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Leaky-Bucket Algorithm for High Speed Network Access Control

IP.com Disclosure Number: IPCOM000105172D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Cherbonnier, J: AUTHOR [+7]

Abstract

A leaky bucket, or usage parameter controller, is a device located at the access port of a fast packet switching network, which is responsible for controlling users data flows in order to protect the network from excessive traffic. Typically, it is made of the following parts:

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Leaky-Bucket Algorithm for High Speed Network Access Control

      A leaky bucket, or usage parameter controller, is a device
located at the access port of a fast packet switching network, which
is responsible for controlling users data flows in order to protect
the network from excessive traffic.  Typically, it is made of the
following parts:

o   The spacer enforces the connection peak rate (rate beta);

o   The Green Token Pool controls the number of packets that can be
    admitted as green;

o   The Red Token Pool controls the number of packets that can be
    admitted as red.  In case of congestion in the network, red
    packets are discarded first.  Red packets are marked with the CLP
    bit set in the case of ATM, with the DE bit set in the case of
    Frame Relay.

      In a typical implementation, packets need a number of tokens
avail able in order to be admitted.  The number is function of the
packet size.  If no green token is available, the packet can either
wait in the packet buffer, or leave immediately as a red packet
(depending on whether the packet is pre-marked green or not).  Once
the green token pool is ex hausted, green tokens cannot be used until
the green pool has reached the level Roff again.  The green token
pool is refilled on a permanent basis, while the red one is refilled
only when it is red and when a red token is needed.

      The implementation of the leaky bucket can be simplified by
speci fying the operation of the spacer and of the green bucket as
following.

      The spacer uses a variable quantizer step for computing the
number of tokens.  This allows computation by table lookup, while
avoiding to penalize traffic...