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Microsoft Promising Web Transport Improvements with Windows 10 and Windows Server 2016 'Redstone' Releases

• By Kurt Mackie
• 07/20/2016

Microsoft's coming Windows 10 and Windows Server 2016 upgrades will add some Transmission Control Protocol (TCP) improvements, company announced this week.

The improvements will be available when Microsoft delivers its code-named "Redstone" updates to those client and server operating systems. The Redstone updates (called "anniversary update" in the case of Windows 10) are expected to get released sometime this summer.

Microsoft is promising that organizations could see better networking with the updates, including Internet traffic latency reductions and improved resilience against pack loss problems. It's a general promise, and IT pros perhaps will need to put on their "TCP hats" to appreciate it. In addition, they'll have to turn on some settings for client and server since some improvements won't be enabled by default. Many of the improvements affect short Web transfers via round-trip time (RTT) improvements, but there also are start speed improvements.

Here are the five TCP improvements coming with the Redstone releases, per Microsoft's announcement:

• TCP Fast Open (TFO)
• Initial Congestion Windows 10 (ICW10)
• TCP Recent ACKnowledgment (RACK)
• Tail Loss Probe (TLP)
• TCP Low Extra Delay Background Transport (LEDBAT)

TFO reduces one RTT compared with a standard TCP arrangement. Microsoft is promising that the addition of TFO technology will improve latency issues for short Internet transfers, especially for "busy servers that deliver many small objects to the same clients."

The TFO technology will be part of the Windows 10 anniversary update release by default. It will be disabled by default in the Microsoft Edge browser, but Microsoft has plans to make it a default setting in both the Edge and Internet Explorer browsers in future updates. The Windows Server side will have the TFO feature turned off by default.

ICW10 is a Windows start speed improvement. The "ICW" term refers to "how much data can be sent in the first RTT," Microsoft explained. It affects "small object transfers over the Internet," and Microsoft is promising that the coming ICW10 approach will be capable of transferring objects "up to twice as quickly as ICW4," which is the present Windows networking approach.

To use ICW10, IT pros will have to use "templates (netsh) or set-nettcpsetting (PowerShell)" cmdlets to make the needed configuration changes.

RACK is designed to provide improved packet loss detection by tracking transmission times. In contrast, the standard approach counts "duplicate ACKnowledgments to detect missing packets."

The RACK technology only works when the RTT is at least 10 milliseconds for the Windows client and server. It gets set up using TCP templates, but it's a default element for both client and server.

Last and somewhat least is LEDBAT. Microsoft described it as "a background transport that does not interfere with other TCP connections." It will only tap unused bandwidth, and will reduce its bandwidth use to "prevent interference." However, LEDBAT has to be enabled using an "experimental Windows TCP Congestion Control Module" and Microsoft hasn't yet published the documentation to implement it.