Dhcp Address Allocation Support Of Wan Interfaces - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide
Note:
For the configurations specifying to add sub-option 2, sub-option 3, and sub-option 4 in
the response packets to take effect, you must configure the DHCP server to add
sub-option 1.
II. Operational mechanism of using option 184 on DHCP server
The DHCP server encapsulates the information for option 184 to carry in the response
packets sent to the DHCP clients. Supposing that the DHCP clients are on the same
segment as the DHCP server, the operational mechanism of option 184 support on
DHCP server is as follows:
1) A DHCP client sends to the DHCP server a request packet carrying option 55,
which indicates the client requests the configuration parameters of option 184.
2) The DHCP server checks the request list in option 55 carried by the request
packet, and then adds the sub-options of option 184 in the Options field of the
response packet sent to the DHCP client.
Note:
Only when the DHCP client specifies in option 55 of the request packet that it requires
option 184, does the DHCP server add option 184 in the response packet sent to the
client.

9.2.7 DHCP Address Allocation Support of WAN Interfaces

The traditional DHCP client function can only be implemented on Ethernet interfaces,
while all the current functions of DHCP server, DHCP relay, and DHCP client can be
implemented on WAN interfaces encapsulating PPP, HDLC, or FR. The DHCP-enabled
WAN interfaces include synchronous/asynchronous serial interface and E1 interface.
The following describes the operational procedure of the DHCP server and DHCP
client based on the encapsulated link layer protocol.
I. Enabling DHCP address allocation on a WAN interface encapsulating PPP
With PPP encapsulated and DHCP enabled, an interface starts with PPP negotiation,
and after achieving negotiation success, performs DHCP packet interaction. The
following lists the detailed procedure:
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Chapter 9 DHCP Configuration