Browse Prior Art Database

Accounting Mechanism for Connections with Small Bandwidth Reservation Requirements

IP.com Disclosure Number: IPCOM000105974D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Chang, RF: AUTHOR [+6]

Abstract

In a communications network that supports connections with bandwidth reservation, it is necessary for the nodes in that network to maintain information about existing connections. This is necessary to allow the nodes to decide whether they can accept additional connections. Described is a method that reduces the amount of information that needs to be maintained. It is an enhancement to the method described in "Distributed Control for Paris", Proceedings of 9th ACM Symposium on Principals of Distributed Computing [*].

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This is the abbreviated version, containing approximately 52% of the total text.

Accounting Mechanism for Connections with Small Bandwidth Reservation Requirements

      In a communications network that supports connections with
bandwidth reservation, it is necessary for the nodes in that network
to maintain information about existing connections.  This is
necessary to allow the nodes to decide whether they can accept
additional connections.  Described is a method that reduces the
amount of information that needs to be maintained.  It is an
enhancement to the method described in "Distributed Control for
Paris", Proceedings of 9th ACM Symposium on Principals of Distributed
Computing [*].

      A connection request contains a specified bandwidth and a path,
consisting of  a set of links  through the network.  Each  node along
the path  receives  a copy  of  the  connection  request and
identifies  its outgoing link.   It adds the  bandwidth specified  in
the request  to the bandwidth already  reserved on that link  and
compares this to  the total bandwidth  available  on that  link.   If
it  is  less, the  request  is accepted.  Otherwise, it is rejected.

      In order to  provide a measure of fault tolerance,  each node
maintains a table for each of its links.   This table contains an
identifier for each connection  using that  link and  the amount  of
bandwidth  used by  that connection.

      Each node  that initiates a  connection request will
periodically  send a refresh for that  connection to the nodes along
the  connection's path to indicate that it wishes to continue
reserving the connection's bandwidth.  Each node along the path that
fails to receive some consecutive number of these  refreshes for  a
given  connection will  assume that  the reserved bandwidth is no
longer needed and will free it.

      The  drawback  to  this  approach  is  that  explicit
awareness  of  all connections requires  significant amounts of
memory  that impacts product cost and  performance.  For  example, a
SONET OC24  link of  1.2GBPS can support over 20,000 64KBPS voice
connections.  This requires a table that can contain 20,000 entries.

      To solve these problems, this disclosure proposes a fixed size
connection table that is managed  as a cache.  As lo...