Руководство По Проектированию для Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter
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Enterprise Mobility 4.1 Design Guide
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Chapter 12 Cisco Unified Wireless and Mobile IP
Roaming on a Cisco Unified Wireless Network
the client, acting as its own FA, receives a new DHCP IP address and informs the HA it has a new
location. At this time, the HA can then build a tunnel to the client for forwarding packets. This is called
a collocated care of address.
location. At this time, the HA can then build a tunnel to the client for forwarding packets. This is called
a collocated care of address.
Move discovery is done in the Cisco Unified Wireless Network by the network that knows which AP the
wireless client is currently associated to. Update signaling is done by the first packets sent to the WLC
from the wireless client. The Update process is described in detail in
wireless client is currently associated to. Update signaling is done by the first packets sent to the WLC
from the wireless client. The Update process is described in detail in
For more information, see the following URL:
Path Re-establishment
Path re-establishment is the mechanism used to allow the client to receive packets that are destined for
it from the HA that contains the location database. Typically a tunneling mechanism is used to
encapsulate the original packet. In the Cisco Unified Wireless Network, packets are forwarded to
wireless clients on associated APs through the “always up” LWAPP tunnel. For wireless clients that have
roamed to another WLC, the WLCs use a dynamic Ethernet-over-IP tunnel for all packets forwarded to
other WLCs in the mobility group.
it from the HA that contains the location database. Typically a tunneling mechanism is used to
encapsulate the original packet. In the Cisco Unified Wireless Network, packets are forwarded to
wireless clients on associated APs through the “always up” LWAPP tunnel. For wireless clients that have
roamed to another WLC, the WLCs use a dynamic Ethernet-over-IP tunnel for all packets forwarded to
other WLCs in the mobility group.
In Mobile IP, there are several types of tunnels available (GRE, UDP, and IP in IP) and the type of tunnel
used depends on the equipment between the Mobile IP Client and HA, and whether the HA supports that
type of encapsulation. For example, if the HA detects that the client is behind a NAT gateway, it uses
UDP tunneling. If the Mobile IP Client requests GRE tunneling and the HA can support the tunneling,
it uses GRE. Typically, the Mobile IP Client requests IP in IP tunneling, and all RFC-compliant clients
can support this type of tunneling.
used depends on the equipment between the Mobile IP Client and HA, and whether the HA supports that
type of encapsulation. For example, if the HA detects that the client is behind a NAT gateway, it uses
UDP tunneling. If the Mobile IP Client requests GRE tunneling and the HA can support the tunneling,
it uses GRE. Typically, the Mobile IP Client requests IP in IP tunneling, and all RFC-compliant clients
can support this type of tunneling.
Roaming on a Cisco Unified Wireless Network
A Cisco Unified Wireless Network acts as a mobility proxy for the wireless client. This allows the
network to provide seamless mobility to the wireless client without any extra software or additional
configuration on the wireless client (see
network to provide seamless mobility to the wireless client without any extra software or additional
configuration on the wireless client (see
When a wireless client associates to an AP, the AP forwards the client packets to the WLC via the
LWAPP tunnel set up between the WLC and AP (the LWAPP tunnel is set up between the AP and WLC
at AP boot time). For the WLC, the LWAPP tunnel allows it to do the following:
LWAPP tunnel set up between the WLC and AP (the LWAPP tunnel is set up between the AP and WLC
at AP boot time). For the WLC, the LWAPP tunnel allows it to do the following:
•
Know to which AP the client is associated (LWAPP tunnel endpoint)
•
Forward packets back to the client via the tunnel
•
Be multiple hops away from the AP and still receive the client traffic
•
Filter the packets to and from the wireless client
For the client, the LWAPP tunnel allows the client to see its default gateway as being one hop away, even
though it might physically be several hops away.
though it might physically be several hops away.