Sorry this is a bit non-cisco but was wondering if anyone could help?
I have a large file download from a windows server to my PC. The performance is grim for some reason, but thats not what I am worried about.
So, my PC lets just say sends an ack back to the server after it recieved a packet from the server.
In the ACK, it advertises the window size of 64k back to the server as follows :-
Transmission Control Protocol, Src Port: 1293 (1293), Dst Port: microsoft-ds (445), Seq: 75469, Ack: 5954634, Len: 0
Source port: 1293 (1293)
Destination port: microsoft-ds (445)
Sequence number: 75469 (relative sequence number)
Acknowledgement number: 5954634 (relative ack number)
Header length: 20 bytes
Flags: 0x10 (ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 64512
Checksum: 0xac2f [incorrect, should be 0xb9d3 (maybe caused by "TCP checksum offload"?)]
[Good Checksum: False]
[Bad Checksum: True]
[This is an ACK to the segment in frame: 7686]
[The RTT to ACK the segment was: 0.000007000 seconds]
BUT, the server only every sends two 1460 packets to me before I ack back to the server and the cycle continues.
Could the server not send me up to 64k of data before I need to ack back to the server? Why am I ack'ing back after every two full sized packets?
Can anyone help?