Hardware and Software Requirements - Trading Technologies

Registry Settings (Windows XP)
Table 1:
Registry Setting TT Machine Description
ArpCacheLife
These are explanations of the additional NIC settings that are implemented per TT’s recommendations.
ArpCacheMin-
ReferencedLife
Tcp1323Opts
EnableTCPA
EnableRSS
EnableTCPChimney
Server Machines,
Client Machines
Server Machines,
Client Machines
Server Machines,
Remote Hosts,
WAN Routers
Server Machines
Server Machines
Server Machines
This sets the timeout for unused entries in the OS ARP
Cache. By default, this key does not exist but is set to
two minutes. TT sets this to one (1) hour.
This sets the timeout for all entries in the OS ARP
Cache. By default, this key does not exist but is set to
10 minutes. TT sets this to two (2) hours.
This allows a TCP receive window of larger than 64k
to be advertised; it will only be seen during the SYN
and will show up as a Windows Scaling multiplication
factor. This is used when calculating the correct TCP
Receive Window for a WAN connection.
This is Net DMA NetDMA and it allows for a Direct
Memory Access (DMA) engine on the Peripheral
Component Interconnect (PCI) bus. This does not
work if RSS and TCPChimney are turned off, but Microsoft
recommends disabling it.
This toggles Receive Side Scaling. Receive Side Scaling
only works on multi-processor boxes and allows
the incoming data to be processed across multiple
CPUs. TT turns this off as it causes out of order packets,
duplicate packets, or dropped data. This really only
applies to TCP.
This allows the OS to offload the TCP stack to the
NIC. This is more efficient in that it allows the NIC
CPU to process the TCP data and only pass up what is
required. (This is only good in a streaming environment.)
TT's data is small packets all with Push Bit set
which means TT treats the TCP data more like a
Packet-based Protocol - each packet is passed up to the
applications. This is not an efficient use of offloading
and does cause extra latency.