Resolve IP Address Conflicts

To understand what an IP address conflict is, it’s important to first understand what exactly an IP address is. Short for “Internet Protocol address,” an IP address is an identification number given to a specific device on a network. It allows your devices to communicate across the network, allowing for the proper flow of information. Each IP address consists of 32 numbers connected with periods, and each address must be unique within a network to function.

The problem occurs when devices on the same network or subnet are assigned the same static IP address. If this happens, it results in two devices trying to access the same IP address, with neither one able to gain access. Though this access prevention is done to avoid messages going to the wrong host and causing increased confusion, it also hampers network efficiency and temporarily disables operations until the duplicate IP address issue is resolved. This situation is known as an IP address conflict and can be prevented with the appropriate tools.

A standard Windows or Mac operating system will typically display a popup when an IP address conflict has been detected. If you don’t receive a popup, you can use other information to determine whether your device may be in conflict. For instance, your computer will be unable to access the desired network if another device is using your IP address.

Packet loss also indicates a potential address conflict, so you could try to ping your IP address to determine the level of packet loss.

If the above information points to a potential conflict, you should access the router for the relevant subnet. You can inspect the ARP cache for the router to see whether the MAC address for the IP in question changes frequently. Another way to detect an IP address conflict is to use a scanning tool like SolarWinds IP Address Manager.

IP address conflicts are a frequent issue typically resulting from two main causes. One common reason for IP address conflicts is a lapse in DHCP addressing. Your DHCP server will automatically assign unused IP addresses to devices needing them, but it can sometimes make a mistake by thinking dynamic addresses are available simply because their localhost is shut down.

Another common reason for IP address conflict is manual IP assignments can overlap with server assignments. Though DHCP servers automatically assign IP addresses, users can also manually assign them, and when you’re relying on spreadsheets and manual efforts, human error is practically inevitable.

The good news is by knowing the common causes of IP address conflicts, you can take steps to proactively avoid them.

So how do you avoid an IP address conflict? There are a few ways to do so. If you’re looking to continue handling your IP address conflicts on your own without an IP conflict tool, you need to be particularly careful to ensure statically assigned devices are given unique IP addresses. You must also be sure to configure your DHCP servers correctly and ensure they have up-to-date firmware.

However, the best way to avoid IP conflicts is to remove human error from the IP address assignment process. With SolarWinds IPAM, you can automate the IP address scanning process. IPAM can record and report on IP use data for static and dynamic addresses alike. It’s built to use Internet Control Message Protocol (ICMP) or Simple Network Management Protocol (SNMP) to scan and poll your network to help ensure your records are always up-to-date and you won’t accidentally duplicate IP addresses due to human error.

Once you determine the cause of your IP address conflict, you can move forward with fixing it.

In the case of an empty port, you must identify whether each of your localhosts is assigned a unique address. If there’s no address assigned to a host, you can manually assign an address from your IP address pool to the unconnected localhost.

If the IP conflict is related to a single address, you can perform a remote port shutdown to disconnect from your system’s current IP address.

When you use IP conflict detection software, fixing these conflicts is even easier. An IP conflict tool can help you do the following:

• Continually monitor your IP address allocation
• Keep an up-to-date inventory of your IP addresses
• Get a centralized, coherent view of your network
• Identify abnormal behavior
• Edit all your IP settings
• Save admin time

Taken together, these features can help you avoid IP conflicts in the first place and get to the bottom of any conflicts quickly—often before they have a significant impact on the network.

A comprehensive IP address conflict tool is designed to prevent, detect, troubleshoot, and fix IP address conflicts.

• Preventing IP address conflicts is possible with an IP address conflict tool due to proactive IP resource alerts and address tracking tools.
• Detecting IP address conflicts can be quicker when you use an IP address conflict tool. IP monitors are designed to provide real-time alerts the moment a conflict is detected.
• Troubleshooting address conflicts can be easier using IP address conflict software. As soon as you receive a conflict alert, the tool can offer a specific breakdown of potential causes.
• Fixing conflicts can also be easier using an IP address conflict tool like SolarWinds IP Address Manager.

IP conflicts occur when multiple devices have the same IP address. There are several different scenarios in which this can occur—in some cases, it can happen even if you’re using an IP scanner. The scenarios fall under three main categories: static and static, static and dynamic, or dynamic and dynamic.

Static and Static

• SNMP vs. SNMP Neighbor: There’s a conflict between the MAC addresses retrieved from the SNMP OIDs during the subnet scan and from the ARP table of your configured device.
• IPAM Reservation vs. SNMP/SNMP Neighbor: An IP address is reserved under a subnet in your IP scanner containing a MAC address for its internal reference.

Static and Dynamic

• SNMP vs. DHCP: A difference arises between the DHCP leases from a DHCP server and the MAC addresses fetched from an SNMP OID during a subnet scan.
• SNMP Neighbor vs. DHCP: A difference arises between the DHCP leases from a DHCP server and the MAC addresses retrieved from the configured device’s ARP table.
• IPAM Reservation vs. DHCP: A MAC address reserved in your IP scanner for internal reference is then reserved under a subnet.

Dynamic and Dynamic

• DHCP vs. DHCP: This can occur when two DHCP servers are managing a single subnet and there’s a difference between the MAC addresses retrieved from each of the two DHCP servers' lease information.
• DHCP vs. DHCP (Scope Overlap): When part of an IP address range under one DHCP server is also managed by another DHCP server, it’s considered an IP conflict.

The best way to expand IPAM functionalities is by getting the SolarWinds IP Control Bundle, which combines IP Address Manager and SolarWinds User Device Tracker. The bundle delivers integrated endpoint and IP address management to help system administrators and network engineers alike improve network availability and efficiency by eliminating IP address conflicts.

In addition to leveraging the multi-vendor DHCP and DNS management in IPAM, which lets you eliminate configuration errors when provisioning and retiring IP addresses, the IP Control Bundle alerts you as soon as any IP conflicts are detected and empowers you to locate and isolate the relevant device in seconds. Even better, with the IP Control Bundle, you get integrated alerting, monitoring, and historical reporting so you can continuously improve your network reliability.

If you want to expand your IPAM functionalities, you can try the IP Control Bundle free for 30 days and see for yourself how UDT can strengthen your IP conflict resolution capabilities.