Google's researchers claims that they will speed up the Internet by improving the transport layer of the Transmission Control Protocol (TCP) protocol.
Transmission Control Protocol (TCP), the workhorse of
the Internet, is designed to deliver all the Web's
content and operate over a huge range of network
types. To deliver content effectively, Web browsers
typically open several dozen parallel TCP connections
ahead of making actual requests. This strategy
overcomes inherent TCP limitations but results in high
latency in many situations and is not scalable.
Google's recommendations to make TCP faster include:
- Increase TCP initial congestion window to 10 (IW10).
The amount of data sent at the beginning of a TCP
connection is currently 3 packets, implying 3 round
trips (RTT) to deliver a tiny 15KB-sized content.
indicate that IW10
reduces the network latency of Web transfers by over
- Reduce the initial timeout from 3 seconds
to 1 second
. An RTT of 3 seconds was appropriate a
couple of decades ago, but today's Internet requires a
much smaller timeout.
- Use TCP Fast Open (TFO). For 33% of all HTTP
requests, the browser needs to first spend one RTT to
establish a TCP connection with the remote peer. Most
HTTP responses fit in the initial TCP congestion
window of 10 packets, doubling response time. TFO
removes this overhead by including the HTTP request in
the initial TCP SYN packet. Google has demonstrated
TFO reducing Page Load time by 10% on average, and
over 40% in many situations. Google's research paper
concerns such as dropped packets and DOS attacks when
- Use Proportional Rate Reduction for TCP (PRR).
Packet losses indicate the network is in disorder or
is congested. PRR, a new loss recovery algorithm,
retransmits smoothly to recover losses during network
congestion. The algorithm is faster than the current
mechanism by adjusting the transmission rate according
to the degree of losses. PRR is now part of the Linux
kernel and is in the process of becoming part of the
In addition, Google is developing algorithms to
recover faster on noisy mobile networks, as well as a
guaranteed 2-RTT delivery during startup. The
company's work on TCP is open-source and publicly
available through the Linux kernel, IETF standards
proposals, and research publications.