Why should asynchronous processing not be done for ALE classify marked packets?

Hi,
I have 2 long pending doubts on ALE classify:

  1. I understand ALE classify and its processing but do not understand “A callout driver must not perform asynchronous processing of packets that require ALE classify processing at an incoming (inbound) transport layer…”. statement.

If ALE classify marked packets are processed asynchronously then what would be side effect in whole traffic processing? What should be side effect on Windows firewall/System components and other 3rd party WFP drivers?

  1. Which component sets ALE classify flag in packets and how is it decided?
    Could you please explain me?

Regards,
Anand Choubey

P.S.: I asked this question is based on below paragraph from http://msdn.microsoft.com/en-us/library/windows/hardware/ff570203(v=vs.85).aspx

INBOUND_TRANSPORT Layers
A callout driver must not perform asynchronous processing of packets that require ALE classify processing at an incoming (inbound) transport layer (FWPS_LAYER_INBOUND_TRANSPORT_V4 orFWPS_LAYER_INBOUND_TRANSPORT_V6). Doing this can interfere with flow creation. When WFP calls the classifyFn callout function at an incoming transport layer, it sets theFWPS_METADATA_FIELD_ALE_CLASSIFY_REQUIRED flag for those packets that require ALE classify processing. A callout driver should permit such packets from an INBOUND_TRANSPORT layer and should defer processing them until they reach an ALE_RECV_ACCEPT layer.

I corrected my typo here:
If ALE classify marked packets are NOT processed asynchronously …