Article development led by queue.acm.org

Networks without effective AQM may again
be vulnerable to congestion collapse.
By JiM Gettys anD KathLeen niChoLs
Bufferbloat:
Dark Buffers
in the internet

TodaY’s ne TwoRKs aRe suffering from unnecessary latency and poor system performance. The culprit is bufferbloat, the existence of excessively large and frequently full buffers inside the network. Large buffers have been inserted all over the Internet without sufficient thought or testing. They damage or

 

defeat the fundamental congestion-avoidance algorithms of the Internet’s most common transport protocol. Long delays from bufferbloat are frequently misattributed to insufficient bandwidth and this misinterpretation of the problem leads to the wrong solutions being proposed.

Congestion is an old problem on the
Internet, appearing in various forms
with different symptoms and causing
major problems. Buffers are essential
to the proper functioning of packet
networks, but overly large, unman-
aged, and uncoordinated buffers cre-
ate excessive delays that frustrate and
baffle end users. Many of the issues
that create delay are not new, but their
collective impact has not been widely
understood. Thus, buffering problems
have been accumulating for more than
a decade. We strive to present these
problems with their impacts so the
community can understand and act
upon the problem and, we hope, learn
to prevent future problems.

 

internet Buffers and Congestion The latency a packet experiences in a network is made up of transmission delay (the time it takes to send it across communications links), processing delay (the time each network element spends handling the packet), and queuing delay (the time spent waiting to be processed or transmitted). Paths between communicating endpoints in the Internet are typically made up of many hops with links of different rates or bandwidths; the smallest