 method is also an open management protocol (e.g., SNMP/UDP/IP/AAL) over a specific VPI/VCI value (or a completely separate communications method) allocated to support the general management applications. The peer entity in an ATM device that communicates directly with an NMS is a management agent, not a UME; however, since the management agent can access the MIB instance for the ATM device, it can access all of the UNI ILMI MIB structure instances. The Simple Network Management Protocol (SNMP) without UDP and IP addressing along with ATM UNI management information base (MIB) were chosen for the ILMI. 21.10.1 Interim Local Management Interface (ILMI) Functions An ILMI supports bi-directional exchange of management information between UNI man- agement entities (UMEs) related to UNI ATM layer and physical layer parameters. The communication across the ILMI is protocol symmetric. In addition, each of the adjacent UMEs supporting ILMI will contain an agent application and may contain a management application. Unless stated otherwise for specific portions of the MIB, both of the adjacent UMEs contain the same management information base (MIB). However, semantics of some MIB objects may be interpreted differently. As shown in Figure 21.16, an example list of the equipment that will use the ATM UNI ILMI include: Higher-layer switches such as Internet routers, frame relay switches, or LAN bridges that transfer their frames within ATM cells and forward the cells across an ATM UNI to an ATM switch. Workstations and computers with ATM interfaces that send their data in ATM cells across an ATM UNI to an ATM switch. NETWORK MANAGEMENT Customer Premises Ethernet Token Private Network ATM Switch Customer Premises Public Network ATM Switch Ethernet Public Network ATM Switch Network Public Network ATM Switch Customer Premises Private network ATM Switch Figure 21.16 Examples of equipment implementing the ATM UNI ILMI. (From ATM Forum, Figure 4-2, page 109, Ref. 7.) ATM network switches that send ATM cells across an ATM UNI to othe