Citrix Systems CITRIX NETSCALER 9.3 Benutzerhandbuch
IST-Asia/Colombo
System Time: Tue Feb 22
16:50:44 2011
Last Config Changed Time: Tue Feb 22
16:48:02 2011
Last Config Saved Time: Tue Feb 22
16:48:19 2011
Done
To view the system date and time by using the
configuration utility
configuration utility
1. In the navigation pane, click System.
2. In the details pane, select the System Information tab.
3. Under System Information, view the system date and time.
Configuring TCP Window Scaling
The TCP window scaling option, which is defined in RFC 1323, increases the TCP
receive window size beyond its maximum value of 65,535 bytes. This option is required
for efficient transfer of data over long fat networks (LFNs).
receive window size beyond its maximum value of 65,535 bytes. This option is required
for efficient transfer of data over long fat networks (LFNs).
A TCP window determines the amount of outstanding (unacknowledged by the
recipient) data a sender can send on a particular connection before receiving any
acknowledgment from the receiver. The main purpose of the window is flow control.
recipient) data a sender can send on a particular connection before receiving any
acknowledgment from the receiver. The main purpose of the window is flow control.
The window size field in the TCP header is 16 bits, which limits the ability of the
sender to advertise a window size larger than 65535 ( 2^16 - 1). The TCP window scale
extension expands the definition of the TCP window by applying a scale factor to the
value in the 16 bit window size field of the TCP header. (Although RFC 1323 describes
expanding the definition to up to 30 bits, NetScaler window scaling expands the
definition of the TCP window to up to 24 bits.) The scale factor is carried in the new
TCP window scale field. This field is sent only in a SYN packet (a segment with the SYN
bit on)
sender to advertise a window size larger than 65535 ( 2^16 - 1). The TCP window scale
extension expands the definition of the TCP window by applying a scale factor to the
value in the 16 bit window size field of the TCP header. (Although RFC 1323 describes
expanding the definition to up to 30 bits, NetScaler window scaling expands the
definition of the TCP window to up to 24 bits.) The scale factor is carried in the new
TCP window scale field. This field is sent only in a SYN packet (a segment with the SYN
bit on)
To fit a larger window size value into the 16-bit field, the sender right shifts the value
by the number of bit positions specified by the scale factor. The receiver left shifts the
value by the same number of positions. Therefore, the actual window size is equivalent
to:
by the number of bit positions specified by the scale factor. The receiver left shifts the
value by the same number of positions. Therefore, the actual window size is equivalent
to:
(2^<scale factor>) * <received window size>.
Before configuring window scaling, make sure that:
w
You do not set a high value for the scale factor, because this could have adverse
effects on the NetScaler and the network.
effects on the NetScaler and the network.
w
You have enabled selective acknowledgement (SACK).
Chapter 5
Advanced Configurations
130