e asymmetries in service as well. Why is my computer getting SO slow when downloading files from the Internet? The origin of the problem could be located either in the PC, the corresponding inter- working modems, the copper, cable modem or wireless access network, the ISP and finally in the different nodes on the Internet network. Its determination will not be a simple man- agement task, particularly considering that many operators are involved in the Internet communication and that they may have a null or at least very limited cooperation among their management systems. 1. The ITU-T (telecommunication network management - TMN) and the IETF (sim- ple network management protocol - SNMP) approaches on network management, although based on similar principles, finally became pretty different (different pro- tocols, different managed objects definitions, different terminology, etc.). Understanding Changing Telecommunications - Building a Successful Telecom Business 2. Usually isolated management systems already exist, either for particular layers, group of vendor's equipment or vendor's networks, or any combination of them. 3. Some vendors' equipment and networks, particularly old legacy networks, use propri- etary management systems not based on the manager-agent principle. 4. Configuration management is frequently addressed by other means such as Telnet, proprietary CLI, FTP/FTAM for bulk transfer, and DHCP and LDAP in cases related to server or server-based configuration. Examples of layered interworking: see Chapter 12, for example Figure 12.12 and Chapter 3, Figure 3.32. Layering of technologies may correspond to a layering of actors, but also a single actor might have integration problems, originated from the list above. The GMPLS standard in chapter 12 is interesting since it integrates many layers. Examples of 'vertical' interworking: see Chapter 15. Possible Solution A solution to possible problems is the use of mediation functions, called 'mediation devices' in TMN and 'proxy agents' in the Internet. The med