RFC 2814 (rfc2814) - Page 2 of 60

SBM (Subnet Bandwidth Manager): A Protocol for RSVP-based Admission Control over IEEE 802-style networks

RFC 2814             SBM (Subnet Bandwidth Manager)             May 2000


   reservation setup protocols is needed for specific link-layer
   technologies such as shared and switched IEEE-802-style LAN
   technologies.

   This document defines SBM, a signaling protocol for RSVP-based
   admission control over IEEE 802-style networks.  SBM provides a
   method for mapping an internet-level setup protocol such as RSVP onto
   IEEE 802 style networks.  In particular, it describes the operation
   of RSVP-enabled hosts/routers and link layer devices (switches,
   bridges) to support reservation of LAN resources for RSVP-enabled
   data flows.  A framework for providing Integrated Services over
   shared and switched IEEE-802-style LAN technologies and a definition
   of service mappings have been described in separate documents [RFC-
   FRAME, RFC-MAP].

2. Goals and Assumptions

   The SBM (Subnet Bandwidth Manager) protocol and its use for admission
   control and bandwidth management in IEEE 802 level-2 networks is
   based on the following architectural goals and assumptions:

      I. Even though the current trend is towards increased use of
      switched LAN topologies consisting of newer switches that support
      the priority queuing mechanisms specified by IEEE 802.1p, we
      assume that the LAN technologies will continue to be a mix of
      legacy shared/ switched LAN segments and newer switched segments
      based on IEEE 802.1p specification.  Therefore, we specify a
      signaling protocol for managing bandwidth over both legacy and
      newer LAN topologies and that takes advantage of the additional
      functionality (such as an explicit support for different traffic
      classes or integrated service classes) as it becomes available in
      the new generation of switches, hubs, or bridges.  As a result,
      the SBM protocol would allow for a range of LAN bandwidth
      management solutions that vary from one that exercises purely
      administrative control (over the amount of bandwidth consumed by
      RSVP-enabled traffic flows) to one that requires cooperation (and
      enforcement) from all the end-systems or switches in a IEEE 802
      LAN.

      II. This document specifies only a signaling method and protocol
      for LAN-based admission control over RSVP flows.  We do not define
      here any traffic control mechanisms for the link layer; the
      protocol is designed to use any such mechanisms defined by IEEE
      802.  In addition, we assume that the Layer 3 end-systems (e.g., a
      host or a router) will exercise traffic control by policing
      Integrated Services traffic flows to ensure that each flow stays
      within its traffic specifications stipulated in an earlier
      reservation request submitted for admission control.  This then



Yavatkar, et al.            Standards Track