Dell PowerSwitch S5212F-ON EMC SmartFabric OS10 User Guide Release 10.5.1 - Page 203

OS10(config-dhcp)# no disable OS10(config-dhcp)# Packet format and options The DHCP server listens on port 67 and transmits to port 68. The DHCP client listens on port 68 and transmits to port 67. In the DHCP packet format, configuration parameters are options in the DHCP packet in type, length, value (TLV) format. To limit the number of parameters that servers 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. The following options are commonly used in DHCP packets. DHCP Option Description Subnet mask Router Domain name server Domain name IP address lease time DHCP message type 1 - Subnet mask of the client 3 - Router IP addresses that serve as the default gateway for the client 6 - Domain name servers (DNS) that are available to the client 15 - Domain name that clients use to resolve hostnames via DNS 51 - Amount of time that the client uses an assigned IP address 53: ● 1 - DHCPDISCOVER ● 2 - DHCPOFFER ● 3 - DHCPREQUEST ● 4 - DHCPDECLINE ● 5 - DHCPACK ● 6 - DHCPNACK ● 7 - DHCPRELEASE ● 8 - DHCPINFORM Parameter request list 55 - A list of parameters that a DHCP client requires from the DHCP server. 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 identifier 60 - User-defined string the Relay Agent uses to forward DHCP client packets to a specific DHCP server DHCP relay agent 82 - Helps secure DHCP traffic that goes through a DHCP relay agent, and ensures that communication information between the DHCP relay agent and the DHCP server is not compromised. option System management 203