Руководство По Проектированию для Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter
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Enterprise Mobility 4.1 Design Guide
OL-14435-01
Chapter 2 Cisco Unified Wireless Technology and Architecture
Mobility Groups, AP Groups, and RF Groups
Mobility Group Application
Mobility groups are used to help facilitate seamless client roaming between APs that are joined to
different WLCs. The primary purpose of a mobility group is to create a virtual WLAN domain (across
multiple WLCs) in order to provide a comprehensive view of a wireless coverage area. The use of
mobility groups are beneficial only when a deployment comprises of 'overlapping' coverage established
by two or more APs that are connected to different WLCs. A mobility group is of no benefit when two
APs, associated with different controllers, are in different physical locations with no overlapping
(contiguous) coverage between them (for example, Campus and Branch or between two or more
buildings within a campus).
different WLCs. The primary purpose of a mobility group is to create a virtual WLAN domain (across
multiple WLCs) in order to provide a comprehensive view of a wireless coverage area. The use of
mobility groups are beneficial only when a deployment comprises of 'overlapping' coverage established
by two or more APs that are connected to different WLCs. A mobility group is of no benefit when two
APs, associated with different controllers, are in different physical locations with no overlapping
(contiguous) coverage between them (for example, Campus and Branch or between two or more
buildings within a campus).
Mobility Group—Exceptions
The Cisco Unified Wireless solution offers network administrators the ability to define static mobility
tunnel (Auto Anchor) relationships between an ‘anchor’ WLC and other WLCs in the network. This
option, among other things, is used when deploying wireless guest access services.
tunnel (Auto Anchor) relationships between an ‘anchor’ WLC and other WLCs in the network. This
option, among other things, is used when deploying wireless guest access services.
If the auto anchor feature is used, no more than 24 (foreign) WLCs can be mapped to a designated anchor
WLC. Foreign WLCs do not, by virtue of being connected to the auto anchor, establish mobility
relationships between each other. The anchor WLC must have a ‘static mobility group member’ entry
defined for each foreign WLC where a static mobility tunnel is needed. Likewise for each foreign WLC
where a static mobility tunnel is being configured, the anchor WLC must be defined as a ‘static mobility
group member’ in the foreign WLC.
WLC. Foreign WLCs do not, by virtue of being connected to the auto anchor, establish mobility
relationships between each other. The anchor WLC must have a ‘static mobility group member’ entry
defined for each foreign WLC where a static mobility tunnel is needed. Likewise for each foreign WLC
where a static mobility tunnel is being configured, the anchor WLC must be defined as a ‘static mobility
group member’ in the foreign WLC.
A WLC can only be member of one mobility group for the purpose of supporting dynamic
inter-controller client roaming. A WLC that is configured as an ‘auto anchor’, does not have to be in the
same mobility group as the foreign WLCs. It is possible for a WLC to be a member of one mobility group
whilst at the same time, act as an auto anchor for a WLAN originating from foreign WLCs that are
members of other mobility groups.
inter-controller client roaming. A WLC that is configured as an ‘auto anchor’, does not have to be in the
same mobility group as the foreign WLCs. It is possible for a WLC to be a member of one mobility group
whilst at the same time, act as an auto anchor for a WLAN originating from foreign WLCs that are
members of other mobility groups.
For a discussion on mobility anchor configuration, see
AP Groups
In typical deployment scenarios, each WLAN is mapped to a single dynamic interface per WLC.
However, consider a deployment scenario where there is a 4404-100 WLC supporting the maximum
number of APs (100). Now consider a scenario where 25 users are associated to each AP. That would
result in 2500 users sharing a single VLAN. Some customer designs may require substantially smaller
subnet sizes. One way to deal with this is to break up the WLAN into multiple segments. The WLC’s AP
grouping feature allows a single WLAN to be supported across multiple dynamic interfaces (VLANs)
on the controller. This is done by taking a group of APs and mapping them to a specific dynamic
interface. APs can be grouped logically by employee workgroup or physically by location.
However, consider a deployment scenario where there is a 4404-100 WLC supporting the maximum
number of APs (100). Now consider a scenario where 25 users are associated to each AP. That would
result in 2500 users sharing a single VLAN. Some customer designs may require substantially smaller
subnet sizes. One way to deal with this is to break up the WLAN into multiple segments. The WLC’s AP
grouping feature allows a single WLAN to be supported across multiple dynamic interfaces (VLANs)
on the controller. This is done by taking a group of APs and mapping them to a specific dynamic
interface. APs can be grouped logically by employee workgroup or physically by location.
illustrates the use of AP groups based on site-specific VLANs.
Note
AP groups do not allow multicast roaming across group boundaries; this is discussed in more detail later
in this design guide.
in this design guide.