Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter Guida Alla Progettazione
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Enterprise Mobility 4.1 Design Guide
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Chapter 6 Cisco Unified Wireless Multicast Design
Overview of Multicast Forwarding in Cisco Unified Wireless Networks
forward the packet to. When the AP receives the LWAPP packet, it strips off the outer LWAPP
encapsulation and transmits the multicast packet to the WLAN (on all radios associated to the WLAN)
identified in the LWAPP WLAN ID bitmask.
encapsulation and transmits the multicast packet to the WLAN (on all radios associated to the WLAN)
identified in the LWAPP WLAN ID bitmask.
Figure 6-1
Multicast Forwarding Mechanism in Version 4.1 and Below
Effectively, an LWAPP multicast group is used to deliver the multicast packet to each access point. This
allows the routers in the network to use standard multicast techniques to replicate and deliver multicast
packets to the APs. For the LWAPP multicast group, the controller becomes the multicast source and the
APs become the multicast receivers.
allows the routers in the network to use standard multicast techniques to replicate and deliver multicast
packets to the APs. For the LWAPP multicast group, the controller becomes the multicast source and the
APs become the multicast receivers.
Note
A prerequisite for using the new multicast performance functionality is that a multicast enabled network
is configured on all routers between the controllers and the APs. To accommodate networks that do not
support multicast, the controller continues to support the original unicast packet forwarding mechanism.
is configured on all routers between the controllers and the APs. To accommodate networks that do not
support multicast, the controller continues to support the original unicast packet forwarding mechanism.
Note
With multicast enabled, any kind of multicast packet received on the VLAN from the first hop router is
transmitted over the wireless including HSRP hellos, all router, EIGRP, and PIM multicast packets.
transmitted over the wireless including HSRP hellos, all router, EIGRP, and PIM multicast packets.
After the administrator enables multicast (multicast mode is disabled by default) and configures an
LWAPP multicast group, the access points downloads the controller’s LWAPP multicast group address
during the normal join process (at boot time) to the controller. After an access point joins a controller
and downloads its configuration, the AP issues an Internet Group Management Protocol (IGMP) join
request to join the controller’s LWAPP multicast group. This triggers the normal setup for the multicast
state in the multicast-enabled routers between the controller and APs. The source IP address for the
multicast group is the controller’s management interface IP address, not the AP-manager IP address used
for Layer 3 mode. Once the AP has joined the controllers LWAPP multicast group, the multicast
algorithm for client multicast traffic works as described below.
LWAPP multicast group, the access points downloads the controller’s LWAPP multicast group address
during the normal join process (at boot time) to the controller. After an access point joins a controller
and downloads its configuration, the AP issues an Internet Group Management Protocol (IGMP) join
request to join the controller’s LWAPP multicast group. This triggers the normal setup for the multicast
state in the multicast-enabled routers between the controller and APs. The source IP address for the
multicast group is the controller’s management interface IP address, not the AP-manager IP address used
for Layer 3 mode. Once the AP has joined the controllers LWAPP multicast group, the multicast
algorithm for client multicast traffic works as described below.
When the source of the multicast group is on the wired LAN:
•
When the controller receives a multicast packet from any of the client VLANs on the first hop router,
it transmits the packet to the LWAPP multicast group via the management interface at the best effort
QoS classification. The QoS bits for the LWAPP multicast packet are hard coded at the lowest level
and are not user changeable.
it transmits the packet to the LWAPP multicast group via the management interface at the best effort
QoS classification. The QoS bits for the LWAPP multicast packet are hard coded at the lowest level
and are not user changeable.
222287
LWAPP
LWAPP
LWAPP
LWAPP
One LWAPP
multicast packet out.
multicast packet out.
Network replicates
packets as needed.
packets as needed.
One multicast packet in.
LWAPP Multicast
Group