Configuration and Provisioning for Wireless Access Points (CAPWAP) Problem Statement
RFC - Informational
(February 2005; No errata)
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RFC 3990 (Informational)
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Network Working Group B. O'Hara
Request for Comments: 3990 P. Calhoun
Category: Informational Airespace
Docomo Labs USA
Configuration and Provisioning for Wireless Access Points (CAPWAP)
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 (C) The Internet Society (2005).
This document describes the Configuration and Provisioning for
Wireless Access Points (CAPWAP) problem statement.
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
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