Quic and the future of Internet transmission

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translate ：Alex Technical review ： Liu Lianxiang This article is from Compira Labs, The author is Ravid Hadar.

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QUIC

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When the last century 70 years TCP When it was invented , I don't think anyone would have expected 50 Years later we are still using it . But the truth is , We are still using TCP.

In the past few decades ,TCP Continuous development , And added reliable data transmission 、 flow control 、 Congestion control and other related characteristics . But many researchers and practitioners, including myself, believe that TCP At the end of the road . since TCP Since its invention , The Internet has become a very important part of social life , But unfortunately ,TCP Not keeping pace with the times to meet growing demand .

But the encouraging news is , In place of TCP aspect , There is one of the most important “ The candidate ”—— It can make Internet transmission continue to develop , And solve many problems that have plagued the Internet for many years . say concretely , This may replace TCP The agreement is called QUIC, People are right. QUIC I am excited about the appearance of . But is this excitement justified , We will explain in a future article . In this article, we will learn about inventions in the future QUIC Why and QUIC Users of .

What is? QUIC? QUIC It's a universal 、 Security 、 Multiplex transport layer new network protocol . Its purpose is to replace TCP（ At present, it is the mainstream protocol for data transmission on the Internet ）.2012 year ,QUIC The agreement was signed by Jim Roskind Development .2013 year ,QUIC Officially announced . 2015 year ,QUIC Be submitted to IETF Standardize , But until six years later , That is to say 2021 year 5 month ,IETF Just released the first version of standardized QUIC, Was named RFC 9000. meanwhile ,IETF It also publishes and uses QUIC Of HTTP/3 Standardized version . QUIC Absorbed a lot of and TCP Similar properties , also TLS encryption , Place them in UDP In the application layer above the transport .

Why QUIC？

although TCP already “ Valiantly ” Years of service , But it may well have come to an end . It was originally designed for the wired internet , I never thought that today's wireless Internet would develop to such capacity and scale . Many experts know that , It can not adapt to the development of today's Internet . and QUIC The emergence of can make the network faster 、 More efficient 、 More secure , And most importantly , Can continue to develop .

stay QUIC Before appearance ,TCP The main alternative to UDP. In short ,TCP Provides reliable internet transmission , The data transmission can be ensured , and UDP Provides faster 、 But not reliable transmission .QUIC The purpose of is to combine TCP The best features and UDP Transport layer .

TCP The main limitations of include ：

• TCP It only defines 40 Optional bits of bytes , And almost all of them are filled . The result is , There is no place for new features .
• Many middleware （ Such as firewalls ） hypothesis TCP Packets will be constructed in a certain way . If the packets are too different from their expectations , Will be rejected or delayed , This makes TCP The agreement is almost impossible to develop .
• because TCP Implement in the kernel , So anything TCP The updates transmitted need to be modified by the new kernel . For some companies with relatively old infrastructure , It takes years to adopt new features .
• TCP The transport layer. , No built-in encryption （ namely TLS）, So it needs to add . As a result, it takes a long time to establish a secure connection , And some of them go through TCP Data transmitted （ Such as packet header ） Not encrypted , Thus creating security vulnerabilities .

QUIC and HTTP/3 Used together to replace HTTP/1（ or 2） and TCP The combination of , And solution TCP Some known problems caused by the protocol .

QUIC How to solve TCP The challenge ？

First , stay UDP build QUIC The advantages of this pragmatic decision are quite obvious .UDP Widely deployed on the Internet , So there is no need to define the transport layer from scratch （ Such as starting from scratch , It may take decades ）.

Compare with TCP,UDP It costs a lot less , This feature makes it faster 、 Simpler and more efficient . But it has a major flaw , That is the lack of reliability .UDP There is no way to ensure that every packet sent through it is transmitted , There is no way to ensure that packets are sent to the receiver in the exact order .

QUIC Inherited TCP Characteristics of , Build them on UDP above , And added more features .TCP The transport layer. ,TLS and HTTP2 The application layer above it ,QUIC It includes both application layer and transport layer mechanisms . therefore , Its purpose is to replace TCP Transport layer .

QUIC Use UDP As the underlying transport protocol , At the same time, the built-in TLS encryption , And combined TCP Reliability related characteristics of .QUIC At application level （ That's user space ） Get further implementation . therefore , There is no need to update the kernel , You can make a lot of changes .

Who is using QUIC？

As a general transport protocol ,QUIC It can be used in many Internet-based workflows , But the first step in deployment is to move web browsing to QUIC, Because the most direct benefit it brings is based on HTTPS Of Web Browse .

As TCP Successor ,QUIC Only with HTTP/3 Use it together . In order to use the protocol , Both the client and the website need to support it , But because only a few websites use HTTP/3, So this also becomes QUIC The agreement was widely adopted as an obstacle on the road . according to W3Tech[1], end 2021 year 10 month 2 Japan , about 35% Our website is still in use HTTP/1; about 45% Our website has moved to HTTP/2, And only about 20% Your website is using HTTP/3 and QUIC.

end 2021 In the middle of ,QUIC Occupy the majority of Internet traffic 12%. Google was the first （ And the most famous ） use QUIC The company of the agreement （ No surprise , After all QUIC The agreement was developed by Google employees ）. In its ecology , Google has its own servers 、 Applications 、 Services and clients , So it's easy to implement QUIC, And migrate many applications to new frameworks .30% Of YouTube Traffic has shifted to QUIC.

Next is Facebook（ Renamed now Meta）, It has already 70% The traffic has migrated to QUIC.Facebook and Instagram Mobile applications are already being used to the maximum extent QUIC.

This is it. QUIC The status quo of protocol adoption . Microsoft only uses a small amount of traffic QUIC; In the field of streaming media , Only YouTube and Facebook Live Support QUIC. Streaming video is close to 80% Of Web Traffic , Most still use TCP. Streaming media giant Netflix and Amazon Prime No support QUIC. however , Microsoft has made it VPN Products from TCP Migrate to QUIC Tendencies [2].

At present, we support QUIC The ecology of includes ：

• browser ：Chrome（ Default ）、Edge、Firefox、Safari And other defaults TCP Browser （ But will QUIC As an optional option ）.
• application ： All apps from Google , Such as Gmail and YouTube;Facebook Application ;Uber.
• The server /CDN：Akamai、 Microsoft 、Apple、 Google 、Cloudflare、Fastly、Caddy and NetApp. Some of them CDN It has been verified QUIC The implementation of the , But almost all of their traffic is still in use TCP.
• Web The server ：LiteSpeed、H20、Ngnix and Apache.
• Load Balancer ：LiteSpeed and F5 BIG-IP.
• Technical community project ： be based on chromium Realized libquic、 Reverse proxy （ Acting as a reverse proxy server Docker Mirror image ）.
• programing language ：Go（quic-go）、Quic.NET（C#）.

As you can see , be based on Web The infrastructure of has begun to QUIC transfer , But in most cases ,QUIC Not the default option yet , And some big companies still don't support QUIC.

Why did it take so long to launch QUIC？

QUIC It is still a new standard , Its aim is to redesign many aspects of the Internet . Standardizing on so many features takes time . although QUIC stay 2013 First submitted to IETF, But it was not until the 2021 year 5 It was officially launched in January , So it is still not fully supported by different ecosystems .

QUIC The time between initial publication and formal standardization is too long , This has led many vendors to develop their own versions of the protocol . They are getting the original release QUIC after , Build your version on it . But the protocols they use are different from the final and official versions . therefore ,QUIC There are many different versions , Some of these do not support the official version of the required features , And different manufacturers need time to adjust their versions to be the same as 2021 The official version is consistent . We can see , This transition is still at an early stage , For example, I realized my own gQUIC Version of Google is migrating to IETF released QUIC edition .

in other words , More extensive QUIC Adoption still faces many challenges , Including enterprise safety regulations on QUIC Acceptance of 、 Support TCP The fallback request and the fact that the specification is still fairly basic . I'll explain some of these challenges in more detail in subsequent articles .

QUIC Have the potential of Internet transmission

TCP It is a protocol designed for the past Internet era , It cannot be applied to the Internet today , and QUIC The purpose of is to solve TCP Many of the problems of , Make the Internet more secure 、 More sensitive and can be continuously developed . It's important to remember that , We are still in QUIC Early stages of protocol deployment , The next few years will see if it can be completed as TCP The successor's mission .QUIC Your potential is not just to be TCP alternatives , Some of its standardization measures on real-time protocol may make it replace the real-time communication protocol used in video conferencing and cloud games （ Such as WebRTC）.

notes ：

[1]https://w3techs.com/technologies/details/ce-http3

[2]https://techcommunity.microsoft.com/t5/storage-at-microsoft/smb-over-quic-is-now-in-public-preview/ba-p/2482964

thank ：

This paper has been approved by the author Ravid Hadar Authorized translation and release , Hereby thank .

Link to the original text ：

https://www.compiralabs.com/post/quic-and-the-future-of-internet-transport/

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It lasted five years. ,HTTP/3 Finally standardized ！

Yesterday, ,IETF QUIC and HTTP Members of the working group Robin Mark Announce on twitter , after 5 year ,HTTP/3 It is finally standardized as RFC 9114！ For details, see ：

https://www.rfc-editor.org/rfc/rfc9114.html

meanwhile , HTTP/2 Also updated with new RFC 9113, For details, see ：

https://www.rfc-editor.org/rfc/rfc9113.html

Robin writes , Newly released HTTP/3 The standard will be RFC 9204（QPACK header Compress ）  and RFC 9218（ Scalable priority ） Together for Web Open an important new chapter .

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