We consider the problem of providing network access to hosts whose physical location changes with time. Such hosts cannot depend on traditional forms of network connectivity and routing because their location, and hence the route to reach them, cannot be deduced from their network address. In this paper, we explore the concept of providing continuous network access to mobile computers, and present a set of IP-based protocols that achieve that goal. They are primarily targeted at supporting a campus environment with mobile computers, but also extend gracefully to accommodate hosts moving between different networks. The key feature is the dependence on ancillary machines, the Mobile Support Stations (MSSs), to track the location of the Mobile Hosts. Using a combination of caching, forwarding pointers, and timeouts, a minimal amount of state is kept in each MSS. The state information is kept in a distributed fashion; the system scales well, reacts quickly to changing topologies, and does ...

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Abstract- Host mobility is becoming an important issue due to the recent proliferation of notebook and palmtop computers, the development of wireless network interfaces, and the growth in global internetworking. This paper describes the design and implementation of a mobile host protocol, called the Internet Mobile Host Protocol (IMHP), that is compatible with the TCPDP protocol suite, and allows a mobile host to move around the Inter-net without changing its identity. In particular, IMHP provides host mobility over both the local and wide area, while remaining transparent to the user and to other hosts communicating with the mobile host. IMHP features route optimization and integrated authentication of all management packets. Route optimization allows a node to cache the location of a mobile host and to send future packets directly to that mobile host. By authenticating all management packets, IMHP guards against possible attacks on packet routing to mobile hosts, including the interception or redirection of arbitrary packets within the network. A simple new authentication mechanism is introduced that preserves the level of security found in the Internet today, while accommodating the transition to stronger authentication based on public key cryptog-raphy or shared keys that may either be manually administered or provided by a future Internet key management protocol. I.

Abstract new address must be edited into various configuration ” files. This paper describes a new protocol for transparently rout-ing packets to mobile hosts operating in a large internet-work. The protocol, called the Mobile Host Routing Proto-col (MHRP), allows any host to become mobile at any time, yet there is no penalty for a host being “mobile capable,” since the protocol automatically uses only the standard in-ternetwork routing mechanisms and adds no overhead when a mobile host is currently connected to its home network. The paper concentrates on the design of MHRP as it ap-plies to the Internet using IP. Mobile hosts use only their “home ’ ’ IP addresses, regardless of their current location in the Internet. No changes are required in stationary hosts that communicate with mobile hosts, and no changes are required in mobile hosts above the IP level. MHRP intro-duces several new features to provide better robustness for routing to mobile hosts, and provides better scalability to very large numbers of mobile hosts than previous mobile host protocols. 1.

With rapid technological advances being made in the area of wireless communications it is expected that, in the near future, mobile users will be able to access a wide variety of services that will be made available over future high-speed networks. The quality of these services in the high-speed network domain can be specified in terms of several QOS parameters. In this paper we identify two new QOS parameters unique to the mobile environment -- guarantee of seamless service and ensuring graceful degradation of service in situations where user demands exceed the network's capacity to satisfy them. A network architecture and a suite of transport level services are proposed that enables these QOS parameters to be satisfied. To appear in J. Computer Communications 1 Introduction Mobile computing refers to an emerging new computing environment incorporating both wireless and wired high-speed networking technologies. In the near future, it is expected that millions of users equipped wit...

Miniaturization and increasing portability of computers will require users in the future to access the network regardless of location. In such an environment, host migration transparency will be an essential feature of wide area networks. In order to achieve host migration transparency, we introduced the concept of virtual network and the propagating cache method [7]. As an example of a virtual network protocol, we also proposed Virtual Internet Protocol (VIP). This paper describes the details of the design and implementation of VIP. We implement VIP by modifying a 4.3BSD-based operating system kernel. This paper also compares the overhead of VIP to that of IP. Measured results indicate that VIP can achieve host migration transparency in the Internet with negligible overhead. 1 Introduction The last several years have brought a dramatic increase in network ubiquity. At the same time, computers continuously increase in power and compactness. In such an environment, a user will want to ...

This paper considers the problem of providing transparent support for very large numbers of mobile hosts within a large internetwork such as the Internet. The availability of powerful mobile computing devices and wireless networking products and services is increasing dramatically, but internetworking protocols such as IP used in the Internet do not currently support host movement. To address this need, the Internet Engineering Task Force (IETF) is currently developing protocols for mobile hosts in the Internet. This paper analyzes the problem to be solved, reviews the current state of that effort, and discusses its scalability to very large numbers of mobile hosts in a large internetwork. 1.

"Mobile Computing" has been a buzzword in the area of computer communications. A technology vital to mobile computing is how to communicate with mobile hosts. This paper proposes a protocol, Virtual Internet Protocol (VIP), that allows hosts to move transparently within the Internet. VIP is defined as an instance of the virtual network protocol, the general protocol supporting mobile hosts. The virtual network protocol is based on the concept of a virtual network and the propagating cache method. VIP is scalable to the total number of mobile hosts and the scale of the Internet, is free from routing loops, and tolerant of loss of control packets. VIP is currently running on operating systems based on 4.3BSD UNIX. The VIP overhead is negligible when compared with IP.

Increasing portability of computers will require users in the future to access the network regardless of location. Host migration transparency will be an essential feature of wide area network environments. We proposed the concept of virtual network and the propagating cache method to achieve host migration transparency [12]. We also established the feasibility of Virtual Internet Protocol (VIP), derived from Internet Protocol (IP), as an example of a virtual network protocol. In this paper, we define VIP in detail and describe how VIP achieves host migration transparency in IP networks. We also show two VIP implementation approaches: 1) VIP as a sublayer; and 2) VIP as an IP option. By modifying an operating systems kernel in each case, we implement VIP using both approaches. We then compare both implementations in terms of overhead, backward compatibility, and other metrics. The measured performance indicates that VIP can provide host migration transparency in IP networks with negli...

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