Configuring APs 269

Nortel WLAN—Security Switch 2300 Series Configuration Guide
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.
These items are referred to by letter in the description of how the AP contacts a WSS in “How a distributed AP contacts
a WSS (statically configured address)” on page 270. If the AP does not have static IP address information configured, or
its static IP configuration is disabled, then the AP obtains its IP address through DHCP.

Contacting a WSS

After the AP has an IP address, it attempts to contact a WSS on the network. The method used for contacting a WSS
depends on whether the AP’s IP address was obtained through DHCP or was configured statically.

How a distributed AP contacts a WSS (DHCP-obtained address)

1If the DHCP Offer message contained WSS IP addresses or hostnames in the Option 43 field, the AP
proceeds as follows:
If the DHCP Offer message contained one or more IP addresses in the Option 43 field, the AP sends
a unicast Find WSS message to each address. The process skips to step 6.
If the DHCP Offer message contained one or more hostnames in the Option 43 field, the AP sends
DNS Requests to the DNS server for the IP addresses of the hosts, then sends a unicast Find WSS
message to each address. The process skips to step 6.
If no WSSs reply, the AP repeatedly resends the Find WSS messages. If no WSSs reply, the process
continues with step 3.
2If no IP addresses or hostnames were specified in the Option 43 field of the DHCP Offer message, the AP
sends a Find WSS message to UDP port 5000 on the subnet broadcast address.
WSSs in the same IP subnet as the AP receive the message and respond with a Find WSS Reply
message.
If the AP is configured as a Distributed AP on a switch and the connection bias is high, the
WSS immediately sends a Find WSS Reply message.
If the AP is configured as a Distributed AP on a switch but the connection bias is low, that WSS
waits one second, then sends a Find WSS Reply message. The delay allows switches with high
bias for the AP to respond first.
If a WSS that receives the Find WSS message does not have the Distributed AP in its
configuration but another WSS in the same Mobility Domain does, the switch waits two
seconds, then sends a Find WSS Reply message with the IP address of the best switch to use.
The determination of best switch is based on the bias settings for the AP on each switch and on
the capacity of each switch to add new active AP connections.
The process skips to step 6.
If no WSSs reply, the AP repeatedly resends the Find WSS broadcast. If still no WSSs reply, the
process continues with step 3.
Note. This method requires DNS address records on the DNS server that map
the hostnames to the WSS IP addresses.