MID-SESSION CHANGE SUPPORT IN USAGE MONITORING

1 . A method performed by a session management node for tracking usage in a subscriber network, the method comprising:

receiving, at the session management node, a usage monitoring report from a usage monitoring node, the usage monitoring report including a reported usage amount for a first monitoring key;

updating a current usage amount based upon the reported usage amount;

identifying a current monitoring key; and

requesting additional monitoring from the usage monitoring node for the current monitoring key.

2 . The method of claim 1 , wherein the current monitoring key is different from the first monitoring key.

3 . The method of claim 1 , further comprising taking a policy action based on the current usage amount.

4 . The method of claim 3 , further comprising:

determining a second usage amount associated with a second monitoring key; and

adding the current usage amount to at least the second usage amount to determine a total usage amount,

wherein the step of taking a policy action based on the current usage amount comprises taking a policy action based on the total usage amount.

5 . The method of claim 1 , wherein the step of requesting additional monitoring from the usage monitoring node for the current monitoring key comprises:

determining a next threshold based on the current usage amount; and

sending a request message to the session monitoring node including the current monitoring key and the next threshold.

6 . The method of claim 5 , further comprising:

determining a second usage amount associated with a second monitoring key; and

adding the current usage amount to at least the second usage amount to determine a total usage amount,

wherein the step of determining a next threshold based on the current usage amount comprises determining a next threshold based on the total usage amount.

7 . The method of claim 1 , further comprising:

receiving an indication that a subscription record has changed;

determining whether the current monitoring key should be changed to a new monitoring key; and

if the current monitoring key should be changed to the new monitoring key:

disabling the current monitoring key at the usage monitoring node, and

setting the current monitoring key to equal the new monitoring key.

8 . A session management node for tracking usage in a subscriber network the session management node comprising:

an interface for receiving a usage report from a usage monitoring node, the usage monitoring report including a reported usage amount for a first monitoring key;

a usage tracker configured to:

update a current usage amount based on the reported usage amount, and

identify a current monitoring key; and

a message generator configured to request additional monitoring from the usage monitoring node for the current monitoring key.

9 . The node of claim 8 wherein the current monitoring key is different from the first monitoring key.

10 . The node of claim 8 , further comprising a usage summer configured to:

determine a second usage amount associated with a second monitoring key; and

add the current usage amount to at least the second usage amount to determine a total usage amount.

11 . The node of claim 8 , further comprising a policy engine configured to take a policy action based on the current usage amount.

12 . The node of claim, further comprising a threshold calculator configured to determine a next threshold based on the current usage amount,

wherein, in requesting additional monitoring from the usage monitoring node for the current monitoring key, the message generator is configured to send a request message to the session monitoring node including the current monitoring key and the next threshold.

13 . The node of claim 8 , further comprising subscription record manager configured to receive an indication that a subscription record has changed;

wherein the usage tracker is configured to, in response to the indication that a subscription record has changed, determine whether the current monitoring key should be changed to a new monitoring key; and

wherein the message generator is configured to, if the usage tracker determines that the current monitoring key should be changed to the new monitoring key, disable the current monitoring key at the usage monitoring node.

14 . A tangible and non-transitory machine-readable storage medium encoded with instructions for execution by a session management node for tracking usage in a subscriber network, the machine-readable storage medium comprising:

instructions for receiving, at the session management node, a usage monitoring report from a usage monitoring node, the usage monitoring report including a reported usage amount for a first monitoring key;

instructions for updating a current usage amount based on the reported usage amount;

instructions for identifying a current monitoring key; and

instructions for requesting additional monitoring from the usage monitoring node for the current monitoring key.

15 . The tangible and non-transitory machine-readable storage medium of claim 14 , wherein the current monitoring key is different from the first monitoring key.

16 . The tangible and non-transitory machine-readable storage medium of claim 14 , further comprising instructions for taking a policy action based on the current usage amount.

17 . The tangible and non-transitory machine-readable storage medium of claim 16 , further comprising:

instructions for determining a second usage amount associated with a second monitoring key; and

instructions for adding the current usage amount to at least the second usage amount to determine a total usage amount,

wherein the instructions for taking a policy action based on the current usage amount comprise instructions for taking a policy action based on the total usage amount.

18 . The tangible and non-transitory machine-readable storage medium of claim 14 , wherein the instructions for requesting additional monitoring from the usage monitoring node for the current monitoring key comprise:

instructions for determining a next threshold based on the current usage amount; and

instructions for sending a request message to the session monitoring node including the current monitoring key and the next threshold.

19 . The tangible and non-transitory machine-readable storage medium of claim 18 , further comprising:

instructions for determining a second usage amount associated with a second monitoring key; and

instructions for adding the current usage amount to at least the second usage amount to determine a total usage amount,

wherein instructions for determining a next threshold based on the current usage amount comprise instructions for determining a next threshold based on the total usage amount.

20 . The tangible and non-transitory machine-readable storage medium of claim 14 , further comprising:

instructions for receiving an indication that a subscription record has changed;

instructions for determining whether the current monitoring key should be changed to a new monitoring key; and

instructions for, if the current monitoring key should be changed to the new monitoring key:

disabling the current monitoring key at the usage monitoring node, and

setting the current monitoring key to equal the new monitoring key.