Impact of Two Wireless Access Points with the Same SSID

With the increasing use of wireless networks, it's important to understand how they operate and any potential issues they may face. One frequent concern is what happens when two wireless access points (APs) have the same SSID. This article aims to demystify the impact of this scenario, offering insights that can help mitigate potential issues.

Understanding SSIDs and Wireless Access Points

Before diving into potential issues, it's crucial to clarify some terminology:

SSID (Service Set Identifier): This is the name used to identify a wireless network. It is visible to nearby devices unless hidden. Wireless Access Points (APs): These are devices that allow wireless devices to connect to a wired network.

When Two APs Have the Same SSID

The behavior when two APs with the same SSID are present depends on several factors, including their physical proximity and the configuration of the devices attempting to connect.

Scenario 1: Distant APs

If the two APs are far apart and do not interfere with each other, they will both function normally. Wi-Fi devices can connect to either without issue, and there will be no conflict.

Scenario 2: Close and Interfering APs

When two APs are close to each other and interfere with each other, issues can arise. This is common in densely crowded areas such as public places, hotels, and airports. The following scenarios can occur:

Seamless Roaming

When the APs are synced and configured with the same SSID and password, it's possible to roam between them seamlessly. This can be convenient if you have one AP serving as a gateway for the network. However, there are caveats including:

Network Congestion: If both APs are connected directly to the internet, roaming can cause a disruption in connectivity. You might lose your internet connection and be assigned a new IP and route to the internet. Session Loss: When you roam, your active sessions may be interrupted, requiring you to restart applications.

Separate Channels and MAC Addresses

Most modern APs automatically choose to operate on different channels to minimize interference. Additionally, each AP has a unique MAC address, ensuring that devices can distinguish between them.

Real-World Examples

One relatable example is the public Wi-Fi in places like hotels and restaurants. McDonald's, for instance, often provides Wi-Fi access with a public SSID. The device will connect to the strongest signal, and often, the same SSID will be used across multiple locations. This is why, as you move to a different McDonald's, your device will typically connect to the McDonald's network, even if you are in a different store.

Another scenario is when both APs have the same SSID but different passwords. In this case, devices will connect to the one with the strongest signal, and a conflict is less likely to occur.

Understanding Battle of the Stars

In wireless networking, if multiple APs with the same SSID are present, it can create a phenomenon known as a “battle of the stars”. This occurs when a device has to choose between multiple access points with the same SSID, leading to potential performance issues and connectivity problems.

Mitigating the Impact of SSID Collisions

To avoid the complexities and potential connectivity issues caused by SSIDs with the same label, it's best to:

Unique SSIDs: Ensure each AP has a unique SSID, even if they share other configurations. Proximity Management: Place APs in such a way to minimize their physical proximity to each other and avoid interference. Network Segmentation: Implement a network segmentation strategy to prevent direct internet access from multiple APs, reducing the risk of roaming disruptions.

By implementing these strategies, you can ensure a smoother and more reliable Wi-Fi experience for your guests or employees.

Conclusion

While having two or more APs with the same SSID can lead to multiple issues, with proper configuration and planning, the setup can be managed effectively. Understanding the terms, scenarios, and potential solutions will help you maintain a stable and seamless wireless network environment.