Wireless Mesh Mobility Groups; Increasing Mesh Availability - Cisco aironet 1522 Design And Deployment Manual

Wireless Mesh Mobility Groups

Keep in mind that a wireless mesh network built using the maximum number of controllers in a mobility
group is not truly the maximum size of WLAN coverage because this is simply the maximum size of the
mobility group. The WLANs that are part of a mobility group can be replicated in another mobility
group, and a WLAN client is able to roam between these mobility groups.
Roaming between mobility groups is done at Layer 3 roaming.
Multiple Controllers
The consideration in distance of the CAPWAP controllers from other CAPWAP controllers in the
mobility group, and the distance of the CAPWAP controllers from the RAPs, is similar to the
consideration of an CAPWAP WLAN deployment in an enterprise.
There are operational advantages to centralizing CAPWAP controllers, and these advantages need to be
traded off against the speed and capacity of the links to the CAPWAP APs and the traffic profile of the
WLAN clients using these mesh access points.
If the WLAN client traffic is expected to be focused on particular sites such as the Internet or a data
center, centralizing the controllers at the same sites as these traffic focal points gives the operational
advantages without sacrificing traffic efficiency.
If the WLAN client traffic is more peer-to-peer, a distributed controller model might be a better fit. It is
likely that a majority of the WLAN traffic are clients in the area, with a smaller amount of traffic going
to other locations. Given that many peer-to-peer applications can be sensitive to delay and packet loss,
it is best to ensure that traffic between peers takes the most efficient path.
Given that most deployments see a mix of client-server traffic and peer-to peer traffic, it is likely that a
hybrid model of CAPWAP controller placement is used, where points of presence (PoPs) are created
with clusters of controllers placed in strategic locations in the network.
In all cases, remember that the CAPWAP model used in the wireless mesh network is designed for
campus networks; that is, it expects a high-speed, low-latency network between the CAPWAP mesh
access points and the CAPWAP controller.

Increasing Mesh Availability

In the
created and then built upon. This wireless mesh cell has similar properties to the cells used to create a
cellular phone network because the smaller cells (rather than the defined maximum cell size) can be
created to cover the same physical area, providing greater availability or capacity. This is done by adding
RAPs to the cell. Just as in the larger mesh deployment, the decision is whether to use RAPs on the same
channel, as shown in
addition of RAPs into an area adds capacity and resilience to that area.
Cisco Aironet 1520, 1130, 1240 Series Wireless Mesh Access Points, Design and Deployment Guide, Release 6.0
OL-20213-01
"Cell Planning and Distance" section on page
Figure 34, or to use RAPs placed on different channels, as shown in
Site Preparation and Planning
43, a wireless mesh cell of one square mile was
Figure 35. The
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