Theory of Operation 25

Wireless Client APs recognize wireless clients as they associate with the AP. The AP keeps a list of Association Process the wireless clients it services. Wireless clients associate with an AP based on the

following conditions:

■Signal strength between the AP and wireless client

■Wireless clients currently associated with the AP

■Wireless client Supported Rate (see the table below)

■Positive match between the wireless client and encryption keys (optional)

■Positive wireless client authorization by the Access Control List (optional)

The following table gives the wireless client support rates:

Data Rate

Requirement

 

 

11 Mbps

Optional

5.5 Mbps

Optional

2 Mbps

Optional

1 Mbps

Required

 

 

Wireless clients perform preemptive roaming by intermittently scanning for APs and associating with the best available AP. Before roaming and associating with APs, wireless clients perform scans to collect AP statistics and determine the direct-sequence channel used by the AP.

Scanning is a periodic process where the wireless client sends out messages on all frequencies defined by the country code. The statistics enable a wireless client to reassociate by synchronizing its frequency to the AP. The wireless client continues communicating with that AP until it needs to switch cells or roam.

Wireless clients perform scans at start-up. In a scan, a wireless client uses a sequential set of channels as the scan range. For each channel in range, the wireless client tests for Clear Channel Assessment (CCA). When a transmission-free channel becomes available, the wireless client broadcasts a probe with the wireless LAN service area and the broadcast HSA_ID. An AP-directed probe response generates a wireless client Acknowledgment (ACK) and the addition of the AP to the AP table with a proximity classification. An unsuccessful AP packet transmission generates another wireless client probe on the same channel. If the wireless client fails to receive a probe response within the time limits, it repeats the probe process on the next channel in the sequence. This process continues through all channels in the range.

A wireless client can roam within the coverage area by switching APs. Roaming is transparent and virtually instantaneous in high-level applications. Roaming occurs when:

■An unassociated wireless client attempts to associate or reassociate with an available AP.

■The supported rate changes or the wireless client finds a better transmit rate with another AP.

■The signal quality of a potential AP exceeds that of the current AP.

Page 24 Page 26
Page 25
Image 25
3Com 09-1765-001 manual Data Rate Requirement
Page 24 Page 26

09-1765-001 specifications

The 3Com 09-1765-001 is a versatile and robust networking device designed to enhance various aspects of enterprise network environments. Known for its reliability and performance, this product stands out in the competitive field of networking hardware, making it a preferred choice for businesses aiming to optimize their network infrastructure.

One of the main features of the 3Com 09-1765-001 is its support for advanced network management protocols. This device is equipped with SNMP (Simple Network Management Protocol), which facilitates efficient monitoring and management of network devices. With SNMP, network administrators can keep track of bandwidth usage, device health, and performance metrics, enabling proactive maintenance and troubleshooting.

Additionally, the 3Com 09-1765-001 boasts impressive speed and connectivity options. It features multiple Ethernet ports that support various speeds, typically ranging from 10/100 Mbps, and is designed to provide fast data transfer rates necessary for modern applications. This ensures seamless communication between devices within the network, catering to the increasing demand for speed in data handling, especially in enterprises with heavy usage.

Security is another critical characteristic of the 3Com 09-1765-001. It incorporates essential security features designed to protect sensitive data and ensure safe network access. These features include support for VLANs (Virtual Local Area Networks), access control lists, and port security measures that help to segment network traffic and restrict unauthorized access.

The device is also designed with flexibility in mind, allowing for easy integration into existing network infrastructures. It can function as a standalone device or be easily integrated with other 3Com products, creating a comprehensive networking solution tailored to specific business needs.

In terms of physical characteristics, the 3Com 09-1765-001 is typically housed in a durable chassis designed to endure the rigors of a busy server room or data center. Its compact design also allows for easy rack mounting, optimizing space usage while ensuring efficient operation.

Overall, the 3Com 09-1765-001 represents a combination of advanced features, reliable technology, and user-friendly design, making it an excellent choice for organizations looking to enhance their network capabilities. With its emphasis on speed, security, and manageability, this device is well-suited for the complexities of modern enterprise networking.
Top Page Image Contents