Distributed cache for state transfer operations

• US 8,032,642 B2
• Filed: 01/26/2010
• Issued: 10/04/2011
• Est. Priority Date: 02/13/2001
• Status: Expired due to Fees

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Aventail LLC
• Inventors: Erickson, Rodger D.
• Primary Examiner(s): Lim; Krisna
• Application Number:
  US12/694,198
• Publication Number:
  US 20100185728A1
• Time in Patent Office: 616 Days
• Field of Search: 709223-227, 714/4, 714/1, 714/2, 714/4.11, 726/4, 726/5, 726/12, 726/14, 726/18
• US Class Current: 709/227
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/10015 Access to distributed or replicated servers, e.g. using brokers
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/148 Migration or transfer of sessions
• CPC Class Codes: H04L 67/288 Distributed intermediate devices, i.e. intermediate devices for interaction with other intermediate devices on the same level
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A network arrangement that employs a cache having copies distributed among a plurality of different locations. The cache stores state information for a session with any of the server devices so that it is accessible to at least one other server device. Using this arrangement, when a client device switches from a connection with a first server device to a connection with a second server device, the second server device can retrieve state information from the cache corresponding to the session between the client device and the first server device. The second server device can then use the retrieved state information to accept a session with the client device.

Claims

1. A system for maintaining session based communications with a client computer, the system comprising:

a first server for communicating with the client computer, the first server employing a cache memory storing at least a portion of state information for a session with the client computer; and

a second server employing a cache memory storing necessary portions of state information for the session with the client computer, wherein the client computer may switch connection to the second server when connection with the first server terminates while maintaining the state information established between the client computer and the first server, and wherein the second server may request additional portions of state information from the first server if the additional portions of the state information are not immediately present at the second server upon establishment of the connection with the client computer.

2. The system of claim 1, further comprising a third server employing a cache memory storing the additional portions of state information not immediately present at the second server upon establishment of the connection with the second server, wherein the second server may request the additional portions of state information from the third server when a connection cannot be established between the first server and the second server for the requested additional portions of state information.

3. A system for maintaining state information, the system comprising:

a plurality of server computers, each server computer employing state information reflecting a communication session with an associated client computer, wherein the client computer may switch a connection from a first server of the plurality of server computers to a second server of the plurality of the server computers while maintaining the state information established between the client computer and the first server;

a cache repository for storing a cache containing the state information for each of the plurality of server computers; and

a plurality of cache memories, each cache memory being associated with one of the plurality of server computers and storing only a portion of the cache stored in the cache repository.

4. The system of claim 3, wherein the state information is credential information.

5. The system of claim 4, wherein the credential information includes Secure Sockets Layer (SSL) session identifiers.

6. The system of claim 4, wherein the credential information includes authentication information.

7. The system of claim 3, wherein the state information includes Transmission Control Protocol/Internet Protocol (TCP/IP) header information.