(BQ) Part 2 book "Mobile communications" has contents: Mobile network layer, mobile transport layer, support for mobility, outlook, the architecture of future networks, references, wireless application protocol. | 09Chap08 8804 (303-350) 30/5/03 11:05 am Page 303 Mobile network layer 8 his chapter introduces protocols and mechanisms developed for the network layer to support mobility. The most prominent example is Mobile IP, discussed in the first section, which adds mobility support to the internet network layer protocol IP. While systems like GSM have been designed with mobility in mind, the internet started at a time when no one had thought of mobile computers. Today’s internet lacks any mechanisms to support users traveling around the world. IP is the common base for thousands of applications and runs over dozens of different networks. This is the reason for supporting mobility at the IP layer; mobile phone systems, for example, cannot offer this type of mobility for heterogeneous networks. To merge the world of mobile phones with the internet and to support mobility in the small more efficiently, so-called micro mobility protocols have been developed. Another kind of mobility, portability of equipment, is supported by the dynamic host configuration protocol (DHCP) presented in section . In former times, computers did not often change their location. Today, due to laptops or notebooks, students show up at a university with their computers, and want to plug them in or use wireless access. A network administrator does not want to configure dozens of computers every day or hand out lists of valid IP addresses, DNS servers, subnet prefixes, default routers etc. DHCP sets in at this point to support automatic configuration of computers. The chapter concludes with a look at ad-hoc networks in combination with the network layer. This is a fast-growing field of research with standards that are unclear as yet. How can routing be done in a dynamic network with permanent changes in connectivity? What if there are no dedicated routers or databases telling us where a node currently is? The last section deals with some approaches offering routing by extending standard algorithms .
