4
If the MAP does not find a Wireless Switch using the Find WX broadcast method, and
the DHCP Ack message contained a list of Wireless Switch IP addresses or hostnames in
DHCP option 43, the MAP contacts the Wireless Switches:
If the DHCP Ack message contained a list of IP addresses, in DHCP option 43, the
MAP sends a unicast Find WX message to each address.
If the DHCP Ack message contained a list of hostnames in DHCP option 43, the MAP
sends DNS Requests to the DNS server for the IP addresses of the switches and then
sends a unicast Find WX message to each address.
Each Wireless Switch that receives a unicast Find WX message from the MAP determines
the best Wireless Switch for the MAP to use based on the bias settings for the MAP on
each switch. If more than one switch has high bias for the MAP or all switches have the
same bias, the switch suggests the switch that has the highest capacity to add new
active MAP connections. The Wireless Switch sends a unicast Find WX Reply message to
the MAP containing the system IP address of the best Wireless Switch to use.
The MAP sends a unicast message to the Wireless Switch suggested by the Find WX
Reply message, to request a software image and configuration.
If no Wireless Switches reply, the MAP resends the Find WX messages up to 11 more
times. If no Wireless Switches reply after all 12 attempts, the MAP tries to find a
Wireless Switch using the third and final method.
DNS Request for 3COMWX.mynetwork.com
This is the third method the MAP uses to try to find a Wireless Switch.
If the MAP is unable to locate a Wireless Switch on the subnet it is connected to, and is
unable to find a WX based on DHCP option 43, the MAP sends a DNS request for
3COMWX.mynetwork.com, where the domain name 'mynetwork.com' is learned
through DHCP. This method requires a DNS address record on the DNS server that maps
a Wireless Switch IP address to 3COMWX.mynetwork.com.
The DNS server replies with the system IP address of a Wireless Switch.
The MAP sends a unicast Find WX message to the Wireless Switch whose IP address was
returned by the DNS server. The Wireless Switch determines the best Wireless Switch for
the MAP to use based on the bias settings for the MAP on each switch. If more than one
switch has high bias for the MAP or all switches have the same bias, the switch suggests
the switch that has the highest capacity to add new active MAP connections. The
Wireless Switch sends a unicast Find WX Reply message to the MAP containing the
system IP address of the best Wireless Switch to use.
The MAP sends a unicast message to the Wireless Switch suggested by the Find WX
Reply message, to request a software image and configuration.
If no Wireless Switches reply, the MAP retries this method up to 11 more times. If no
Wireless Switches reply after all 12 attempts, the MAP begins the process again with the
DHCP Exchange.
A MAP that is directly connected to a PoE port on a WX1200 switch follows the same basic procedure.
The switch replies to the DHCP Discover and Find WX Broadcast messages sent by the MAP, thus
providing its configuration. The IP address used for communication with a directly connected MAP is
private to the link and is not visible anywhere else on the network.
