RFC 3132 (rfc3132) - Page 2 of 14

Dormant Mode Host Alerting ("IP Paging") Problem Statement

RFC 3132      Dormant Mode Host Alerting Problem Statement     June 2001


   When a mobile is in low power consumption mode, special steps need to
   be taken to locate the mobile and alert it.  These steps differ
   depending on the radio link, but the generic name for this process is
   paging, a term that is commonly used in cellular telephony.

   In this document, after some initial definitions and material related
   to more clearly explaining what paging is, we assess the need for
   paging in existing IP mobility protocols (namely Mobile IP [1] [2]).
   We then develop a list of work items for the Seamoby working group
   related to this need.  Note that the discussion in this document and
   the conclusions regarding work items are directed toward existing IP
   mobility protocols and existing radio link protocols.  Should a major
   change occur in radio link support or the available IP mobility
   protocols, such as the introduction of a micromobility protocol for
   IP, the issues examined in this document may need to be revisited.

2.0 Definitions

   The following definitions are relevant with respect to clarifying the
   paging functionality:

      Dormant Mode - A state in which the mobile restricts its ability
      to receive normal IP traffic by reducing monitoring of radio
      channels.  This allows the mobile to save power and reduces
      signaling load on the network.

      Time-slotted Dormant Mode - A dormant mode implementation in which
      the mobile alternates between periods of not listening for any
      radio traffic and listening for traffic.  Time-slotted dormant
      mode implementations are typically synchronized with the network
      so the network can deliver traffic to the mobile during listening
      periods.  Additionally, the mobile may be restricted to listening
      on specific signaling channels that, according to current
      practice, are not typically used to carry IP traffic.

      Paging - As a consequence of a mobile-bound packet destined for a
      mobile currently in dormant mode, signaling by the network through
      radio access points directed to locating the mobile and alerting
      it to establish a last hop connection.  This messaging is in
      addition to simply delivering the packet to the mobile, i.e., last
      hop routing of packets is NOT considered to be paging.

      Paging Area - Collection of radio access points that are signaled
      to locate a dormant mode mobile node.  A paging area does not
      necessarily correspond to an IP subnet.  A dormant mode mobile
      node may be required to signal to the network when it crosses a
      paging area boundary, in order that the network can maintain a
      rough idea of where the mobile is located.



Kempf                        Informational