 the routing trajectory becomes progressively more indirect. 17.9.3 IP Protocol and Signalling Overheads At protocol level, the overheads of SS7 have been, or are being, replaced by the 'lighter signalling load' of the TCP/IP or UDP protocol stack working with traffic shaping and IP prioritisation protocols (MPLS, Diffserv, RSVP, etc.). Any efficiency gain achievable is directly dependent on the offered traffic mix. If a significant percentage of offered traffic is real time/conversational, the assumption of an efficiency gain from IP signalling and traffic shaping is invalid. If average packet lengths are 1500 bytes or so, IPV4 or IPV6 address overheads are relatively trivial. However, if a significant percentage of traffic is multimedia and time-sensitive or time- interdependent, IP packet traffic (IP voice, IP audio, IP video) will be mapped on to fixed and short (typically 92 bytes or less) fixed-length packets and IP address overhead will be substantial. In radio systems, this can be equivalent to taking between 4 and 5 dB of link budget out of the radio system. Given that one dB of link budget (rather approximately) equates to 10% increase in network density then it is clear that IP addressing and signalling overhead adds directly to the dollardensity costs of deploying a wireless network. Similarly, a multimedia multiplex will require fixed length packets in order to preserve the time-domain properties of Network Software - The User Experience the multiplex. The flexibility of variable-length packets (one of the claimed advantages of IP when compared to ATM) therefore no longer applies. 17.9.4 Connectionless is Better than Connection Orientated? The always-on connectivity implicit in a packet network delivers efficiency benefits when handling small bursts of data. In a GSM network, the 1 to 2 seconds of setup delay in a circuit switched call (or 3 to 4 seconds in a Release 99 network) represents a major overhead when handling short bursts of data. However, these packet efficiency benefits are only valid wi