Article Detail

Description

This article describes the issue of a user being randomly assigned an IP address, even though the static binding of IP-MAC in DHCP services has been configured on a J-series or SRX device.

Symptoms

Static bindings provide configuration information for specific clients. This can include one or more fixed Internet addresses, client hostname, and a client identifier.

Assume that you have DHCP static binding between IP-MAC for 10.64.0.41 - 00:21:b7:72:31:63 :

The address 10.64.0.41 IP address will belong to the DHCP pool.

You can check the configuration by referring to the following link:

http://www.juniper.net/techpubs/en_US/junos9.5/information-products/topic-collections/swconfig-system-basics/dhcp-manual-static-address-bindings.html

However, even after verifying the configuration, the client is randomly assigned a MAC address.

To confirm this, run the following command:
```
> show system services dhcp binding
```

Solution

To ensure that the client receives the static address, as per it's MAC, you have to clear the dynamic binding entry:

> clear system services dhcp binding < dynamic address, which is associated with the configured MAC >

After that , connect the client again and you will see it gaining the static (configured) IP address. You can verify this via the following command:

> show system services dhcp binding | match < ip address eg. 10.64.0.41 >