yzes the infor- mation and forwards a decision to the PEP. All the PEP has to do is enforce the decision. An Internet Draft called COPS-MAID introduces QoS extensions for multi- access environments. The main benefits of COPS are that it creates efficient com- munication between policy servers and policy-aware devices, and it increases interoperability among different vendors' systems. LDAP LDAP, a standard directory server technology for the Internet, allows retrieval of information from multivendor directories. More specifically, it is a net- working protocol for querying and modifying directory services running over TCP/IP. LDAP version 3 (LDAPv3) provides client systems, hubs, switches, and routers, as well as a standard interface to rewrite directory information. Equipment and direc- tory vendors use LDAP for accessing and updating directory information. The cur- rent version, LDAPv3, is specified in IETF RFC 3377. QoS and Prevailing Conditions There are quite a few potential approaches to implementing QoS. Which one makes sense often depends on what is available and what the prevailing conditions are. At this point, ATM is used most frequently because it offers the strongest abilities to address traf- fic engineering and resource utilization. Right now, high hopes are also pinned on MPLS because it does a good job of marrying the best qualities of IP with the best qualities of ATM. But once again, we are in an era of many emerging technologies. This chapter should give you an appreciation of how many issues there are to understand in the proper administration of the emerging business-class services that promise to generate large revenues. The MPLS Architecture MPLS was created to address the weaknesses in traditional IP networks. Remem- ber that IP was designed to support best-effort service. Routers do not see rings or connections; they see ports and addresses via the routing tables and proprietary priority cues. IP routing lacks intelligence. Least-cost routing causes traffic to take the shortest number of