534| Access Points AOS-W 6.5.3.x| User Guide
n Switch addresses derived from the server-name and server-ip provisioning parameters and the default
switch name aruba-master are added to the list. Note that if a DNS name resolves to multiple addresses,
all addresses are added to the list.
Switch Discovery using DNS
When using DNS, AP learns multiple IP addresses to associate with a switch. If the primary switch is unavailable
or does not respond, the AP continues through the list of learned IP addresses until it establishes a connection
with an available switch. This takes approximately 3.5 minutes per switch.
It is recommended you use a DNS server to provide APs with the IP address of the master switch because it involves
minimal changes to the network and provides the greatest flexibility in the placement of APs.
APs are factory-configured to use the host name aruba-master for the master switch. For the DNS server to
resolve this host name to the IP address of the master switch, you must configure an entry on the DNS server
for the name aruba-master.
Switch Discovery using ADP
ADP is enabled by default on all Alcatel-Lucent APs and switches. With ADP, APs send out periodic multicast
and broadcast queries to locate the master switch. ADP requires that all APs and switches are connected to the
same Layer-2 network. If the devices are on different networks, you must use a Layer-3 compatible discovery
mechanism, such as DNS, DHCP, or IGMP forwarding.
To use ADP discovery:
1. Issue the command show adp config to verify that ADP and IGMP join options are enabled on the switch,
If ADP is not enabled, you can reenable ADP using the command adp discovery enable and adp igmp-
join enable.
2. If the APs are not in the same broadcast domain as the master switch, you enable multicast on the network
(ADP multicast queries are sent to the IP multicast group address 239.0.82.11) for the switch to respond to
the APs’ queries. You also must make sure that all routers are configured to listen for Internet Group
Management Protocol (IGMP) join requests from the switch and can route these multicast packets. C
Switch discovery using a DHCP Server
You can configure a DHCP server to provide the master switch’s IP address. You must configure the DHCP
server to send the switch’s IP address using the DHCP vendor-specific attribute option 43. The APs identify
themselves with a vendor class identifier set to Alcatel-LucentAP in their DHCP requests. When the DHCP
server responds to a request, it will send the switch’s IP address as the value of option 43.
When using DHCP option 43, the AP accepts only one IP address. If the IP address of the switch provided by
DHCP is not available, the AP can use the other IP addresses provisioned or learned by DNS to establish a
connection. For more information on how to configure vendor-specific information on a DHCP server, see
DHCP with Vendor-Specific Options on page 1102 or refer to the documentation included with your server.
Enable DHCP to Provide APs with IP Addresses
Each AP requires a unique IP address on a subnetwork that has connectivity to a switch. It is recommended
you use the Dynamic Host Configuration Protocol (DHCP) to provide IP addresses for APs; the DHCP server
can be an existing network server or an switch configured as a DHCP server.
If you do not enable DHCP, each AP must be manually configured with an IP address through the AP provisioning
profile. For details, see .
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