1.4 Relationship to Other Protocols
The extension options and messages defined in this document are transported according to the provisions of the DHCP Failover Protocol.
The DHCP Failover Protocol (as specified in [IETF-DHCPFOP-12]) runs over the TCP protocol [RFC793]. TCP is used not only for transporting control and data messages, but also for determining the communication status between the primary and secondary servers.
As explained in [IETF-DHCPFOP-12] section 5, the data messages in the DHCP Failover Protocol exchange information about the DHCP client and the IP address assigned to the client between the DHCP servers configured to be failover peers.
DHCP can be used as one of the enforcement mechanisms defined for Network Access Protection (NAP) as described in [MSDN-NAP]. The vendor-specific options used for DHCP-based enforcement of NAP are defined by the Dynamic Host Configuration Protocol (DHCP) Extensions for Network Access Protection (NAP) ([MS-DHCPN] section 1). These extensions affect the contents of DHCP messages when NAP is used. Similarly, NAP-related information is stored in the DHCP server lease database and has to be synchronized between the two servers. The extensions defined in this document include options for synchronizing NAP information.
The Microsoft Dynamic Host Configuration Protocol (DHCP) Server Management Protocol [MS-DHCPM] affects the contents of failover messages and the behavior of failover peers extended by this protocol by setting or modifying DHCP server configurations. The relationship between the DHCP protocol elements and the shared Abstract Data Model (ADM) elements from the Microsoft Dynamic Host Configuration Protocol (DHCP) Server Management Protocol [MS-DHCPM] (see [MS-DHCPE] section 1.4) also applies to servers that implement DHCP NAP enforcement.
The following diagram illustrates the layering of the protocol described in this document with other protocols in its stack.
Figure 5: Protocol layering diagram
The following data flow diagram illustrates the interaction of the server implementation of this protocol with those of other protocols in its stack.
Figure 6: Server-side interaction with related protocols