Dhcp Auto Logout Overview - Juniper EX3400 Features Manual

DHCP and Other System Services Feature Guide for EX2300, EX3400, and EX4300 Switches
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DHCP Auto Logout Overview

Auto Logout Overview
124
for client IPv4 address assignment. The option 82 matching must also be included in the
address-assignment pool configuration.
[edit system services]
dhcp-local-server {
group group_one {
interface fe-0/0/2.0;
interface fe-0/0/2.1;
}
group group_two {
interface fe-0/0/3.0;
interface fe-0/0/3.1;
}
pool-match-order {
external-authority
ip-address-first;
option-82;
}
}
NOTE: The interface type in this topic is just an example. The
type is not supported by EX Series switches.
Extended DHCP Local Server Overview on page 22
Address-Assignment Pools Overview on page 121
This topic provides an introduction to the DHCP auto logout feature and includes the
following sections:
Auto Logout Overview on page 124
How DHCP Identifies and Releases Clients on page 125
Option 60 and Option 82 Requirements on page 126
Auto logout is supported for DHCP local server and DHCP relay agent. It improves the
efficiency of DHCP IP address assignment by allowing IP addresses to be immediately
released and returned to the address pool when DHCP clients are no longer using the
addresses. DHCP can then assign the addresses to other clients. Without auto logout,
an IP address is blocked for the entire lease period, and DHCP must wait until the address
lease time expires before reusing the address.
Auto logout is particularly useful when DHCP uses long lease times for IP address
assignments and to help avoid allocating duplicate IP addresses for a single client.
For example, you might have an environment that includes set-top boxes (STB) that are
often upgraded or replaced. Each time a STB is changed, the new STB repeats the DHCP
fe- interface
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