DHCP message
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... described in Section 4.1.
c. DHCP messages are sent back and forth between the remote host and
the DHCPv4 server ...
... Optional parameters field.
Table 1: Description of fields in the DHCP message
The htype value is set to the value 31, signifying a virtual IPsec
tunnel mode ...
... stateless, the security gateway SHOULD insert
appropriate information in the DHCP message prior to forwarding to
one or more DHCP servers. This enables the security gateway ...
... messages will use the newly established VPN SA. Similarly, all DHCP
messages subsequently sent by the DHCPv4 server will be forwarded by
the security gateway ...