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Implement IETF QUIC into ATS Core.

Design Doc

The UDP core and QUIC (It explain how the UDP core works and how the UDPPacket enters the QUIC stack.)

Data Flow (draft-05 : Second Implementation)

QUIC Connection/Stream - ATS Client Session/Transaction mapping

I/O between HttpSM and QUICNetVC



Please label issues and pull-requests with "QUIC".

Branching Rules


  • quic-latest : latest branch
  • master: draft-29 (currently)

Development Rules


Please send Pull-Requests to "quic-latest" branch until it merged into master branch


Use Catch as Unit Test Framework. The header file is under tests/include.

How to build

Build an SSL library

ATS now supports 4 variation of SSL libraries. Pick one from below and build it. 


Official BoringSSL works without patches.

These commits below work, and recent commits would probably work as well.

cbae965ca03825d517efe98cf7b8812584cab4a0 (BoringSSL API version 9)

88024df12147e56b6abd66b743ff441a0aaa09a8 (BoringSSL API version 10)

Please note that the support for BoringSSL API version 9 may be removed without notice in the future.

OpenSSL (quictls/openssl) [RECOMMENDED]

They also have branches based on OpenSSL 3.0 but we haven't fully supported it.

$ git clone --depth 1 --branch OpenSSL_1_1_1j+quic
$ cd openssl
$ ./config --prefix=/PATH/TO/THE/OPENSSL
$ make
$ make install

OpenSSL (tatsuhiro-t/OpenSSL_1_1_1g-quic-draft-32) [OBSOLETE]

This is ngtcp2 developer's customized version.

OpenSSL (akamai/master-quic-support) [INCOMPATIBLE]

This used to work, but it's incompatible now because it's based on OpenSSL master branch.

This is the branch used for .

Build ATS (quic-latest branch)

The requirements are the same as master branch : Installing From Source Code

$ git clone --depth 1 --branch quic-latest
$ cd trafficserver
$ ./configure --prefix=/PATH/TO/ATS --with-openssl=/PATH/TO/SSL_LIBRARY --enable-debug
$ make
$ make install


Configuration files are located in the /PATH/TO/THE/ATS/etc/trafficserver/.

The detail is documented here, but below is the essential settings.

  • records.config
# run 1 UDP thread at least
CONFIG proxy.config.udp.threads INT 1
# open server port for quic
CONFIG proxy.config.http.server_ports STRING 4433:quic
# enable debug log if you want
CONFIG proxy.config.diags.debug.enabled INT 1
CONFIG proxy.config.diags.debug.tags STRING quic
> CONFIG proxy.config.udp.threads INT 1
< CONFIG proxy.config.http.server_ports STRING 8080 8080:ipv6
> CONFIG proxy.config.http.server_ports STRING 4433:quic
< CONFIG proxy.config.diags.debug.enabled INT 0
< CONFIG proxy.config.diags.debug.tags STRING http|dns
> CONFIG proxy.config.diags.debug.enabled INT 1
> CONFIG proxy.config.diags.debug.tags STRING quic

  • ssl_multicert.config
    •  Please use absolute path to the cert and private key until Issue #2358 is fixed.
dest_ip=* ssl_cert_name=/PATH/TO/THE/CERT ssl_key_name=/PATH/TO/THE/PRIVATE/KEY/OF/CERT
  • remap.config
    • Remap request to origin server.
map /



Patches has additional patch to make debug logs readable.

QUIC specific configurations

Following docs will be moved to

Please note that current name of configurations and default values might be changed before merged in to master branch.


CONFIG proxy.config.quic.no_activity_timeout_in INT 30

   Specifies how long Traffic Server keeps QUIC connections to clients open if a transaction stalls.

How to test

Third-party tools

There is a script that builds third-party tools in the repo. It builds h2load and curl with HTTP/3 support. An HTTP/3 client under ngtcp2/example is also useful when you want to check details.


The quic-latest branch has client implementation called "traffic_quic" for test.

// draft-17

$ traffic_quic -h
Usage: traffic_quic [--SWITCH [ARG]]
  -a, --addr              str Address
  -o, --output            str             Write to FILE instead of stdout
  -p, --port              str   4433      Port
  -P, --path              str   /         Path
  -T, --debug             str   quic|vv.. Vertical-bar-separated Debug Tags
  -c, --close             on    false     Enable connection close excercise
  -h, --help                              Print usage information
  -V, --version                           Print version string
      --run-root                          using TS_RUNROOT as sandbox

client specific configurations

traffic_quic loads records.config which is used by traffic_server.


# Enable Version Negotiation Exercise
CONFIG proxy.config.quic.client.vn_exercise_enabled INT 1

# Enable Connection Migration Exercise
CONFIG proxy.config.quic.client.cm_exercise_enabled INT 1

# Enable TLS session resumption
CONFIG proxy.config.quic.client.session_file STRING session.bin 

These configurations can be overridden by a corresponding environment variable like other configurations in records.config.

e.g. Access with version negotiation exercise

$ PROXY_CONFIG_QUIC_CLIENT_VN_EXERCISE_ENABLED=1 traffic_quic -a -p 4433 -P /en/latest/

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