What Is Static IP Assignment in RADIUS?

In broadband and ISP networks, static IP assignment means giving a specific, fixed IP address to a subscriber every time they connect — regardless of when or how they log in. Unlike dynamic IP allocation (handled by DHCP or IP pools), static IPs are tied to a user account and remain consistent across sessions.

For ISPs managing enterprise clients, leased line customers, VPN users, or any subscriber who needs a permanent public IP, configuring static IP assignment through RADIUS is the most scalable and reliable approach.

OneRADIUS, the AAA RADIUS server software by ARCR Technologies, makes static IP assignment straightforward using standard RADIUS reply attributes — no complex scripting or external tools required.

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Why Use RADIUS for Static IP Assignment?

Using RADIUS to manage static IPs gives ISPs a centralised, policy-driven control plane. Here is why it matters:

  • **Centralised management** — All IP assignments are stored in the RADIUS database, not scattered across routers or DHCP servers
  • **Per-user granularity** — Each subscriber can have their own dedicated IP without touching NAS or router configs
  • **Audit and accountability** — Every session is logged with the assigned IP, making troubleshooting and compliance easier
  • **Scalability** — Works seamlessly whether you manage 100 or 100,000 subscribers
  • **Protocol support** — Works with PPPoE, IPoE, L2TP, and other access technologies
💡 Static IP via RADIUS is especially important for business broadband customers who need consistent IPs for hosting servers, remote access VPNs, or firewall whitelisting.

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Key RADIUS Attributes Used for Static IP Assignment

RADIUS uses reply attributes sent in the Access-Accept packet to instruct the NAS (Network Access Server) how to handle a session. For static IP assignment, the relevant attributes are:

Framed-IP-Address (Attribute 8)

This is the primary attribute used to assign a specific IP address to a subscriber.

  • **Attribute ID:** 8
  • **Type:** IP Address
  • **Direction:** Sent by RADIUS server to NAS in Access-Accept
  • **Example Value:** 203.0.113.45

When the NAS receives this attribute, it assigns that exact IP to the PPP or IPoE session of the subscriber.

Framed-IP-Netmask (Attribute 9)

Used along with Framed-IP-Address to define the subnet mask for the assigned IP.

  • **Attribute ID:** 9
  • **Type:** IP Address (mask format)
  • **Example Value:** 255.255.255.0

Framed-Route (Attribute 22)

Used when you need to push a static route to the NAS for routing traffic to the subscriber IP or subnet.

  • **Attribute ID:** 22
  • **Type:** String
  • **Example Value:** 203.0.113.45/32 0.0.0.0 1
💡 Framed-Route is optional for simple static IP setups but useful when the subscriber IP belongs to a different subnet or when routing specific prefixes through the session.

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Prerequisites Before You Begin

Before configuring static IP assignment in OneRADIUS, make sure the following are in place:

  • **OneRADIUS is installed and running** on your server (Ubuntu/CentOS or Windows Server)
  • **NAS device is configured** as a RADIUS client in OneRADIUS (MikroTik, Cisco, Juniper, Huawei, etc.)
  • **The static IP address** you want to assign is part of your allocated IP pool and not used by any other subscriber or device
  • **Database access** to OneRADIUS (MySQL/MariaDB backend)
  • **Test PPPoE or IPoE credentials** for verification
⚠️ Never assign an IP that is already in use by another session or device. Always verify the IP is free before assigning it to a subscriber account.

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Step-by-Step: Configure Static IP Assignment in OneRADIUS

Step 1 — Log In to OneRADIUS Admin Panel

Open your browser and navigate to your OneRADIUS dashboard. Log in with your admin credentials.

From the main menu, go to Subscribers or User Management depending on your OneRADIUS version.

Step 2 — Select or Create the Subscriber Account

  • To configure for an existing user: search by username or phone number and open the subscriber profile
  • To configure for a new user: click **Add Subscriber** and fill in the required details (username, password, plan, etc.)

Once you are on the subscriber profile page, look for the RADIUS Attributes or Reply Attributes section.

Step 3 — Add the Framed-IP-Address Attribute

In the Reply Attributes section:

  • Click **Add Attribute**
  • Select **Framed-IP-Address** from the attribute dropdown
  • Set the **Operator** to = (equals)
  • Enter the static IP address in the **Value** field — for example: 203.0.113.45
  • Click **Save**
💡 In FreeRADIUS-compatible databases (which OneRADIUS uses), this is stored in the radreply table as: username | Framed-IP-Address | = | 203.0.113.45

Step 4 — (Optional) Add Framed-IP-Netmask

If your NAS or access technology requires an explicit subnet mask:

  • Click **Add Attribute** again
  • Select **Framed-IP-Netmask**
  • Set Operator to =
  • Enter the subnet mask — for example: 255.255.255.255 for a host route or 255.255.255.0 for a /24
  • Click **Save**

Step 5 — (Optional) Add Framed-Route for Static Routing

If the static IP needs to be routed via the session:

  • Add attribute **Framed-Route**
  • Value format: [IP/prefix] [gateway] [metric] — Example: 203.0.113.45/32 0.0.0.0 1
  • Click **Save**

Step 6 — Verify the Configuration in the Database

If you want to verify directly in the database, run the following SQL query against your OneRADIUS database:

SELECT * FROM radreply WHERE username = 'your_subscriber_username';

You should see rows for Framed-IP-Address (and optionally Framed-IP-Netmask and Framed-Route) with the correct values.

⚠️ If you see duplicate entries for Framed-IP-Address in radreply, the NAS behaviour may be unpredictable. Delete duplicates and keep only one entry per attribute per user.

Step 7 — Test the Static IP Assignment

  • Have the subscriber disconnect and reconnect (for PPPoE, drop and re-dial the connection)
  • On the NAS side, check the active session: on MikroTik use '/ppp active print', on Cisco use 'show subscriber session'
  • Confirm the IP shown in the session matches the IP you configured in OneRADIUS
  • Check the **Accounting Logs** in OneRADIUS — the Framed-IP-Address field in the accounting record should reflect the static IP
💡 You can also use the OneRADIUS live session monitor to verify the assigned IP without logging into the NAS.

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Configuring Static IP via SQL Directly (Advanced)

For bulk operations or scripted provisioning, you can insert static IP assignments directly into the OneRADIUS database:

INSERT INTO radreply (username, attribute, op, value)

VALUES ('subscriber_username', 'Framed-IP-Address', '=', '203.0.113.45');

For multiple users, you can batch-insert from a CSV using a simple script or MySQL LOAD DATA INFILE command.

⚠️ Always take a database backup before running bulk SQL operations. A wrong INSERT can affect authentication for many subscribers.

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Static IP Assignment for Different Access Technologies

PPPoE (Point-to-Point Protocol over Ethernet)

Most common in Indian ISP networks. The Framed-IP-Address attribute in the Access-Accept packet is automatically applied to the PPP interface. Works with MikroTik, Cisco, Huawei MA5600, and most other NAS platforms.

IPoE (IP over Ethernet / DHCP-based)

For IPoE, the NAS intercepts DHCP requests and sends a RADIUS Access-Request. OneRADIUS replies with Framed-IP-Address, and the NAS instructs the DHCP server or its own DHCP pool to assign that specific IP to the subscriber.

💡 For IPoE static IP to work, your NAS must support RADIUS-controlled DHCP assignment. Verify this capability with your NAS vendor documentation.

L2TP (Layer 2 Tunneling Protocol)

For L2TP wholesale or retail setups, static IP via Framed-IP-Address works the same way. The LNS (L2TP Network Server) applies the IP from the RADIUS reply to the virtual PPP interface inside the tunnel.

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Common Issues and Troubleshooting

Issue 1 — Subscriber Still Gets a Dynamic IP

Possible causes:

  • Framed-IP-Address not saved correctly in radreply
  • NAS is using a local IP pool override
  • RADIUS reply is not being received by NAS (check RADIUS logs)

Fix: Check radreply table, verify NAS RADIUS config, review OneRADIUS debug logs.

Issue 2 — IP Address Conflict

Possible causes:

  • The static IP is also part of a dynamic pool on the NAS
  • Another subscriber has the same IP assigned

Fix: Remove the IP from the NAS dynamic pool, search radreply for duplicate IP entries.

Issue 3 — Authentication Fails After Adding Static IP

Possible causes:

  • Syntax error in radreply attribute (wrong operator or value format)
  • Conflicting attributes in radcheck or radgroupreply tables

Fix: Use the OneRADIUS test authentication tool to simulate login and inspect the full Access-Accept packet.

⚠️ Always test static IP configuration in a staging or test subscriber account before rolling it out to live customers.

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Best Practices for Static IP Management in OneRADIUS

  • **Maintain an IP address register** — Keep a spreadsheet or use OneRADIUS subscriber notes to track which IP is assigned to which customer
  • **Use /32 host routes** — Always assign static IPs as host routes (/32) to avoid routing conflicts
  • **Document the NAS pool exclusion** — Remove static IPs from dynamic pools on all NAS devices to prevent conflicts
  • **Monitor IP usage** — Use OneRADIUS accounting reports to verify that static IPs are being used as expected
  • **Automate provisioning** — Integrate static IP assignment with your OSS/BSS system via OneRADIUS API for zero-touch provisioning
  • **Review regularly** — Periodically audit your radreply table to reclaim IPs from decommissioned accounts

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Why OneRADIUS Makes Static IP Management Easy

OneRADIUS by ARCR Technologies is purpose-built for Indian ISPs — supporting BSNL last-mile, fiber broadband, wireless ISPs, and enterprise broadband providers. Its admin panel provides a clean interface for managing reply attributes per subscriber without requiring deep RADIUS expertise.

Key advantages of using OneRADIUS for static IP management:

  • **GUI-based attribute management** — No need to write SQL for every IP assignment
  • **Bulk import support** — Assign static IPs to hundreds of subscribers via CSV import
  • **Real-time session monitoring** — Instantly verify assigned IPs from the dashboard
  • **API integration** — Connect with billing platforms like WHMCS, Sochitel, or custom OSS via REST API
  • **24/7 support from ARCR Technologies** — Based in Hyderabad, with deep expertise in Indian ISP deployments
💡 Want to see OneRADIUS in action? Visit oneradius.com to request a demo or download the trial version.

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Conclusion

Configuring static IP assignment using RADIUS is a fundamental skill for any ISP network engineer. By leveraging the Framed-IP-Address attribute in RADIUS reply packets, you can assign dedicated, permanent IPs to your subscribers in a centralised, scalable, and auditable way.

With OneRADIUS, the process is simplified through an intuitive admin interface, robust database management, and full compatibility with all major NAS platforms used in Indian ISP networks.

Start managing your static IPs the right way — with OneRADIUS.

Visit oneradius.com to learn more or get started today.