremental state information comprising requesting a neighbor state update of a sender by transmitting a currently known sequence number to the sender;

receiving a full update of neighbor state information from an adjacent network element, the full update described with a state sequence; and

receiving a subsequent update of neighbor state information from the adjacent network element, the neighbor state information including only the state sequence.

10. The method of claim 9, further comprising:

building and communicating the packet to a selected one or more of the adjacent network elements.

11. The method of claim 9, wherein the packet is a Hello packet that includes the sequence number in its corresponding header.

12. The method of claim 9, wherein the packet includes a fragment value operable to indicate whether the packet is a fragment to be included with other fragments in order to comprise an entire packet that includes awareness information.

13. The method of claim 9, further comprising:

providing a time interval in which fragments are to be received at a selected location in a network, wherein the fragments comprise a Hello packet that includes awareness information.

14. The method of claim 9, further comprising:

querying a selected one of the adjacent network elements in order to receive missing awareness information, wherein an absence of the missing awareness information is reflected by the sequence number.

15. The method of claim 9, further comprising:

providing an error detection function for the packet at receiving and transmission locations associated with a selected one or more of the network elements.

16. The method of claim 9, whereby full neighbor state updates are transmitted when a new neighbor relationship has formed between network elements, and whereby neighboring network elements that already have full state information ignore the full neighbor state updates while those neighboring network elements that are missing state information process the updates.

17. The method of claim 9, wherein when a full update of information is transmitted, it is described with a state sequence and subsequent transmissions of a protocol'"'"'s neighbor state information includes only the state sequence, and whereby if the network element receives two subsequent neighbor state packets from the same neighbor with different state sequences, the network element can request a neighbor state update from a sender by sending a currently known sequence number to a transmitting object.

18. The method of claim 9, wherein, between transmissions of full adjacency state, the network element maintains local information that indicates a last neighbor state.

19. The method of claim 9, wherein changes in state are communicated with only a packet header and sequence number.

20. The method of claim 9, wherein the network element can recognize when it misses certain state information and request the state information that it missed.

21. An apparatus, comprising a first network element configured to:

receive a first packet set from a second network element, the first packet set comprising a first sequence number and a full neighbor state update of the second network element, the full neighbor state update comprising a list of neighbors of the second network element;

process the full neighbor state update;

receive a second packet set from the second network element, the second packet set comprising the first sequence number, the second packet set not comprising neighbor states; and

ignore the second packet set.

22. The apparatus of claim 21, the first network element further configured to:

receive a third packet set comprising a second sequence number; and

request incremental state information by transmitting a previously received sequence number to a sender of the third packet set;

the incremental state information comprising neighbor state changes of the sender, the neighbor state changes occurring after the sender transmitted the previously received sequence number.

23. An apparatus, comprising a first network element configured to:

receive a first packet set comprising one or more packets that each comprise a first sequence number from a second network element, the first packet set comprising a neighbor state update of the second network element, the neighbor state update comprising updated states of one or more network elements adjacent to the second network element;

receive a second packet set comprising one or more packets from the second network element, each packet of the second packet set comprising a second sequence number that is greater than the first sequence number;

request incremental state information by transmitting the first sequence number to the second network element, the incremental state information comprising neighbor state changes of the second network element, the neighbor state changes occurring after transmission of the first packet set and before transmission of the second packet set by the second network element; and

receive the requested incremental state information in a third packet set, the third packet set comprising two or more packets each comprising the second sequence number.