I’ve got 2 windows 2012 servers that limit connection speed to anywhere from 1-3mBps and it seems to be related to tcp window scaling. Both servers have these settings TCP Global Parameters ———————————————- Receive-Side Scaling State : enabled Chimney Offload State : disabled NetDMA State : disabled Direct Cache Access (DCA) : disabled Receive Window … Read more
Having an issue with any large file transfer that crosses our Cisco ASA unit come to an eventual pause. Setup Test1: Server A, FileZilla Client <- 1GBPS -> Cisco ASA <- 1 GBPS -> Server B, FileZilla Server TCP Window size on large transfers will drop to 0 after around 30 seconds of a large … Read more
I have a download stream over TCP in an application (running on Win2k12). The problem is that the connection gets closed by the sender because it times out. I used wireshark to see what happens on 2 different servers (on one server it works ok, on the other it gets timed out). I have noticed … Read more
I am new to Windows networking. When people talk about TCP tuning on Windows platform, they always mention about TCP Window Size. I am wondering whether Windows uses the concept of “Socket Buffer Size”? On Windows XP, the TCP window size is fixed. We can set it using the TCPWindowSize registry value. How about Socket … Read more
I’ve been given access to a share on a Windows Server 2003 SP1 system (10.a.bbb.ccc) which is a file and printer server, and regularly large files get copied to that share. However, occasionally such a copy fails. When reproducing this issue using Robocopy (on 10.xxx.yy.zzz), I get something like 70.4% 2013/07/31 11:20:21 ERROR 64 (0x00000040) … Read more
A satellite connection generally has a RTT around 500ms. Connections generally suffer sub-optimal transfer speeds, in spite of large amounts of bandwidth because TCP acknowledgements take too long to arrive. My understanding is that a good way to address this problem with TCP connections is to set the TCP Window size to the connection speed … Read more
Facts (please identify any false statements): I have a 100 Mbps connection between two sites that are 80 ms apart This is a long fat connection that could benefit from a large TCP window size perhaps up to 100 Mbps * 0.08 sec = 1,000,000 bytes Both machines are running Windows Server 2012. “Receive window … Read more
