Passive Client

What is Passive Client?

Passive client (Passive Client) is a wireless device configured with a static IP address, such as scales, printers, and Configuring VMware virtual machine a static address and so on. These clients associated with the AP, IP will not transmit any information. As a result, when using a passive client, unless these clients to use DHCP way, otherwise the WLC will not be used to support its IP address.

 

Cisco WLC currently acts as a proxy ARP Requests. Upon receiving the ARP request, Cisco WLC will respond to ARP Response, rather than directly transmitting the request to the client. This has two advantages:

• Sends ARP request upstream to the client device does not know the location of the client.
• Saving devices (such as mobile phones and printers) with a battery powered power supply, because they do not respond to every ARP request.

 

Because the wireless controller does not have any IP-related information about passive client, so it can not respond to any ARP request. The current behavior does not allow passive ARP request to the client. Any attempt to access a passive client application will fail.

 

Passive Client feature that the ARP request and response exchange between a wired and wireless clients. When enabled, this feature allows the controller to the ARP request is transmitted from a wired client to the wireless client, until the desired wireless client enters the RUN state.

 

Passive Client Configuration

注意：To configure passive clients, you must enable multicast-multicast or multicast-unicast mode.

Reference: https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-5/config-guide/b_cg85/wlan_interfaces.html?bookSearch=true

 

Third-Party WGBs and Client VMs

Information About Non-Cisco Workgroup Bridges

When a Cisco workgroup bridge (WGB) is used, the WGB informs the access points of all the clients that it is associated with. The controller is aware of the clients associated with the access point. When non-Cisco WGBs are used, the controller has no information about the IP address of the clients on the wired segment behind the WGB. Without this information, the controller drops the following types of messages:

• ARP REQ from the distribution system for the WGB client
• ARP RPLY from the WGB client
• DHCP REQ from the WGB client
• DHCP RPLY for the WGB client

The following are some guidelines for non-Cisco workgroup bridges:

• The controller can accommodate non-Cisco WGBs so that the controller can forward ARP, DHCP, and data traffic to and from the wired clients behind workgroup bridges by enabling the passive client feature. To configure your controller to work with non-Cisco WGBs, you must enable the passive client feature so that all traffic from the wired clients is routed through the WGB to the access point. All traffic from the wired clients is routed through the work group bridge to the access point.

Note	For FlexConnect APs in local switching, non-Cisco workgroup-bridge clients in bridged mode are supported using the config flexconnect group group-name dhcp overridden-interface enable command.

• When a WGB wired client leaves a multicast group, the downstream multicast traffic to other WGB wired clients is interrupted briefly.
• If you have clients that use PC virtualization software such as VMware, you must enable this feature.

Note	We have tested multiple third-party devices for compatibility but cannot ensure that all non-Cisco devices work. Support for any interaction or configuration details on the third-party device should be discussed with the device manufacturer.

• You must enable the passive client functionality for all non-Cisco workgroup bridges.
• You might need to use the following commands to configure DHCP on clients:

• Disable DHCP proxy by using the config dhcp proxy disable command.
• Enable DHCP boot broadcast by using the config dhcp proxy disable bootp-broadcast enable command.

 

Restrictions for Non-Cisco Workgroup Bridges

• Only Layer 2 roaming is supported for WGB devices.
• Layer 3 security (web authentication) is not support for WGB clients.
• Visibility of wired hosts behind a WGB on a controller is not supported because the non-Cisco WGB device performs MAC hiding. Cisco WGB supports IAPP.
• ARP poisoning detection does not work on a WLAN when the flag is enabled.
• VLAN select is not supported for WGB clients.
• Some third-party WGBs need to operate in non-DHCP relay mode. If problems occur with the DHCP assignment on devices behind the non-Cisco WGB, use the config dhcp proxy disable and config dhcp proxy disable bootp-broadcast disable commands.

The default state is DHCP proxy enabled. The best combination depends on the third-party characteristics and configuration.