BITS Request Packets

Request packets describe client requests. There can be only one outstanding request at any given time; you must receive an Ack for the current request from the server before sending another request.

The following table lists the request packets sent to the BITS server for upload and upload-reply jobs. The table lists the packets in the typical sequence they are sent to the server.

Request packetPurpose
Ping Establishes a connection and negotiates security with the server.
Create-Session Requests an upload session with the BITS server.
Fragment Sends a fragment of the file to the BITS server. The number of fragment requests sent depends on the fragment size you choose and the size of the upload file.
Close-Session Ends the file upload session with the BITS server.
Cancel-Session Ends the file upload session with the BITS server. Typically, you send the Cancel-Session packet if the user canceled the job.


The Ping packet is optional. Instead of sending a Ping packet, you can use the Create-Session packet to establish a connection and negotiate security. However, it is more efficient to use the Ping packet for this purpose.