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Created Mar 17, 2013 13:16:24
WLAN-ESS interface is a virtual Layer 2 interface. Similar to a hybrid Layer 2 Ethernet interface. A WLAN-ESS interface has Layer 2 attributes and supports multiple Layer 2 protocols. It provides a template for configuring a WLAN-DBSS interface. You can set WLAN-ESS interface parameters, which are then applied to the WLAN-DBSS interface on the WLAN-ESS interface.
WLAN-DBSS interface is a mapping to a VAP on an AC.A WLAN-DBSS interface corresponds to a VAP,and service attributes of the VAP are configured on its WLAN-DBSS interface. The WLAN-DBSS interface inherits the attributes of its WLAN-ESS interface. The WLAN module on a wireless switch dynamically allocates a WLAN-DBSS interface on a WLAN-ESS interface to each wireless service. After the wireless service becomes invalid, the WLAN module deletes its WLAN-DBSS interface.
WLAN-DBSS interface is a logical interface on an AC. During login, wireless users need to send Dot1x packets, DHCP packets, ARP packets, and Layer 2 multicast packets. These packets need to be forwarded by a WLAN-DBSS interface.
When an AC receives a data packet from a wireless user, the AC checks whether the packet is encapsulated with a CAPWAP header. If not, the AC forwards the packet through a WLAN-DBSS interface. If so, the AC strips the CAPWAP header from the packet and then forwards the packet through a WLAN-DBSS interface.
When an AC receives packets that need to be forwarded to wireless users, the AC adds a WLAN-DBSS interface ID to the packets, making the WLAN-DBSS interface become the outbound interface of these packets. Then,the AC checks whether the packets are multicast or broadcast packets. If so, the AC forwards the packets through an XGE interface but not the WLAN-BSS interface. If not, the AC determines whether the packets need to be encapsulated with a CAPWAP header.If so, the AC encapsulates the packets as UDP packets and forwards them. If not, the AC encapsulates the packets as Ethernet packets and forwards them through an XGE interface but not the WLAN-DBSS interface.
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