DHCP and DHCP Relay in the Junos Environment

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The Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network. In this blog post, we will discuss DHCP and DHCP Relay in the Junos environment, which is a crucial topic for the JNCIS-ENT certification.

DHCP in Junos

In Junos, DHCP is implemented as a client/server model. The DHCP client is typically a desktop or laptop, and the DHCP server is a network device such as a router or switch.

To configure DHCP in Junos, you need to follow these steps:

Define the DHCP pool:

set system services dhcp pool 192.0.2.0/24 address-range low 192.0.2.2 high 192.0.2.254

Set the default gateway:

set system services dhcp pool 192.0.2.0/24 default-lease-time 691200

Set the DNS server:

set system services dhcp pool 192.0.2.0/24 name-server 203.0.113.1

DHCP Relay in Junos

DHCP Relay is a feature that allows a DHCP server to provide IP addresses to clients on subnets other than the one it resides on. The DHCP relay agent receives DHCP requests and forwards them to a DHCP server.

To configure DHCP Relay in Junos, you need to follow these steps:

Enable DHCP relay:

set forwarding-options helpers bootp relay-agent-option

Specify the DHCP server:

set forwarding-options helpers bootp server 203.0.113.1

Specify the interface:

set forwarding-options helpers bootp interface ge-0/0/0.0

In conclusion, understanding DHCP and DHCP Relay in the Junos environment is essential for network engineers preparing for the JNCIS-ENT certification. It allows for efficient IP address management and enables communication between devices on different subnets.