Cisco Cisco 2000 Series Wireless LAN Controller White Paper
LWAPP Traffic Study
Document ID: 99947
Contents
Introduction
Setup
LWAPP Control Channel
Initial/One−time Exchanges
Ongoing Exchanges
LWAPP Data
Frame Padding
Fragmentation
Conclusion
Related Information
Setup
LWAPP Control Channel
Initial/One−time Exchanges
Ongoing Exchanges
LWAPP Data
Frame Padding
Fragmentation
Conclusion
Related Information
Introduction
The IETF−RFC draft, submitted to the Control And Provisioning of Wireless Access Points (CAPWAP)
working group, describes the Light Weight Access Point Protocol (LWAPP) as a protocol developed with the
goal to define communication guidelines between Wireless Termination Points (Access Points) and Access
Controllers (Wireless LAN Controllers). All LWAPP communications can be classified into one of these two
message types:
working group, describes the Light Weight Access Point Protocol (LWAPP) as a protocol developed with the
goal to define communication guidelines between Wireless Termination Points (Access Points) and Access
Controllers (Wireless LAN Controllers). All LWAPP communications can be classified into one of these two
message types:
LWAPP Control Channel
•
LWAPP Encapsulated Data
•
LWAPP can function in either Layer 2 or Layer 3 transport mode. Layer 2 LWAPP communications are
encapsulated in Ethernet frames and can be identified with an EtherType value of 0x88BB. Due to its
reliability on Ethernet, Layer 2 LWAPP mode of operation is not routable and requires Layer 2 visibility
between the WLCs and APs. Layer 2 is considered deprecated and protocol statistics outlined in this traffic
study are based on Layer 3 LWAPP transport mode. Layer 3 LWAPP transport mode specifies the exchange
of LWAPP messages on the IP network in the form of UDP−encapsulated packets. The LWAPP tunnel is
maintained with the IP Address of the WLC (ap−manager) interface and the IP Address of the AP. This traffic
study reveals the actual amount of overhead that LWAPP messages present on a network and a baseline of
LWAPP operation in a standard install.
encapsulated in Ethernet frames and can be identified with an EtherType value of 0x88BB. Due to its
reliability on Ethernet, Layer 2 LWAPP mode of operation is not routable and requires Layer 2 visibility
between the WLCs and APs. Layer 2 is considered deprecated and protocol statistics outlined in this traffic
study are based on Layer 3 LWAPP transport mode. Layer 3 LWAPP transport mode specifies the exchange
of LWAPP messages on the IP network in the form of UDP−encapsulated packets. The LWAPP tunnel is
maintained with the IP Address of the WLC (ap−manager) interface and the IP Address of the AP. This traffic
study reveals the actual amount of overhead that LWAPP messages present on a network and a baseline of
LWAPP operation in a standard install.
Note: The LWAPP specification is discussed in great detail at LWAPP−IETF Draft.
Setup
This document presents statistics related to the operation of LWAPP only and any functionality that is not
defined by the protocol specification, such as inter−controller roaming, is outside the scope of this document.
Furthermore, the traffic study only covers Layer 3 mode of LWAPP operation.
defined by the protocol specification, such as inter−controller roaming, is outside the scope of this document.
Furthermore, the traffic study only covers Layer 3 mode of LWAPP operation.
Figure 1: LWAPP Traffic Study setup