Add missing networking runtime configuration switches by Copilot · Pull Request #52297 · dotnet/docs

Copilot · 2026-03-13T17:15:07Z

The networking runtime config page (docs/core/runtime-config/networking.md) only documented two settings despite many more being configurable. This adds the missing switches, verified against the dotnet/runtime source.

Added sections

Section	Setting name	Notes
HTTP/3 protocol	`System.Net.SocketsHttpHandler.Http3Support`	Enabled by default starting in .NET 7
HTTP/2 dynamic window scaling	`System.Net.SocketsHttpHandler.Http2FlowControl.DisableDynamicWindowSizing`	`true` disables the algorithm; enabled by default
HTTP/2 stream receive window size	`DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_FLOWCONTROL_MAXSTREAMWINDOWSIZE`	Env var only; default 16 MB, min 65,535
HTTP/2 stream window scale threshold	`DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_FLOWCONTROL_STREAMWINDOWSCALETHRESHOLDMULTIPLIER`	Env var only; default 1.0
HTTP activity propagation	`System.Net.Http.EnableActivityPropagation`	Distributed tracing (`traceparent`) for OpenTelemetry; enabled by default
Pending connection timeout on request completion	`System.Net.SocketsHttpHandler.PendingConnectionTimeoutOnRequestCompletion`	Default 5,000 ms
Proxy pre-authentication	`System.Net.Http.SocketsHttpHandler.ProxyPreAuthenticate`	Disabled by default
Maximum connections per server	`System.Net.SocketsHttpHandler.MaxConnectionsPerServer`	Default unlimited
Socket inline completions	`DOTNET_SYSTEM_NET_SOCKETS_INLINE_COMPLETIONS`	Env var only; disabled by default
Socket thread count	`DOTNET_SYSTEM_NET_SOCKETS_THREAD_COUNT`	Env var only
IPv6	`System.Net.DisableIPv6`	—
TLS session resumption	`System.Net.Security.DisableTlsResume`	Enabled by default
Server AIA downloads	`System.Net.Security.EnableServerAiaDownloads`	Disabled by default
QUIC configuration caching	`System.Net.Quic.DisableConfigurationCache`	Caching enabled by default
App-local MsQuic	`System.Net.Quic.AppLocalMsQuic`	Windows only; AppContext only
HttpListener kernel response buffering	`System.Net.HttpListener.EnableKernelResponseBuffering`	Windows only; AppContext only; disabled by default

Accuracy notes

The HTTP/2 stream receive window size and scale threshold are env-var only — the runtime uses ParseInt32/DoubleEnvironmentVariableValue rather than QueryRuntimeSettingSwitch, so no runtimeconfig.json key exists for these.
The DisableDynamicWindowSizing flag defaults to false (algorithm enabled). Setting to true disables it.
The UseSocketsHttpHandler setting was deliberately excluded as it was previously removed from the docs (see Remove/update version 3.1 usage #40601) since it's no longer available in .NET 5+.
The App-local MsQuic and HttpListener kernel response buffering settings are AppContext-only (no environment variable equivalent).
TLS and QUIC switches verified against SslStream.Protocol.cs, MsQuicApi.cs, MsQuicConfiguration.Cache.cs, and HttpListener.Windows.cs in the dotnet/runtime source.

Original prompt

This section details on the original issue you should resolve

<issue_title>Add missing networking switches</issue_title>
<issue_description>

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

ID: bfcfc815-a1d9-fcf3-ec45-0379ca35412d

Version Independent ID: d778f279-fc56-01e8-3882-b452db0536ed

Content: Networking config settings - .NET Core

Content Source: docs/core/run-time-config/networking.md

Product: dotnet-core

GitHub Login: @gewarren

Microsoft Alias: gewarren</issue_description>

Comments on the Issue (you are @copilot in this section)
@gewarren Page views are low-ish. Lowering the priority on this.

Fixes Add missing networking switches #20770

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

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docs/core/runtime-config/networking.md	docs/core/runtime-config/networking

Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

docs/core/runtime-config/networking.md

rzikm · 2026-03-16T07:34:00Z

There are more network switches (added since the issue was filed probably), The non-HTTP ones should be visible in dotnet/runtime#125385 (that PR only moves the definition, does not add/remove)

docs/core/runtime-config/networking.md

Co-authored-by: Genevieve Warren <24882762+gewarren@users.noreply.github.com>

… remove UseSocketsHttpHandler section Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

BillWagner · 2026-03-16T14:14:14Z

@copilot Address this comment: #52297 (comment) by adding the additional switches.

BillWagner · 2026-03-16T14:15:42Z

@rzikm @gewarren

The additions show the default and some minimum allowed values. Should all the integer and float values include a valid range, the max as well as the min?

…nd HttpListener Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

Copilot · 2026-03-16T14:23:01Z

@copilot Address this comment: #52297 (comment) by adding the additional switches.

Added in c9d8bdb. The new sections cover the additional switches from the runtime source (verified against GlobalHttpSettings.cs, SslStream.Protocol.cs, MsQuicConfiguration.Cache.cs, MsQuicApi.cs, and HttpListener.Windows.cs):

HTTP:

Pending connection timeout on request completion (System.Net.SocketsHttpHandler.PendingConnectionTimeoutOnRequestCompletion)
Proxy pre-authentication (System.Net.Http.SocketsHttpHandler.ProxyPreAuthenticate)
Maximum connections per server (System.Net.SocketsHttpHandler.MaxConnectionsPerServer)

TLS/SSL:

TLS session resumption (System.Net.Security.DisableTlsResume / DOTNET_SYSTEM_NET_SECURITY_DISABLETLSRESUME)
Server AIA downloads (System.Net.Security.EnableServerAiaDownloads / DOTNET_SYSTEM_NET_SECURITY_ENABLESERVERAIADOWNLOADS)

QUIC:

QUIC configuration caching (System.Net.Quic.DisableConfigurationCache / DOTNET_SYSTEM_NET_QUIC_DISABLE_CONFIGURATION_CACHE)
App-local MsQuic, Windows only (System.Net.Quic.AppLocalMsQuic, AppContext only)

HttpListener:

Kernel response buffering, Windows only (System.Net.HttpListener.EnableKernelResponseBuffering, AppContext only)

rzikm · 2026-03-16T17:11:42Z

@rzikm @gewarren

The additions show the default and some minimum allowed values. Should all the integer and float values include a valid range, the max as well as the min?

@MihaZupan would probably know,

cc @dotnet/ncl

MihaZupan · 2026-03-16T19:05:23Z

Looking at the list, that leaves:

DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_FLOWCONTROL_MAXSTREAMWINDOWSIZE
- Already documented as Integer (default: 16 MB; minimum: 65,535)
- No real max. Increasing it would only be beneficial in a network that's both high throughput and high latency.
DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_FLOWCONTROL_STREAMWINDOWSCALETHRESHOLDMULTIPLIER
- Documented as Float (default: 1.0; minimum: 0)
- No real max. Increasing it too much would just effectively cap the max throughput of an individual request relative to your network throughput.
- Feels more like an option exposed for our own testing than for regular users to modify
DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_PENDINGCONNECTIONTIMEOUTONREQUESTCOMPLETION
- Documented as Integer (default: 5000)
- -1 is a valid minimum value with the meaning of "forever" - it's effectively the max.
- 0 means "immediately cancel". There's no real max (other than int32), but really high values are pointless in practice.
DOTNET_SYSTEM_NET_SOCKETS_THREAD_COUNT
- Realistic values are [1, ProcessorCount], but we don't always enforce that so if the user hates performance they're free to set it higher :)

BillWagner · 2026-03-17T15:59:49Z

@copilot

Make changes based on this comment: #52297 (comment)

Note that for some switches, there is a practical limit and a different allowed limit. Further, note that some of the switches aren't generally used by most developers. Modulate your edits to point distinguish hard limits, practical advice, and note where switches aren't intended for general developer use.

…r guidance Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

Copilot · 2026-03-17T16:02:33Z

@copilot

Make changes based on this comment: #52297 (comment)
...

Updated in b205a6d based on @MihaZupan's feedback:

Stream window scale threshold: Added a note that this is intended for advanced diagnostics/internal tuning and most developers don't need it. Clarified that values much above the default progressively limit per-request throughput.
Stream receive window size: Clarified that values below 65,535 are clamped (not rejected), and noted there's no hard upper limit — only beneficial on high-throughput, high-latency networks.
Pending connection timeout: Documented the -1 (wait indefinitely) and 0 (cancel immediately) special values explicitly. Noted there's no hard upper limit.
Socket thread count: Documented the practical range as [1, ProcessorCount], noted that values outside this range aren't rejected, and added a note that this setting is for extreme load scenarios — most developers don't need it.

BillWagner

This LGTM, and is ready for final review.

Copilot

Pull request overview

Updates the .NET runtime networking configuration documentation to cover additional runtimeconfig and environment-variable switches that control HTTP, socket, TLS, QUIC, and HttpListener behaviors.

Changes:

Adds documentation for missing networking runtime configuration switches (HTTP/3, HTTP/2 flow control, diagnostics propagation, proxy behavior, socket settings, IPv6, TLS, QUIC, and HttpListener).
Refreshes article metadata (ms.date) and adds AI usage disclosure (ai-usage).
Improves wording in the existing SPN creation section.

docs/core/runtime-config/networking.md

+| **runtimeconfig.json** | `System.Net.Http.SocketsHttpHandler.ProxyPreAuthenticate` | `false` - disabled (default)<br>`true` - enabled |
+| **Environment variable** | `DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_PROXYPREAUTHENTICATE` | `0` - disabled (default)<br>`1` - enabled |


docs/core/runtime-config/networking.md

+| | Setting name | Values |
+| - | - | - |
+| **runtimeconfig.json** | `System.Net.SocketsHttpHandler.Http3Support` | `false` - disabled <br>`true` - enabled |
+| **Environment variable** | `DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_HTTP3SUPPORT` | `0` - disabled<br/>`1` - enabled |


docs/core/runtime-config/networking.md

+| **runtimeconfig.json** | `System.Net.Http.UsePortInSpn` | `true` - include port number in SPN, for example, `HTTP/host:port`<br>`false` - don't include port in SPN, for example, `HTTP/host` |
+| **Environment variable** | `DOTNET_SYSTEM_NET_HTTP_USEPORTINSPN` | `1` - include port number in SPN, for example, `HTTP/host:port`<br>`0` - don't include port in SPN, for example, `HTTP/host` |


docs/core/runtime-config/networking.md

+
+## QUIC configuration caching
+
+Disables caching of MsQuic configuration objects. When enabled (default), the system caches and reuses configuration objects across connections, which reduces the overhead of TLS and QUIC setup for repeated connections with the same parameters.


docs/core/runtime-config/networking.md

+
+## TLS session resumption
+
+Disables TLS session resumption for <xref:System.Net.Security.SslStream>. Session resumption allows TLS reconnections to skip a full handshake by reusing previously negotiated session parameters, which reduces latency.


Initial plan

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Copilot AI assigned Copilot and BillWagner Mar 13, 2026

Copilot started work on behalf of BillWagner March 13, 2026 17:15 View session

Add missing networking runtime configuration switches to networking.md

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Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add missing networking switches~~ Add missing networking runtime configuration switches Mar 13, 2026

dotnet-policy-service bot added the dotnet-fundamentals/svc label Mar 13, 2026

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Copilot started work on behalf of BillWagner March 16, 2026 14:05 View session

Address PR review feedback: simplify HTTP/3 description, fix br tags,…

bfc0bc9

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Copilot started work on behalf of BillWagner March 16, 2026 14:14 View session

Add additional networking runtime config switches: HTTP, TLS, QUIC, a…

c9d8bdb

…nd HttpListener Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>

Copilot finished work on behalf of BillWagner March 16, 2026 14:24

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Refine numeric switch descriptions with practical limits and develope…

b205a6d

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		\| runtimeconfig.json \| `System.Net.Http.SocketsHttpHandler.ProxyPreAuthenticate` \| `false` - disabled (default)<br>`true` - enabled \|
		\| Environment variable \| `DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_PROXYPREAUTHENTICATE` \| `0` - disabled (default)<br>`1` - enabled \|


		## QUIC configuration caching

		Disables caching of MsQuic configuration objects. When enabled (default), the system caches and reuses configuration objects across connections, which reduces the overhead of TLS and QUIC setup for repeated connections with the same parameters.


		## TLS session resumption

		Disables TLS session resumption for <xref:System.Net.Security.SslStream>. Session resumption allows TLS reconnections to skip a full handshake by reusing previously negotiated session parameters, which reduces latency.

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