How does a PacketShaper behave when window scaling is used?

Products

• PacketShaper

Issue/Introduction

The PacketShaper does support window scaling, so the shaping functionality will work fine.

The PCAP's window size data indicates too small of a value when you take the PCAP. There are two possibilities:

• You didn't start PCAP at the initial TCP sequence. You need the initial TCP sequence packet to get the correct calculated value.
• You are using old PCAP software. Old versions of WireShark will not display the calculated window size, but instead will display the window size without the scale factor.

As an example, if the scale factor is 3, and the packet capture is showing a window size of 365, it means the window size is 365 * 2^3 = 365 * 8, or 2920 bytes.

For WireShark to show the real window size (window size * scaling factor), set  Edit / Preference / Protocols / TCP / Relative sequence numbers and window scaling.