Introduction Flashcards
a congestion control protocol for TCP (transmission control protocol) and the current default TCP algorithm in Linux.
CUBIC
This protocol modifies the linear window growth function of existing TCP standards to be a cubic function in order to improve the scalability of TCP over
fast and long distance networks.
CUBIC
achieves more equitable bandwidth allocations among flows with different RTTs (round trip times) by making the window growth to be independent of RTT – thus those flows grow their congestion window at the same rate.
CUBIC
During steady state, this will increase the window size aggressively when the window is far from the saturation point, and the slowly when it is close
to the saturation point.
CUBIC
The total number of packets needed in flight while keeping the bandwidth fully utilized, in other words, the size of the congestion window.
bandwidth and delay product (BDP)
grows its window one per
round trip time (RTT)
In standard TCP like TCP-Reno, TCP-NewReno and TCP-SACK, TCP grows its window one per
round trip time (RTT)
TCP grows its window one per
round trip time (RTT). This
This makes the data transport speed
of TCP used in all major operating systems includingWin-
dows and Linux rather sluggish, to say the least, extremely
under-utilizing the networks especially if the length of flows
is much shorter than the time TCP grows its windows to
the full size of the BDP of a path.
the Linux community selected this protocol as the default TCP algorithm in order to handle the under-utilization problem of TCP,
BIC-TCP
This feature adds to the stability of the protocol because even if the protocol makes mistakes in finding the max win-ow, it finds the next max window near the previous max point first, thus staying at the previous saturation point longer.
BIC-TCP increases the window exponentially.
Note that an exponential function (a convex function) grows very slowly at the beginning (slower than a linear function).
The next version of BIC-TCP. It greatly simplifies the window adjustment algorithm of BIC-TCP by replacing the concave and convex window growth portions of BIC-TCP by a cubic function (which contains both concave and convex portions).
CUBIC
One of the real-time
a congestion epoch
Its window growth depends only on the real time
between two consecutive congestion events.
The key feature of CUBIC
One congestion
event is the time when TCP undergoes fast recovery.
this real time is called a congestion epoch
