Руководство По Проектированию для Cisco Cisco Aironet 350 Mini-PCI Wireless LAN Client Adapter
2-22
Enterprise Mobility 4.1 Design Guide
OL-14435-01
Chapter 2 Cisco Unified Wireless Technology and Architecture
Broadcast and Multicast on the WLC
In the protocol traces above, a symmetrical mobility tunnel (EtherIP) is established between two WLCs,
10.15.9.11 (anchor) and 10.15.9.13 (foreign). In
10.15.9.11 (anchor) and 10.15.9.13 (foreign). In
, client 10.20.32.100, which has roamed to
an AP on controller 10.15.9.13, is sending an ICMP ping request to Internet site 208.131.36.158
(
(
yahoo.com
). Note that the foreign controller tunnels the client’s packet to the anchor controller. If the
controllers were configured for asymmetrical mobility tunneling, this packet would not appear in the
trace because the foreign controller would have forwarded it locally out the VLAN interface associated
with the WLAN. In
trace because the foreign controller would have forwarded it locally out the VLAN interface associated
with the WLAN. In
, the ping reply is received by the anchor controller and forwarded to the
foreign controller via same the mobility tunnel, which is the same as the asymmetrical tunnel.
Important Notes About Layer 3 Roaming
Layer 3 roaming is a highly useful capability, but when deploying with the 4.1 software release,
remember the following points:
remember the following points:
•
Multicast group membership is not currently transferred during the client roam; that is, if a client is
receiving a multicast stream and roams to a foreign WLC that multicast stream is broken, and must
be re-established.
receiving a multicast stream and roams to a foreign WLC that multicast stream is broken, and must
be re-established.
•
The foundation for facilitating Layer 3 roaming within the Unified Wireless solution is based on the
concept of mobility anchors and EoIP tunnels. An ‘anchor WLC’ is that WLC through which a client
first associates to a WLAN. The client is then assigned an address, via DHCP, that corresponds to
the interface/subnet assigned to the WLAN at the anchor controller. Currently, the Unified Wireless
solution does not permit clients to connect to a WLAN with a static IP address that is outside the
subnet defined for the WLAN. In deployment scenarios where static client addressing is necessary,
Mobile IP should be investigated as a potential solution. For more details concerning Mobile IP and
its compatibility with the Cisco Unified Wireless architecture, see
concept of mobility anchors and EoIP tunnels. An ‘anchor WLC’ is that WLC through which a client
first associates to a WLAN. The client is then assigned an address, via DHCP, that corresponds to
the interface/subnet assigned to the WLAN at the anchor controller. Currently, the Unified Wireless
solution does not permit clients to connect to a WLAN with a static IP address that is outside the
subnet defined for the WLAN. In deployment scenarios where static client addressing is necessary,
Mobile IP should be investigated as a potential solution. For more details concerning Mobile IP and
its compatibility with the Cisco Unified Wireless architecture, see
Broadcast and Multicast on the WLC
The section discusses the handling of broadcast and multicast traffic by a WLC and its impact on design.
802.11 broadcast frame, it is unicasted to the AP. The AP then sends the frame as a broadcast out both
its wireless and wired interfaces.
its wireless and wired interfaces.