Throttling, DSCP, and 802.1p with Traffic Control

In his introductory post about the legacy Traffic Control (TC) API, Gabe discussed the host-based model that TC provides. In this post, we will see how Traffic Control APIs can be used to achieve the following for TCP/IPv4 and UDP/IPv4 traffic sent from a host: Throttle (rate-limit) outgoing traffic Add DSCP value in layer-3 (IPv4)…


Introduction to Windows QoS Traffic Control

Disclaimer: Traffic Control (TC) APIs have been marked as deprecated, and will be phased out (eventually removed) when a suitable replacement API is available. No advancements will be made to these APIs (including adding IPv6 support) in their deprecated state; however, application compatibility will be maintained until their eventual removal. Since the introduction of a…


WiFi WMM Requirements for Vista Miniport Drivers

A number of partners who author wireless drivers for Vista have asked how they can ensure their WiFi Wireless Multimedia (WMM) implementation is correct, so I thought I’d be explicit about this very important topic. To begin, read the 4-part series WiFi QoS Support in Windows Vista, which describes how Vista internally indicates a WMM…


Detecting 802.1p Priority Tags: Part 3

Parts 1 and 2 of this series discussed how to determine whether an 802.1p tag was added to traffic, and how to modify the NDIS light-weight-filter (LWF) sample driver source code to accomplish this task. We do know that you’re all very busy and not everyone is a developer, so we’ve added to the package:…


Detecting 802.1p Priority Tags: Part 2

In Gabe’s last post on detecting 802.1p priority tags, he described at a relatively high-level why it is difficult to detect a priority tag using packet tracing applications, as well as the proper way to determine whether a tag was present in a packet that was sent onto the wire (or air). In this post,…


Detecting 802.1p Priority Tags

Consider a case where a network application calls Windows QoS APIs to add a layer-2 IEEE 802.1Q UserPriority tag (almost always referred to as 802.1p) to outgoing traffic. Ascertaining whether the tag actually got added to an outgoing packet is not as simple as it seems due to the nature of how the Windows network…


The Case of Vista Multimedia Playback and Network Throughput

Mark Russinovich has a great post today on the what and how of the network/multimedia vista issue that people have recently been talking about. Amusingly enough a couple people on /. more or less figured it out, but are only modded 3 and lower. Go Figure. — Ari


Ask Perf explains how winInet is used

Ask Perf, the blog of the Enterprise Platforms Windows Server Performance Team, is spending some time explaining a bit of how WinInet/WinHTTP and their surrounding components work with each other. Go check it out!   — Ari


Receive Window Auto-Tuning on Vista.

Hi, my name is Katarzyna and I am the Program Manager within the Internet Protocols team. I have been asked a few times about the Receive Window Auto-Tuning feature on Vista and some associated issues people are having. One of the many cool new features on Windows Vista, Receive Window Auto-Tuning enables the networking stack…


OffTopic: Another way to generate XML in PowerShell

I recently needed to generate XML from PowerShell and was disappointed to see the PowerShell blog use the old ASP model of doing text insertion into the middle of a big string. It might be the tester in me, or the security training, but with some unexpected input you can easily end up with malformed…