Wireless users at the headquarters of a large healthcare provider were experiencing difficulties connecting to the network. The connectivity problems were isolated to a single AP, and to only users that required DHCP functionality. The problem appeared to be an AP issue.
Problems are not always as they appear. A quick re-assessmnet of AP coverage with Ekahau Site Survey indicated no problems in this area. Using the distributed power of WildPackets Distributed Network Analysis, the customer initiated multiple data captures. One capture, using OmniPeek Enterprise and its ability to capture and analyze wireless traffic, was initiated near the wireless clients experiencing the problem. A second capture was initiated from an OmniEngine software probe, installed on a dedicated Windows-based server that analyzed wired traffic from the wireless access point to the edge switch. An Omnipliance network recorder capturing and analyzing data 24/7 between the wired traffic from the edge switch to the network's core switch was also utilized. A client was then rebooted to invoke the entire wireless authentication and connection process. During this process all three data captures were concurrently monitored using the OmniPeek Enterprise console.
The results indeed confirmed that things are not always as they seem. The wireless capture indicated no anomalies, as did the wired capture from the AP to the edge switch. However, OmniPeek analysis of the data on the third capture clearly illustrated that the edge switch was not forwarding DHCP packets to the core network where the DHCP server was running. Clients were therefore never receiving DHCP addresses, and could not connect to the network.