3Com Switch 4500 Family Manual page 900

Parameters
size: size of IPv6 TCP receiving/sending buffer in KB (kilobyte), in the range of 1 to 32.
Description
Use the tcp ipv6 window command to set the size of IPv6 TCP receiving/sending buffer.
Use the undo tcp ipv6 window command to restore the size of IPv6 TCP receiving/sending buffer to
the default.
By default, the size of the IPv6 TCP packet buffer is 8 KB.
Examples
# Set the size of IPv6 TCP receiving/sending buffer to 4 KB.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] tcp ipv6 window 4
1-30