Configuration and Provisioning for Wireless Access Points (CAPWAP) Problem Statement
RFC 3990

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Network Working Group                                          B. O'Hara
Request for Comments: 3990                                    P. Calhoun
Category: Informational                                        Airespace
                                                                J. Kempf
                                                         Docomo Labs USA
                                                           February 2005

  Configuration and Provisioning for Wireless Access Points (CAPWAP)
                           Problem Statement

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This document describes the Configuration and Provisioning for
   Wireless Access Points (CAPWAP) problem statement.

1.  Introduction

   With the approval of the 802.11 standard by the IEEE in 1997,
   wireless LANs (WLANs) began a slow entry into enterprise networks.
   The limited data rates of the original 802.11 standard, only 1 and 2
   Mbps, limited the widespread adoption of the technology.  802.11
   found wide deployment in vertical applications, such as inventory
   management, point of sale, and transportation management.  Pioneering
   enterprises began to deploy 802.11, mostly for experimentation.

   In 1999, the IEEE approved the 802.11a and 802.11b amendments to the
   base standard, increasing the available data rate to 54 and 11 Mbps,
   respectively, and expanding to a new radio band.  This removed one of
   the significant factors holding back adoption of 802.11 in large
   enterprise networks.  These large deployments were bound by the
   definition and functionality of an 802.11 Access Point (AP), as
   described in the 802.11 standard.  The techniques required extensive
   use of layer 2 bridging and widespread VLANs to ensure the proper
   operation of higher layer protocols.  Deployments of 802.11 WLANs as
   large as several thousand APs have been described.

O'Hara, et al.               Informational                      [Page 1]
RFC 3990                CAPWAP Problem Statement           February 2005

   Large deployments of 802.11 WLANs have introduced several problems
   that require solutions.  The limitations on the scalability of
   bridging should come as no surprise to the networking community, as
   similar limitations arose in the early 1980s for wired network
   bridging during the expansion and interconnection of wired local area
   networks.  This document will describe the problems introduced by the
   large-scale deployment of 802.11 WLANs in enterprise networks.

2.  Problem Statement

   Large WLAN deployments introduce several problems.  First, each AP is
   an IP-addressable device requiring management, monitoring, and
   control.  Deployment of a large WLAN will typically double the number
   of network infrastructure devices that require management.  This
   presents a significant additional burden to the network
   administration resources and is often a hurdle to adoption of
   wireless technologies, particularly because the configuration of each
   access point is nearly identical to the next.  This near-sameness
   often leads to misconfiguration and improper operation of the WLAN.

   Second, distributing and maintaining a consistent configuration
   throughout the entire set of access points in the WLAN is
   problematic.  Access point configuration consists of both long-term
   static information (such as addressing and hardware settings) and
   more dynamic provisioning information (such as individual WLAN
   settings and security parameters).  Large WLAN installations that
   have to update dynamic provisioning information in all the APs in the
   WLAN require a prolonged phase-over time.  As each AP is updated, the
   WLAN will not have a single, consistent configuration.

   Third, dealing effectively with the dynamic nature of the WLAN medium
   itself is difficult.  Due to the shared nature of the wireless medium
   (shared with APs in the same WLAN, with APs in other WLANs, and with
   devices that are not APs at all), parameters controlling the wireless
   medium on each AP must be monitored frequently and modified in a
   coordinated fashion to maximize WLAN performance.  This must be
   coordinated among all the access points, to minimize the interference
   of one access point with its neighbors.  Manually monitoring these
   metrics and determining a new, optimum configuration for the
   parameters related to the wireless medium is a task that takes
   significant time and effort.

   Fourth, securing access to the network and preventing installation of
   unauthorized access points is challenging.  Physical locations for
   access points are often difficult to secure since their location must
   often be outside of a locked network closet or server room.  Theft of