The QUIC protocol was developed by Google to improve performance over TCP for web applications by reducing latency. QUIC sits on top of UDP rather than TCP, allowing it to establish an encrypted connection in one round trip rather than the multiple round trips required by TCP. This reduces latency compared to HTTPS which uses TCP. QUIC also allows for multiplexed streams that can continue independently if one stream experiences packet loss, avoiding the head-of-line blocking that can occur with TCP connections. Major uses of QUIC include web browsing, video streaming, cloud services, and gaming.

1. INFRASTRUCTURE PROTOCOLS
By Shivam Pandey
PGDBT202206
Quick UDP Internet Connections Protocol

2. AGENDA
➢ QUIC protocol
➢ Comparison between the TCP stack and QUIC
➢ What’s QUIC used for?

3. What is the QUIC protocol?
❖ Quick UDP Internet Connections (QUIC) was developed (and still undergoing developments) to work as a
low-latency and independent TCP connection.
❖ Google originally developed the Quick UDP Internet Connections protocol as an experiment to improve the
performance of Google’s web applications.
❖ The connection latency in QUIC is reduced by reducing the number of round trips incurred during
connection establishment in TCP, such as those for handshaking, data requests, and encryption exchanges.
❖ In contrast to HTTPS leveraging TLS, which is built on top of the TCP protocol, QUIC is built on top of
UDP.
❖ TCP, being connection oriented, must perform a three-way handshake to initiate any connection. After this,
encryption parameters must be negotiated for TLS.
❖ Only then does the data the user was looking for actually start flowing. This means that it takes multiple
round trips just to establish a path for two devices to communicate.

4. What is the QUIC protocol CONTD.
❖ This results in latency for the user. In a world where every piece of information is a click away, speed is everything, so
reducing latency is critical.
❖ Since QUIC uses UDP, there is no need to complete a complex handshake to establish the first connection. The
protocol includes initiating encryption, and the exchange of keys, into the initial handshake process. It takes only one
round trip to establish a path for communication.
Comparison between the TCP stack and QUIC

5. ➢ As we can see, QUIC sits on top of UDP while encryption is part of the protocol. Since UDP is
a connectionless protocol, QUIC handless all of the logic to guarantee a reliable connection
between a client and a server.
➢ Supports zero round-trip time (0RTT)
➢ Flow control loss
➢ Recovery
Some uses-
❖ Web Browsing
❖ Video Streaming
❖ Cloud Services
❖ Gaming

6. The main performance improvement of QUIC over TCP come from two key differentiators:
Connection handshake: TCP required a 3-way handshake to establish a connection, and, on top of that,
you also need to negotiate the TLS connection. QUIC is built on top of UDP so it requires 1 packet to establish
the connection, including TLS.
Multiplexing: the communication between the client and the server is multiplexed and this overcomes the
head-of-line blocking issues that are common with TCP connections.
Connection migration:Very valuable feature: moving from WiFi to LTE without renegotiating
the session!
Congestion control: As we said we have multiplexing so there will be a congestion control.

7. What’s QUIC used for CONTD.
❖ There’s also a benefit of multiplexing. While HTTP/2 protocol does allow multiple HTTP streams to
share a single TCP connection, there is still a problem with packet loss. Since TCP is a connection-
oriented protocol and needs to recover the lost data, any packet loss on any of the multiplexed streams
would lead to all streams on that connection becoming blocked until that loss is recovered.

8. ❖ QUIC resolves this issue by enabling each lane to keep running independently. UDP is indifferent to
the lost packets. The protocol has defined the retransmission parameters, and enables the
retransmission of data in just one stream, as opposed to blocking all streams.
❖ So there’s no slowing down in other lanes.
References-
❖ https://www.auvik.com/franklyit/blog/what-is-quic-protocol/
❖ https://ietresearch.onlinelibrary.wiley.com/doi/full/10.1049/cmu2.12154#:~:text=A%20QUIC%20has%
20default%20pluggable,introduced%20%5B12%2C%2013%5D.
❖ https://www.google.com/search?q=0-rtt+full+form&rlz=1C1JJTC_enIN1035IN1035&oq=0-
rtt+full+form&aqs=chrome..69i57j33i160.12318j0j7&sourceid=chrome&ie=UTF-8