DHCP server support on the 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C is designed to be used for IP address assignment used for local management access to the node or to the devices connected to the node for maintenance activities.
DHCP is a configuration protocol used to communicate network information and configuration parameters from a DHCP server to a DHCP-aware client. DHCP is based on the BOOTP protocol, with additional configuration options and the added capability of allocating dynamic network addresses. DHCP-capable devices are also capable of handling BOOTP messages.
A DHCP client is an IP-capable device (typically a computer or base station) that uses DHCP to obtain configuration parameters such as a network address. A DHCP server is an Internet host or router that returns configuration parameters to DHCP clients. A DHCP/BOOTP Relay agent is a host or router that passes DHCP messages between clients and servers.
Home computers in a residential high-speed Internet application typically use the DHCP protocol to have their IP address assigned by their Internet service provider.
The following is supported on different 7210 SAS platforms:
The 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C platforms can act as a DHCP Relay agent, or a local DHCP server.
The 7210 SAS-K 2F1C2T platform can act as a DHCP relay agent only.
The 7210 SAS-D and 7210 SAS-Dxp platforms can act as a DHCP relay agent only.
The following paragraphs describe the functionality available on 7210 SAS as DHCP server, and as a relay agent.
For DHCP, the DHCP protocol requires the client to transmit a request packet with a destination broadcast address of 255.255.255.255 that is processed by the DHCP server. Because IP routers do not forward broadcast packets, this would suggest that the DHCP client and server must reside on the same network segment. However, for various reasons, it is sometimes impractical to have the server and client reside in the same IP network. When the 7210 is acting as a DHCP Relay agent, it processes these DHCP broadcast packets and relays them to a preconfigured DHCP server. Therefore, DHCP clients and servers do not need to reside on the same network segment.
When the 7210 SAS is acting as a local DHCP server, it processes these DHCP broadcast packets and allocates IP addresses for the DHCP client as needed.