possible per-hop behaviors. These 64 are divided into networks do not have a strictly reversible mapping. three sets: xxxxx0 for (future) standardization; xxxx01 and xxxx11 for experimental or local use. Not all values may be supported by all the networks, and it may be Manageability necessary to map the PHB values from one network to On a converged network, to have a seamless performance another to obtain a relatively consistent behavior. Until it is crucial to manage your network carefully and XXXXXX, where X is 0 or 1 for a total of 64 codepoints DSCP serves as a table index to loop up a Per Hop Behavior Standard DS Codepoints will be registered RFC2474 (6 bits) DS field (8 bits) IPv4 Frame Structure Figure 3.2-11 Differentiated services bits. CHAPTER 3.2 Network infrastructure efficiently manage your limited bandwidth, particularly Clocks at the sender and the receiver are not synchro- for real-time applications such as voice packets over the nized; hence, the receiver may play out audio slightly network. One of the options to manage your network in faster than it was generated (thereby sometimes running an efficient manner is a policy-based management tool out of audio to play) or slightly slower (thereby falling with a real-time voice/data monitoring tool. Usually an further and further behind the source). excellent class policy based with real-time voice/data and To make matters worse, individual packets of audio converged network management system supports con- may experience more or less delay as they travel through figuring the network in accordance with business needs the network. This causes variations in the inter-arrival and requirements. Most network vendors offer or sup- time. Some packets may experience "infinite delay" (be port PC/Windows applications that provide a means to lost) or such long delay that they become useless or stale. express business policies in terms of rules that govern the The main technique for dealing with variable propagation behavior of the network. These rules may, in tu