Reliable ISP access cloud state detection method and apparatus

• US 7,620,037 B1
• Filed: 12/14/2004
• Issued: 11/17/2009
• Est. Priority Date: 12/14/2004
• Status: Expired due to Fees

• Current Assignee: Aspen Networks, Inc.
• Original Assignee: Aspen Networks, Inc.
• Inventors: Krishnamurthy, Prashanth, Bhaskaran, Sajit, Kumar, Anmol
• Primary Examiner(s): Jagannathan; Melanie
• Application Number:
  US11/012,554
• Time in Patent Office: 1,799 Days
• Field of Search: None
• US Class Current: 370/356
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/0817 by checking functioning

Abstract

A Multi-Homing System is equipped with an Adaptive ISP Access Cloud State Detection apparatus (ACSD) that improves the reliability of the availability of digital connections (links) between computer sites, such as a Computer Premises Network and the Internet, in which such connections are made by connecting through a multiplicity of ISP Access Clouds (links). Reliability is improved over prior art methods by using data elements of Internet Protocol datagrams, e.g. record fields or bits of fields, that are regularly and normally exchanged between the ISP Access Clouds and the CPN without creating additional data traffic. Data Elements from each ISP Access Cloud are used by processing functions of the by the ACSD to test for conditions that indicate that it may be in a DOWN status. when a DOWN status is suspected, other functions in the ACSD initiate transmission of a set of PROBE packets that can reliably determine if the suspect link is actually DOWN or merely giving a response that would be interpreted as DOWN by prior art methods.

Claims

1. An adaptive MULTIHOMING SYSTEM for reliable monitoring and reporting UP/DOWN status of a plurality N of ISP-ACCESS CLOUDs connected to said adaptive MULTIHOMING SYSTEM, comprising;

a) an ACCESS CLOUD STATE DETECTION apparatus comprising;

i) a permanent memory store PM-1;

ii) a dynamic memory store DM-1;

iii) a computing resource CR-1;

comprising;

(1) a CPU-&

I/O chip set;

(2) a Control Program and a plurality of Program_Modules in cooperation with said CPU-&

I/O chip set that control the ACCESS CLOUD STATE DETECTION to execute operations, comprising;

(a) for each one of said N ISP-A/C'"'"'s, A continually and continuously read packet data flow information for packets directed to and from each one of said N ISP-A/C'"'"'s;

(b) on a first condition for a packet directed to and from each ISP-A/C-n of said N ISP-A/C'"'"'s, store said directed packet'"'"'s flow information in a TCP-Flow-Table;

(c) on a second condition for a packet directed to each ISP-ACCESS CLOUD-n of said N ISP-ACCESS CLOUDs, add TCP destination IP address of said packet to, and delete an old TCP destination IP address from, a list of TCP destination IP addresses allocated to a memory portion DYNAMIC SEED LIST in said dynamic memory;

(d) on a third condition for packets directed to an ISP-ACCESS CLOUD-n of said N ISP-ACCESS CLOUDs, update a permanent memory portion DEFAULT SEED LIST in said memory store PM-1 with said list of TCP destination IP addresses stored in Dynamic Memory-1;

(e) for each inbound packet from each ISP-ACCESS CLOUD-n of said N ISP-ACCESS CLOUDs, determine the inbound byte count, and add said count to a corresponding ISP-ACCESS CLOUD-n inbound-byte-counter, and on a regular, periodic interval of integer k-seconds, compare its inbound-byte-counter value at time=t, [ISP-n (t)] with its inbound-byte-counter value at time=t+k, [ISP-n (t+k)], and if said values are the same, set a Blackout_Hint variable to YES, and initiate an UP/DOWN status test of said ISP-ACCESS CLOUD-n to determine if said ISP-ACCESS CLOUD-n is UP or DOWN;

(f) on a fourth condition for packets directed to a TCP destination IP address, send a set PROBE of packet sequences, to said TCP destination IP address through each one of said N ISP-ACCESS CLOUDs, measure a Round Trip Time value to and from said TCP destination IP address for each one of said N ISP-ACCESS CLOUDs, and store said value for each one of said N ISP-ACCESS CLOUDs and each said destination address in a ROUND TRIP TIME table.

2. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) said first condition is the condition of every packet directed to each ISP-ACCESS CLOUD-n of said N ISP-ACCESS CLOUDs.

3. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) said second condition is the condition that said packet'"'"'s TCP destination IP address is a new TCP destination IP address not stored in said memory portion DYNAMIC SEED LIST.

4. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) said third condition is the condition that said list of TCP destination IP addresses in DM-1 are all new TCP destination IP addresses and have completely replaced a prior list of old addresses.

5. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) said fourth condition is;

said TCP destination IP address is a new TCP destination IP address.

6. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) said UP/DOWN status test is;

i) send set PROBE of packet sequences repetitively M times to through said ISP-ACCESS CLOUD-n to one or more TCP destination IP addresses;

ii) if and only if, out of said M sets of PROBE packet sequences, zero SYN ACK responses are received, then set ISP-ACCESS CLOUD-n UP/DOWN status=DOWN.

7. The adaptive MULTIHOMING SYSTEM of claim 1, wherein:

a) each PROBE set probe packet has a TCP source port number that is a number P, such that flow information <

X, Y, P, Q>

for each said probe packet is not found in said TCP-Flow-Table.

8. The adaptive MULTIHOMING SYSTEM of claim 7, wherein P is found by:

a) said ACCESS CLOUD STATE DETECTION computing resource CR-1 sets variables X, Y, Q given by X=TCP source address, Y=TCP destination IP, Q=TCP destination port=80;

b) said ACCESS CLOUD STATE DETECTION computing resource CR-1 instantiates a label GENERATE; and

calls a random number generator procedure RANDOM (P);

c) said ACCESS CLOUD STATE DETECTION computing resource CR-1 calls a Program Module SEARCH Flow Table for <

X, Y, P, Q>

in which variable flow-found=YES, if <

X, Y, P, Q>

is found in said Flow Table and then CR-1 sends control back to said label GENERATE, ELSE CR-1 sets flow-found=NO;

SET TCP source port=P.

9. The adaptive MULTIHOMING SYSTEM of claim 6, wherein:

a) said probe packet sequence PROBE is;

i) SEND SYN;

ii) RECEIVE SYN ACK;

iii) SEND FIN ACK;

iv) RECEIVE FIN ACK.

10. An adaptive MULTIHOMING SYSTEM for reliable monitoring and reporting UP/DOWN status of a plurality N of ISP-A/Cs connected to said adaptive MULTIHOMING SYSTEM, comprising:

a) an ACCESS CLOUD STATE DETECTION apparatus comprising;

i) a permanent memory store PM-1

ii) a dynamic memory store DM-1;

iii) a computing resource CR-1;

comprising;

(1) a CPU-&

I/O chip set;

(2) a Control Program and a plurality of Program_Modules in cooperation with said CPU-&

I/O chip set that control the ACCESS CLOUD STATE DETECTION apparatus, comprising;

(a) means for continually and continuously reading packet data flow information for packets directed to and from each one of said N ISP-A/C'"'"'s;

(b) means for storing said directed packet'"'"'s flow information in a TCP-Flow-Table for each and every packet of said directed packets;

(c) means for adding a TCP destination IP address of said directed packet to, and deleting an old TCP destination IP address from, a list of TCP destination IP addresses allocated to a DYNAMIC SEED LIST memory portion in said dynamic memory when said packets TCP destination IP address is a new TCP destination IP address not stored in said DYNAMIC SEED LIST memory portion and said packet is directed to one of said N ISP-A/C'"'"'s;

(d) means for updating a permanent memory portion DEFAULT SEED LIST in said memory store PM-1 with said list of TCP destination IP addresses stored in Dynamic Memory-1 when said list of TCP destination IP addresses in DM-1 are all new TCP destination IP addresses and have completely replaced a prior list of old packet addresses;

(e) means for determining the inbound byte count, and adding said count to a corresponding ISP-A/C-n inbound-byte-counter, and on a regular, periodic interval of integer k-seconds, comparing its inbound byte-counter value at time=t, [ISP-n (t)] with its inbound-byte-counter value at time=t+k, [ISP-n (t+k)], and if said values are the same, setting a Blackout_Hint variable to YES, and initiating an UP/DOWN status test of said ISP-A/C-n to determine if said ISP-A/C-n is UP or DOWN for each inbound packet from each ISP-A/C-n of said N ISP-A/C'"'"'s;

(f) means for sending said set of packet sequences, PROBE, to said destination IP address through each one of said N ISP-A/C'"'"'s, measuring a Round Trip Time value to and from said destination IP address for each one of said N ISP-A/C'"'"'s, and storing said value for each one of said N ISP-A/C'"'"'s and each said destination address in a ROUND TRIP TIME table when said destination IP address is a new TCP destination IP address for packets directed to a destination IP address.