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Mobility controller: A mobility controller provides mobility management tasks including interswitch peer
group roaming, RRM, and guest access. One mobility controller is required for each mobility subdomain.
A Cisco Catalyst 3850 switch can serve as a mobility controller for small to medium-sized deployments. For
large deployments, a dedicated WLC such as the 5760 WLC or WiSM2/5508 WLC with a software update is
required.
Mobility roaming, in which a wireless client moves from one physical location to another without losing connectivity
and services at any time, can be managed by a single mobility controller if roaming is limited to a small number of
access points that are physically located together. Roaming among a large number of access points can be
managed by multiple mobility controllers in a mobility group.
The Cisco Unified Access mobility architecture benefits include:
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Scalability: The converged access deployments allow a highly scalable design for small, medium, and
large customer deployments. Furthermore, the entire network delivers high performance for any sized
deployments enabled by the new Cisco Catalyst 3850 switch that provides high wireless bandwidth starting
at the network edge and by separation of wireless data plane versus control plane, which allows traffic
optimization.
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Deterministic policy consistency: By default, all roams (whether across a Layer 3 boundary or not) carry
the end user traffic from their roamed-to switch (where the user’s current wireless traffic terminates) back to
the original switch through which the user initially associated. By doing so, the user’s policy enforcement
point remains fixed by the initial switch, and roam times are more deterministic as the user continues to
move around. However, this default behavior can be modified using a setting to allow for a policy
enforcement point to be moved to a new switch where the roaming user’s current association is.
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Efficiency: Mobility agents can be fully meshed and autocreated within a group. Mobility controllers are
also fully meshed within a mobility group. Roamed traffic within a group of access points moves directly
between the mobility agents in that group. Roamed traffic between different groups of access points moves
using the mobility controllers servicing those groups.
Understanding Quality of Service in Converged Access Mode
Converged access enables a new level of consistent, granular, and multilevel QoS capabilities for the converged
wired and wireless infrastructure. In a traditional network, QoS policies are applied on a wireless LAN controller,
while wired policies are applied on a switch port. There was no consistency between wired and wireless QoS
policies. QoS definition, granularity, and behavior mismatch between wired and wireless caused many network
performance problems. It became very difficult to match QoS behavior across different access types. With the new
converged access architecture, both wired and wireless QoS policing policies are implemented on the Cisco
Catalyst 3850 switch and on the converged data traffic, thereby providing simplicity of management for the network
administrator and consistent experience for the end user. See Figure 3 for details.