Connectivity Guide

Conguration parameters are options in the DHCP packet in type, length, value (TLV) format. To limit the number of parameters that
servers must provide, hosts enter the parameters that they require and the server sends only those parameters. DHCP uses the User
Datagram Protocol (UDP) as its transport protocol.
Figure 10. DHCP Packet Format
The table shows common options using DHCP packet formats.
DHCP Option Description
Subnet mask 1 — Subnet mask of the client
Router 3 — Router IP addresses that serve as the default gateway for the client
Domain name server 6 — Domain name servers (DNS) that are available to the client
Domain name 15 — Domain name that clients use to resolve hostnames via DNS
IP address lease time 51 — Amount of time that the client uses an assigned IP address
DHCP message type 53:
• 1 — DHCPDISCOVER
• 2 — DHCPOFFER
• 3 — DHCPREQUEST
• 4 — DHCPDECLINE
• 5 — DHCPACK
• 6 — DHCPNACK
• 7 — DHCPRELEASE
• 8 — DHCPINFORM
Parameter request
list
55 — Parameters the server requires for DHCP clients. This is a series of octets where each octet is a DHCP
option code
Renewal time 58 — Amount of time, after the IP address is granted, that the client attempts to renew its lease with the original
server
Rebinding time 59 — Amount of time, after the IP address is granted, that the client attempts to renew its lease with any server, if
the original server does not respond
Vendor class
identier
60 — User-dened string the Relay Agent uses to forward DHCP client packets to a specic DHCP server
User port stacking 230 — Stacking option variable that provides the DHCP server stack-port details when the DHCP oer is set
End 255 — Signal of the last option in the DHCP packet
System management 583