270 Configuring APs

NN47250-500 (Version 03.01)
3If the AP is unable to locate a WSS on the subnet it is connected to, and is unable to find a WSS based on
information in the DHCP option 43 field, the AP sends DNS requests for the wlan-switch, where the DNS
suffix for mynetwork.com is learned through DHCP.
4The DNS server replies with the system IP address of a WSS.
●If only wlan-switch is defined in DNS, the AP sends a unicast Find WSS message to the WSS whose
IP address is returned for wlan-switch.
5The AP sends Find WSS requests to the WSS IP addresses given by the DNS reply. If a WSS receives the
Find WSS Request, the process continues with step 6.
However, if no WSSs reply, the AP repeatedly retries this method:
●If still no WSSs reply, the AP begins the process again, starting with the procedure under “How a
distributed AP contacts a WSS (DHCP-obtained address)” on page 269, on the other AP port.
●If the other AP port does not have a link or the AP has only one port, the AP instead restarts, and
begins the process again on the same AP port.
6The WSS that receives the Find WSS request determines the best WSS for the AP to use, based on the
bias settings for the AP on each switch. If more than one switch has high bias for the AP or all switches
have the same bias, the WSS suggests the switch that has the highest capacity to add new active AP
connections.
7The WSS sends a unicast Find WSS Reply message to the AP containing the system IP address of the
best WSS to use.
8The AP sends a unicast message to the suggested WSS, to request an operational image. If the AP does
not receive a reply after 10 seconds, the AP reboots and starts the boot process over.
If an AP does not receive a reply to a DNS request or a request for an operational image after one minute, the AP starts
the boot process over with a new DHCP Discover message, this time from AP port 2.

How a distributed AP contacts a WSS (statically configured address)

When configuring a distributed AP with static IP information, you can specify the following information:
AIP address, subnet mask, default router, and whether the configured static IP address information is
enabled for the AP.
BThe IP address of a suitable WSS for the AP to use as a boot device.
CThe fully qualified domain name of a WSS to use as a boot device, and the IP address of a DNS server
used to resolve the WSS’s name.
This information is used in the following way when the AP attempts to contact a WSS:
1If Items A and B (but not Item C) are specified, and the WSS’s IP address is part of the local subnet, then
the AP sends an ARP request for its configured static IP address, to ensure that it is not already in use in
the network. The AP then sends a Find WSS message to UDP port 5000 at the WSS’s IP address.
●If the AP receives a response from that address, it sends a unicast message to the WSS, to request an
operational image.
Note. You must configure a DNS address record on your DNS server for the
WSS IP address. Otherwise, the DNS server cannot provide the WSS’s address to
the AP.