Configuring APs 203Nortel WLAN—Security Switch 2300 Series Configuration GuideAs part of the boot process, an AP disables and reenables the link on the port over which the AP is attempting to boot. IfSTP is enabled on the device that is directly connected to the port, the link state change can cause the port on the otherdevice to leave the forwarding state and stop forwarding traffic. The port remains unable to forward traffic for theduration of the STP forwarding delay.An AP waits 30 seconds to receive a reply to its DHCP Discover message, then tries to boot using the other AP port. Ifthe boot attempt fails on the other port also, the AP then reattempts to boot on the first port. The process continues untila boot attempt is successful. If STP prevents the other device’s port from forwarding traffic during each boot attempt, theAP repeatedly disables and reenables the link, causing STP to repeatedly stop the other device’s port from forwardingtraffic. As a result, the boot attempt is never successful.To allow an AP to boot over a link that has STP enabled, do one of the following on the other device:• Disable STP on the other device’s port.• Enable the port fast convergence feature, if supported, on the other device’s port. (On some vendors’ devices, thisfeature is called PortFast.)• If the other device is running Rapid Spanning Tree or Multiple Spanning Tree, set the port into edge port mode.Distributed APs and DHCP option 43The option 43 field in a DHCP Offer message can provide a simple and effective way for APs to find WSSs across anintermediate Layer 3 network, and is especially useful in networks that are geographically distributed or have a flatdomain name space. You can use the DHCP option 43 field to provide a list of WSS IP addresses, without the need toconfigure DNS servers.To use DHCP option 43, configure the option to contain a comma-separated list of WSS IP addresses or hostnames, inthe following format:ip:ip-addr1,ip-addr2,...orhost:hostname1.mynetwork.com, hostname2.mynetwork.com,...You can use an IP address list or a hostname list, but not both. If the list contains both types of values, the AP does notattempt to use the list.The ip and host keywords can be in lowercase, uppercase (IP or HOST), or mixed case (example: Ip, Host, and so on.)You can use spaces after the colon or commas, but spaces are not supported within IP addresses or hostnames. Leadingzeroes are supported in IP addresses. For example, 100.130.001.1 is valid.Valid characters in hostnames are uppercase and lowercase letters, numbers, periods ( . ), and hyphens ( - ). Other char-acters are not supported.If you use the host option, you must configure the network’s DNS server with address records that map the hostnames inthe list to the WSS IP addresses.After receiving a DHCP Offer containing a valid string for option 43, a Distributed AP sends a unicast Find WSSmessage to each WSS in the list. See “How a distributed AP contacts a WSS (DHCP-obtained address)” (page 209) for adescription of this process.No configuration is required on the WSS itself.
