Amer Networks E5Web GUI - Manual (Page 359)

Chapter 5: DHCP Services
This chapter describes DHCP services in cOS Core.
• Overview, page 359
• cOS Core DHCP Servers, page 361
• IPv4 DHCP Relay, page 368
• IP Pools, page 371
• DHCPv6 Servers, page 374
5.1. Overview
Dynamic Host Configuration Protocol (DHCP) is a protocol that allows network administrators to
automatically assign IP numbers to computers on a network. It can perform this function both for
IPv4 and IPv6 addresses.
IP Address Assignment
A DHCP Server implements the task of assigning IP addresses to DHCP clients. These addresses
come from a predefined IP address pool which DHCP manages. When a DHCP server receives a
request from a DHCP client, it returns the configuration parameters (such as an IP address, a MAC
address, a domain name, and a lease for the IP address) to the client in a unicast message.
DHCP Leases
Compared to static assignment, where the client owns the address, dynamic addressing by a
DHCP server leases the address to each client for a predefined period of time. During the lifetime
of a lease, the client has permission to keep the assigned address and is guaranteed to have no
address collision with other clients.
Lease Expiration
Before the expiration of the lease, the client needs to renew the lease from the server so it can
keep using the assigned IP address. The client may also decide at any time that it no longer
wishes to use the IP address it was assigned, and may terminate the lease and release the IP
address.
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