Adapter Setting

[MagikMark]

Hi Philip!


1. May I ask if the ff settings are dependent or has direct performance correlation with my
ISP servers:

LSO
Chimney Offload
RSC
Time Stamp

Meaning, if I have different settings than that off my ISP, it may cause connectivity problem

How do we know which settings are appropriate for your ISP? Trial and Error?


2. Windows now has Auto tuning level. It changes the size of the TCP receive window as it sees fit. May I ask then why TCP 123 Time stamp still present?
This setting if I'm correct is also responsible for windows scaling which is automatically adjusted by windows. Looks like redundancy

Thanks

[Philip]

1. No. In general, unlike devices with different subsets of those settings will negotiate at connection time a valid subset of features that work.


2. Most TCP settings have to be compatible with older versions of the protocol, so they can communicate with/through older devices, imagine all the routers/switches, etc. When TCP1323 options were added to TCP, there was no room in the headers (20-byte IP, 20-byte TCP), so they extended the header size keeping the original 20-bytes, then padding the payload with more options. Still older devices could communicate, even if they did not support RFC 1323.

Auto-scaling in Windows is internal feature. It figures out the current bandwidth-delay and advertises a suitable TCP Receive Window size. If autotuning is enabled, TCP1323 options are always enabled. You still have to specify the acceptable TCP Window size, and that's where the Windows auto-tuning algorithm comes in, deciding on a size based on bandwidth, packet loss, delay.

I hope this helps.