Shi Yang

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CAPWAP Protocol and Dot11 Binding MIB

• Shi Yang
• David T. Perkins
• IETF 70th 3 Dec 2007, Vancouver

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Agenda

• Problem Domain
• Design Objectives
• Basic Idea
• CAPWAP-MIB
• CAPWAP-DOT11-MIB
• An Example of MIB Usage
• Current MIB Work Status
• Next Step

General information for MIB design
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Problem Domain

• The IEEE standards have well-defined MIB for
  wireless binding technologies such as 802.11,
  802.16.
• Current centralized wireless architectures of
  most vendors do not reuse IEEE MIB standards,
  while they define some private MIBs.
• It will make interoperability impossible IEEE
  and IETF WLAN MIBs will be unable to work well
  together
• .

We require a way to avoid reinventing the
wheel for Centralized Wireless Architecture.
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Design Objectives for MIB

• To work well under centralized architectures,
  and provide a way to centrally manage and control
• wireless network by SNMP
• To be consistent with CAPWAP protocol
• To reuse current MIB standards and future
  extensions for a wireless binding technology
• To enable interoperability between vendors
• To meet operator requirements for centralized
  architectures

Reuse
802.11
802.11a/b/g
802.11e
802.11i
802.11k
IEEE WG MIB standards
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Basic Idea (1/3)

• The SNMP agent run on the AC side, and it MAY
  not be required on the WTP side
• MIB files defined separately
• 1) CAPWAP protocols (CAPWAP-MIB)
• 2)Wireless binding (CAPWAP-Dot11 MIB)
• The CAPWAP-MIB is independent of any wireless
  binding technologies

The MIB design follows same idea as CAPWAP
Centralized Control
CAPWAP
WTP
AC
Operator
SNMP
WTP
SNMP Agent
WTP
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Basic Idea (2/3)

• To decide on the configured and monitored MIB
  objects is NOT
• very difficult, as CAPWAP protocol already
  defines them well

• To be independent of any wireless binding
  technologies and
• Have ability to reuse MIB standards of other
  SDOs, is the Main
• Challenge for design of the CAPWAP MIB
• The ifIndex (RFC1213) will play a role in
  bridging between
• MIB standards defined by different SDOs

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Basic Idea (3/3)

• The operator could manage and control the
  centralized wireless
• architectures using multiple MIB standards
  defined by
• multiple SDOs, while keeping them loosely coupled.

Operator
SNMP
Agent
IETF Organization
IEEE 802.11 WG
Other Wireless Binding
CAPWAP-DOT11-MIB
IEEE MIB
IEEE 802.16
RFID
CAPWAP-MIB
IF-MIB
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CAPWAP-MIB

• MIB function
• Background Information
• Basic Idea
• WTP Virtual Radio Interface

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Function
CAPWAP-MIB function - From AC to centrally
managed and monitored WTPs - As a generic
mechanism, the MIB module is independent of any
specific wireless binding technologies - The
MIB module supports CAPWAP protocol parameters
queries - The MIB module supports showing the
WTPs current state - The MIB module supports
indicating the WTP Virtual Radio Interface and
PHY radios mapping relationship - Counters are
provided for WTP, radio's reboot event,
hardware failure etc. - The MIB module provides
the various notification like channel-up, join
failure, etc.
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Background Information (1/2)

• As centralized Wireless architecture, the
  operator has to
• prepare configuration at AC side before WTPs
  connects to AC.
• For any wireless binding technology, the
  configuration
• and management of radio is very important.
• Under centralized Wireless architecture

WTP Id
Identified by
PHY Radio

Radio Id
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Background Information (2/2)

• As usual, the standard of a binding technology
  provides MIB
• standard for radio management on its own.

• For example, according to IEEE 802.11 WG MIB
  standards,
• the MIB tables such as Dot11OperationTable are
  able to
• support WTP radio configuration.
• These tables use ifIndex as the index, and work
  well under
• standalone Wireless architecture

IEEE 802.11 WG MIB
Identified by
PHY Radio
ifIndex
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Basic Idea

• To reuse MIB objects (defined by SDOs such as
  IEEE) for
• radio is very import
• To reuse IEEE 802.11 WG and other WGs MIB
  standards,
• the key point is to reuse the idea of ifIndex

• To have a way to maintain the mapping
  relationship between
• WTP id radio id and ifIndex

PHY Radio
CAPWAP
IEEE 802.11 WG MIB
Identified by
Identified by
WTP Id
ifIndex

How to map to each other?
Radio Id
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WTP Virtual Radio Interface (1/2)

• IfIndex can identify an interface in abstract
  way, and it does NOT
• care for an interfaces PHY location (WTP or AC)

• AC can have interfaces of WTP Virtual Radio
  Interface ifType,
• it will logically represents PHY radios on the
  WTPs side
• It looks like that PHY radios are located on the
  AC side
• Operator can operate radios by MIB tables (such
  as IEEE
• 802.11 WGs) with ifIndex of WTP Virtual Radio
  Interface
• as Index

AC
WTP
WTP Virtual Radio Interface 1
Operator
PHY Radio 1
SNMP
CAPWAP
WTP Virtual Radio Interface 2
PHY Radio 2
WTP Virtual Radio Interface n
PHY Radio n
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WTP Virtual Radio Interface (2/2)

• As an Abstract interface, "WTP Virtual Radio
  Interface" could be used by any wireless binding
  technology such as IEEE 802.11 and 802.16
• The table of capwapRadioBindTable will indicate
  the mapping
• relationship between WTP id Radio id and
  IfIndex

PHY Radio
IEEE 802.11 WG MIB (or any wireless binding)
CAPWAP
WTP Id
ifIndex
INDEX capwapWTPId, capwapRadioId

Radio Id
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CAPWAP-DOT11-MIB

• MIB function
• Background Information
• WTP Virtual Radio Interface
• Virtual AP

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Function

• CAPWAP-DOT11-MIB Function
• The MIB module supports the reuse of current
  IEEE 802.11 WG MIB standards and future
  extensions
• The MIB module supports the configuration of the
  MAC mode and tunnel mode for Wireless service
• The MIB module supports virtual AP

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Background Information (1/2)

• As centralized Wireless architecture, the
  operator has to prepare configurations for each
  wireless at AC side before WTPs are
• able to connect to AC
• Under centralized Wireless architectures

Identified by
Wireless Service
Wireless Id
Operator could configure MAC type or tunnel mode
for a Wireless service
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Background Information (2/2)

• IEEE 802.11 WG MIB does not suggest how to
  support virtual AP

• According to IEEE 802.11 MIB standards, the MIB
  tables such as
• Dot11AuthenticationAlgorithmsTable are able to
  support
• Wireless configuration (such as authentication
  algorithm),
• and these tables use ifIndex as index

IEEE 802.11 WG MIB
Identified by
Wireless Service
ifIndex
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Wireless Service Interface

• A Wireless service could be abstracted as an
  Interface, and
• which could be identified by ifIndex.

• On the AC side, the MIB table CapwapDot11Wireless
  ConfigTable
• will indicate the mapping relation between A
  Wireless ID and
• ifIndex of a Wireless Service Interface

Wireless ID 2
Wireless ID
Wireless ID 3
Wireless Service Interface
With ifIndex of it to reuse IEEE MIBs
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Virtual AP

• By the table of capwapDot11WirelessBindTable,
  the operator are able to bind Wireless service to
  a specific radio through SNMP
• Wireless system will dynamically create the
  "Wireless BSS Interface
• BSS interface will be used for the data
  forwarding function

Wireless ID
bind
Radio
Dynamically Create
Wireless BSS Interface
Identified by ifIndex
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Summary

• CAPWAP-MIB focus in how to manage and control
  WTP, and how to support any wireless binding
  through the mechanism of WTP Virtual Radio
  Interface
• CAPWAP-DOT11-MIB focus in how to support
  configuration of MAC type and tunnel mode for
  WLAN service, and how to support Virtual AP. With
  WLAN Service Interface, it is able to
• Reuse IEEE 802.11 MIB.
• Wireless binding related MIB objects will be
  defined
• by IEEE such kinds SDOs
• IF-MIB could be used to model interface (such
  as WLAN Service interface)

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An example of MIB Usage (1/4)
1) The mapping relationship between WTP
Virtual Radio Interface and WTP Id Radio id
(CAPWAP-MIB) When configuration for a WTP is
prepared before it connects to AC, the following
information is available in the
CapwapRadioBindTable
Identify a WTP
In CapwapRadioBindTable capwapWTPId
12345678
capwapRadioId
1 capwapWTPVirtualRadioifIndex 10
capwapWirelessBinding
dot11(2)
Identify a radio
ifIndex of a WTP Virtual Radio Interface
The type of Wireless Binding
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An example of MIB Usage (1/5)
2) Operator configure Wireless radio through
IEEE MIB
In Dot11OperationTable (Example)
ifIndex 10,
dot11RTSThreshold 2347,
dot11ShortRetryLimit 7,
dot11LongRetryLimit 4,
dot11FragmentationThreshold 256,
dot11MaxTransmitMSDULifetime 512 .

ifIndex of a WTP Virtual Radio Interface
Wireless Radio Parameter
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An example of MIB Usage (2/5)
3) Configure wireless service
A) Create a "Wireless Service Interface" through
CAPWAP-DOT11-MIB.
In CapwapDot11WirelessConfigTable
capwapDot11WirelessId 1,
capwapDot11WirelessServiceIfIndex 20,
capwapWTPMACType splitMAC(2),
capwapWTPTunnelMode
dot3Tunnel, capwapDot11WirelessConfigRowStatus
create
Wireless ID
ifIndex of Wireless Service Interface
MAC Type and Tunnel Mode
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An example of MIB Usage (3/5)
B) Configure Wireless parameters of "Wireless
Service Interface" through IEEE 802.11 MIB.
In Dot11AuthenticationAlgorithmsTable
(Example) ifIndex
20, dot11AuthenticationAlgorithmsIn
dex 1, dot11AuthenticationAlgorithm
Shared Key, dot11AuthenticationAlg
orithmsEnable true
ifIndex of Wireless Service Interface
Wireless Authentication Parameter
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An example of MIB Usage (4/5)
4) Bind Wireless service to WTP radio
In CapwapDot11WirelessBindTable
ifIndex 10,
capwapDot11WirelessId 1,
capwapDot11WirelessBSSIfIndex 30,
capwapDot11WirelessBSSRowStatus create
ifIndex of WTP Virtual Radio Interface
Wireless Id
ifIndex of Wireless BSS Interface
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An example of MIB Usage (5/5)
5) Operator query the statistic data
Operator could query statistic data of WTP,
radio, station objects by IF-MIB, IEEE 802.11 MIB
(such as dot11CountersTable), CAPWAP-MIB and
CAPWAP-DOT11-MIB (such as capwapWTPRebootStatsTabl
e)
Counters refer to CAPWAP Protocol
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Current MIB Work Status

• The first version(00) of CAPWAP-MIB and
• CAPWAP-DOT11-MIB were published in July 2007.
• http//tools.ietf.org/id/draft-yangshi-capwap-802
  dot11-mib-00.txt
• http//tools.ietf.org/id/draft-yangshi-capwap-bas
  e-mib-00.txt
• The latest MIB drafts (version 01) are planed to
  be published
• after IETF-70th Meeting.
• The co-editor of drafts are Shi Yang and David T.
  Perkins
• Request More Comments from CAPWAP WG

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Next Step

• Request CAPWAP-MIB and CAPWAP-DOT11-MIB
• to be CAPWAP WGs Formal Drafts.

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• Questions?
• Comments?