The guiding principles in the design of IP network management were simplicity and no centralized control. The best effort service paradigm was a result of the original management principles and the other way around. New methods to distinguish the service given to one set of packets or flows relative to another are well underway. However, as IP networks evolve the management approach of the past may not apply to the Quality of Service (QoS)-capable network envisioned by some for the future. This document examines some of the areas of impact that QoS is likely to have on management and look at some questions that remain to be addressed.

Many of the support functions necessary to exploit the mechanisms by which differing levels of service can be provided are limited in scope and a complete framework is non-existent. Various efforts at such a framework have received a great deal of attention and represent a historical shift in scope for many of the organizations looking to address this problem. The purpose of this document is to explore the problems of defining a Service management framework and to examine some of the issues that still need to be resolved.

In recent years the capacity of mainframeclass servers has grown, and the quantity of data they are required to handle has grown with them. As a result, the existing S/390 ® I/O architecture required modifications to support an order of magnitude increase in the bandwidth. In addition, new Internet applications increased the demand for improved latency. Adapters were needed to support more users and a larger number of connections to consolidate the external network interfaces. The combination of all of the above requirements presented a unique challenge to server I/O subsystems. With the introduction of the zSeries TM comes an enhanced version of a new I/O architecture for the mainframe called queued direct I/O (QDIO). The architecture was initially exploited for Gigabit and Fast Ethernet adapters. More recently the architecture was exploited by the OSA-Express network adapter for Asynchronous Transfer Mode (ATM) and highspeed Token Ring connections, and it was exploited by HiperSockets for internal LPARto-LPAR connections. In each of these features, the TCP/IP stack is changed to tightly integrate the new I/O interface and to offload key TCP/IP functions to hardware facilities. For external communications, the offloaded functions are performed by the OSA-Express hardware microcode; for internal communications, the offloaded functions are performed in the zSeries Licensed Internal Code (LIC). The result is a significant improvement in both latency and bandwidth for sockets-based messaging which is transparent to the exploiting applications.