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This MIB is intended to be implemented on all 802.11
Access Points and Wireless Bridges that need to
participate in the context management process and
make use of the services provided by the entities
offering WDS and WNS. The term '802.11 station'
refers to one of the Access Point / Wireless Bridge
throughout the MIB unless stated otherwise.
The hierarchy of the devices offering the wireless
domain and network services looks like the following.
+= = = = +
| |
| WNS | (Campus level)
| |
+= = = = +
/ \n/ \n/ \n/ \n/ /
+= = =+ += = =+
| | | |
| WNS | | WNS |
| | | |
+= = =+ += = =+
/ \n/ \n/ \n/ \n/ / /
+=====+ +=====+ +=====+
| | | | | |
| WDS | | WDS | | WDS | ( Subnet
| | | | | | level-
+=====+ +=====+ +=====+ Single
/ broadcast
/ domain )
/ \n/ \n/ \n/ / / /
+~-~-~+ +~-~-~+ +~-~-~+ +~-~-~+
+ + + + + + + +
+ AP + + AP + + AP + + AP +
+ + + + + + + +
+~-~-~+ +~-~-~+ +~-~-~+ +~-~-~+
.. . . .
. . . . .
. . . . .
. . . . .
. . . . .
/ / / / /
+.....+ +.....+ +-.-.-.+ +~-~-~+ +......+
+ + + + + + + + + +
+ MN + + MN + + WGB + + AP + + MN +
+ + + + + + + + + +
+.....+ +.....+ +-.-.-.+ +~-~-~+ +......+
. . .
. . .
. . .
. . .
/ / /
++++++++ +......+ +......+
+ + + + + +
+ EN + + MN + + MN +
+ + + + + +
++++++++ +......+ +......+
The diagram above depicts the overall campus network
hierarchy and the services being offered at various
levels in the hierarchy. Here, authentication
services for infrastructure nodes are offered by the
root node, the node providing WNS at the topmost
(Campus) level. This node spans an enterprise campus
that resides in a geographic location. In this case,
an 802.11 station performs initial authentication
with the topmost WNS entity. It also gets the keys
needed for secure context transfer by communication
with that entity.
WNS are offered at various levels as shown in the
hierarchy to achieve scalability. WNS at the
subsequent levels other than the root level include
authentication services for MNs and are typically
confined to a single building.
At the broadcast domain level, the WDS includes
authentication and registration services for the APs.
An AP provides proxy authentication and registration
services for the MNs. The APs that connect to parent
APs through the wireless interface ( as shown by the
dotted lines ) are Repeater-APs. The WGBs are managed
in the same manner as the MNs. However, the Ethernet
Nodes ( EN ) that are connected to the WGB won't be
served as part of the WDS.
GLOSSARY
Access Point ( AP )
Any entity that contains an 802.11 medium access
control ( MAC ) and physical layer ( PHY ) interface
and provides access to the distribution services via
the wireless medium for associated clients.
Wireless Bridge
An 802.11 entity that provides wireless connectivity
between two wired LAN segments and is used in point-
to-point or point-to-multipoint configurations.
Mobile Node ( MN )
A roaming 802.11 wireless device in a wireless
network associated with an access point.
WorkGroup Bridge ( WGB )
A work-group bridge is a non-STP AP with an 802.11
primary port and a secondary Ethernet port that
provides access to a non-STP secondary Ethernet LAN
segment. STP refers to the IEEE 802.1D Spanning Tree
Protocol. An 'STP AP' executes the 802.1D STP and
the 802.1D STP is operated on an 'STP link'. A
'non-STP AP' does not execute the 802.1D STP.
Repeater-AP
A repeater is a 'wireless AP' that is attached to a
parent AP on an 802.11 primary port. The Ethernet
port is disabled in a Repeater-AP.
Infrastructure Node ( IN )
This term refers to Access Points, Wireless Bridges
and those devices that implement and offer WNS and
WDS as shown in the network hierarchy.
Ethernet Node ( EN )
The node that gets the uplink to the Wireless AP
via the WGB. This node connects to the WGB through
its primary Ethernet port.
Context
The mobility context for an MN includes its current
mobility bindings with the APs, IP/802 address
bindings, cached configuration parameters, QoS state,
IP group membership, authentication state, accounting
statistics, and other dynamically derived protocol
state information.
Wireless Domain Services
The set of services being offered at a particular
broadcast domain that may be an IP subnet or a
particular VLAN. The services include the following.
1. MN security credential caching to provide seamless,
secure intra-subnet roaming.
2. Authenticated context transfer for roaming client
within the subnet.
Since, by definition, the WDS are bound to one subnet
( broadcast domain ), if implemented in a device
spanning multiple subnets, the implementation should
take care to provide separate set of services for
each of the subnets.
Wireless Network Services
The set of services that can be visualized as being
offered at various levels other than the lowest
(subnet) level of a hierarchical campus network.
At the topmost level, infrastructure authentication
services for all the devices in the network that
provide WNS and WDS are offered. In case if WNS are
not distributed at several levels as shown in the
hierarchy above and is confined to be offered only at
a single topmost level, the services offered also
include authentication services for the MNs.
WNS Entity
The logical entity that resides in an infrastructure
node and offers WNS to the descendants of that
infrastructure node in the wireless services
hierarchy.
WDS Entity
The logical entity that resides in an infrastructure
node and offers WDS to the descendants of that
infrastructure node in the wireless services
hierarchy.
WS Entity
Refers to one of WNS / WDS Entities.
Parent Node
The entity that immediately precedes an infrastructure
node in the hierarchy. For mobile nodes, the parent
APs provide proxy wireless services by talking to their
immediate parent entities providing WDS.
Root Node
The entity that is at the highest level in the network
hierarchy. The root node acts as the IN Authenticator
for the infrastructure nodes. In case if WNS are not
distributed, the root node also acts as the Mobile Node
Authenticator ( See description below ).
Descendant
A node that is in the sub-tree of the campus hierarchy
tree rooted at the node providing WNS at the campus
level.
Infrastructure Node ( IN ) Authenticator
The logical entity that communicates with the AAA
server and provides authentication services for the
infrastructure nodes. Details of the IN Authenticator
has to be configured in the device providing WDS
manually. The AP learns about the IN Authenticator
automatically upon registering with its immediate
parent. The WDS also includes MN authentication
services if the entity providing WDS is at the
topmost level in the hierarchy.
Mobile Node ( MN ) Authenticator
The logical entity that communicates with the AAA
server and provides authentication services for mobile
nodes. An infrastructure node learns the whereabouts
of the MN Authenticator from the root node.
Wireless Network Manager ( WNM )
The network management system that manages the
entire hierarchy of devices providing WNS and WDS.
Advertisement
The process by which the Access Points identify their
parent entities providing WDS. APs listen to the
advertisements of the WDS entities and gets registered
with one of those entities to facilitate secured
context transfer.
WLCCP
Wireless LAN Context Control Protocol. Used to
establish and manage the network topology and
securely manage the 'operational context' for mobile
stations in a campus network.
AAA
Authentication, Authorization, Accounting
The method by which users are authenticated,
authorized and tracked to gain access and move about
inside a network. A node will request network access
through an appropriate protocol to an authentication
server that provides protocols and services for
providing authentication, authorization and session
accounting.
Service Set Identifier ( SSID )
802.11 Service Set Identifier. An SSID identifies a
set of mobile nodes grouped into a logical 'service
set' and the APs that provide access for the service
set.
Wireless services at subnet level
=================================
+========+
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| WDS | ( Subnet level - Broadcast
| | domain )
+========+
/ \n/ \n/ \n/ \n/ \n/ /
+~-~-~+ +~-~-~+
+ + + +
+ AP + + AP +
+ + + +
+~-~-~+ +~-~-~+
. . .
. . .
. . .
. . .
. . .
. . .
/ / /
+......+ +-.-.-.+ +~-~-~-+
+ + + + + +
+ MN + + WGB + + AP +
+ + + + + +
+......+ +-.-.-.+ +~-~-~-+
The above diagram depicts how wireless services are
being offered in a network rooted at the device
implementing WDS. In such a network, the WDS entity
provides authentication services to both the
infrastructure and mobile nodes.
An 802.11 station in this hierarchy mentioned above
performs the following.
1) Provides proxy authentication and registration
services to the MNs, WGBs and repeater-APs. The
station forwards all the authentication and
registration requests of its clients to its parent
node offering WDS and acting as the IN Authenticator
to enable the authentication and registration of its
clients.
2) Participates in the election process to elect
the node that will provide WDS for a particular
broadcast domain.
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