<Li> Management functions, i.e. functions that permit to configure, instantiate, monitor, terminate the communications of two or more entities: there is a specific application - layer protocol, common management information protocol (CMIP) and its corresponding service, common management information service (CMIS), they need to interact with every layer in order to deal with their instances . </Li> <Li> Multiprotocol Label Switching (MPLS) MPLS, ATM, and X. 25 are 3a protocols . OSI divides the Network Layer into 3 roles: 3a) Subnetwork Access, 3b) Subnetwork Dependent Convergence and 3c) Subnetwork Independent Convergence . It was designed to provide a unified data - carrying service for both circuit - based clients and packet - switching clients which provide a datagram - based service model . It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, SONET, and Ethernet frames . Sometimes one sees reference to a Layer 2.5 . This is a fiction create by those who are unfamiliar with the OSI Model and ISO 8648, Internal Organization of the Network Layer in particular . </Li> <Li> ARP determines the mapping of an IPv4 address to the underlying MAC address . This is not a translation function . If it were IPv4 and the MAC address would be at the same layer . The implementation of the MAC protocol decodes the MAC PDU and delivers the User - Data to the IP - layer . Because Ethernet is a multi-access media, a device sending a PDU on an Ethernet segment needs to know what IP address maps to what MAC address . </Li> <Li> DHCP, DHCP assigns IPv4 addresses to new systems joining a network . There is no means to derive or obtain an IPv4 address from an Ethernet address . </Li>

Which of the following is not a layer of the osi model