Multiple Controllers; Increasing Mesh Availability - Cisco Mesh Access Points Deployment Manual

Site Preparation and Planning

Increasing Mesh Availability

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 RAP, 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, you should
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.
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 Cell Planning Distance section, a wireless mesh cell of one square mile was 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 process is done by adding a RAP to the cell. Similar to the
larger mesh deployment, the decision is whether to use RAP on the same channel, as shown in Figure 41:
Two RAPs per Cell with the Same Channel, on page 96, or to use RAPs placed on different channels, as
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