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[EX/QFX] DHCP server exclude addresses on Junos ELS devices

  [KB31670] Show Article Properties


Summary:

This article explains how to exclude IP addresses from an IP pool on ELS devices.

Symptoms:

In some scenarios, network administrators may need to exclude certain IP address from a DHCP pool. In ELS devices, the exclude keyword was removed, hence the exclusions of addresses is not as intuitive as in a legacy configuration.

Cause:

The exclude keyword was removed from ELS configuration options.

Solution:

The achieve the exclude functionality, you have the following options:

Creating static bindings:

set access address-assignment pool vlan200-pool family inet host butterc up ip-address 192.168.25.10 hardware-address 00:00:00:00:aa:00
set access address-assignment pool vlan200-pool family inet host butterc up1 ip-address 192.168.25.11 hardware-address 00:00:00:00:aa:01
set access address-assignment pool vlan200-pool family inet host butterc up2 ip-address 192.168.25.230 hardware-address 00:00:00:00:aa:02
set access address-assignment pool vlan200-pool family inet host butterc up3 ip-address 192.168.25.231 hardware-address 00:00:00:00:aa:03


Any addresses configured with a static binding won’t be assigned by DHCP

Curly bracket format:
> show configuration access
address-assignment {
    pool vlan200-pool {
        family inet {
            network 192.168.20.0/24;
            host butterc {
                hardware-address 00:00:00:00:aa:00;
                ip-address 192.168.20.10;
            }
        }
    }
}
 

Creating ranges:

Define a range of addresses in the address-assignment pool. The range is a subset of addresses within the pool that can be assigned to clients. If no range is specified, then all addresses within the pool are available for assignment. Configure the name of the range and the lower and upper boundaries of the addresses in the range:

[edit]
user@switch# set access address-assignment pool pool-name family family range range-name low low-IP-address
user@switch# set access address-assignment pool pool-name family family range range-name high high-IP-address

For example:

[edit]
user@switch# set access address-assignment pool pool1 family inet range range1 low 198.51.100.3
user@switch# set access address-assignment pool pool1 family inet range range1 high 198.51.100.15
user@switch# set access address-assignment pool pool1 family inet range range2 low 198.51.100.30
user@switch# set access address-assignment pool pool1 family inet range range2 high 198.51.100.40
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