A Proposed Technique For Solving The Triangle Routing Problem In Mobile IP
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1. Introduction
The two most powerful technology trends nowadays (The Internet and Mobile
Communication) are redefining the idea of how and when people access information. Now,
new devices like cellular phones and laptops and business practices are pushing the need for
"always on IP connectivity", or in other words the desire to have continuous network
connectivity to the internet regardless of the physical location of the node. The internet
protocol (IP) requires that hosts on any network have stationary IP addresses, by which the
host is uniquely identified. However, problems rise when a host starts to move away from its
Home Network since it has to change its IP address. Since the IP protocol requires that each
host has a fixed IP address in order to be reached, the moving host will no longer be
reachable [1].
Mobile IP is an open standard, defined by the Internet Engineering Task Force (IETF)
RFC 2002, that allows users keep the same IP address, stay, connected, and maintain ongoing
applications while roaming between networks, given that any media that can support IP can
support Mobile IP. Efforts were made to enhance the standard protocol and to be able to
achieve data transmission within the wireless infrastructure. However, in trying to achieve
this goal many problems have emerged and still proposals to solve them are evolving [2].
The key feature of Mobile IP design is that all required functionalities for processing
and managing mobility information are embedded in well-defined entities, the Home Agent
(HA), Foreign Agent (FA), and Mobile Nodes (MN). The Mobile Node is a host or router that
can change its location from one link to another without changing its IP address or
interrupting existing services. The Home Agent is a router with an interface on a Mobile
Node's home link that intercepts packets destined for the home address. It tunnels packets to
the mobi1e nodes most recently reported Care-of-Address. The Foreign Agent is a router on a
Mobile Node's visited network that provides routing services to the Mobile Node while it is
registered [3, 4].
Suppose that a Mobile Node moves from its Home Network to a Foreign Network, the
correct delivery of packets to its current point of attachment depends on the Mobile Node's IP
address, which changes at every new point of attachment. Therefore, to ensure packet delivery
to the Mobile Node, Mobile IP allows the Mobile Node to use two IP addresses: The Home
address and Care-of-Address (CoA) which is static and is used for instance, to identify TCP
connections. CoA changes at each new point of attachment and can be thought of as the
Mobile Node's topologically significant address. Whenever the Mobile Node is not attached
to its Home Network, the Home Agent gets all the packets destined for the Mobile Node and
arranges to deliver them to the Mobile Node's current point of attachment [2].
Triangle Routing Problem is considered as one of the main problems facing the
implementation of Mobile IP such as, when a Communicating Node (CN) sends traffic to the
Mobile Node, packets first get to the Home Agent, which encapsulates these packets and
tunnels them to the Foreign Agent. The Foreign Agent de-tunnels the packets and delivers
them to the Mobile Node. The route taken by these packets is triangular in nature, and the
most extreme case of routing can be observed when the Communicating Node and the Mobile
Node are in the same subnet [5, 6]. In recent literature, many protocols have been invented to
solve the Triangle Routing problem such as; Forward Tunneling and binding cache, Dynamic
Address Allocation, Bidirectional Route Optimization, and Internet Service Provider Points of
Presence (ISPPoPs) [7, 8, 9, 10].
This paper proposes a technique for solving Triangle Routing Problem in Mobile IP
based on using a number of Internet Service Providers (ISPs) separated by a multiple Mobile
IP Border Gateways (MBGs). The Internet Service Provider is allocated to provide services
for a definite number of geographical areas, each area is composed of a fixed number of zones
served by a fixed number of Points of Presence (PoPs), each PoP serving a number of nodes](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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A Proposed Technique For Solving The Triangle Routing Problem In Mobile IP
- 1. A Proposed Technique for Solving the Triangle Routing Problem in Mobile IP Eng. Sherif Kamel Hussein Ph.D. Student A. Prof. Imane Aly Saroit Ismail Information Technology Department Faculty of Computers and Information Cairo University Prof. S. H. Ahmed Vice Dean Faculty of Computers and Information Cairo University Abstract: Mobile IP has seen slow deployment for two major reasons; the need for enhancing edge routers with Home Agent/Foreign Agent functionality and the fact that triangle routing in such systems is not efficient. Triangle Routing is defined as the route that must be taken through the Home Agent for any traffic sent by the Correspondent Node to the Mobile Node. This route is triangle in nature and longer than the normal path between the Corresponded Node and the Mobile Node. Many protocols and research efforts have been developed to solve this problem. This paper proposes a technique called Internet Service Provider Mobile IP Border Gateway (ISP MBG) for solving the Triangle Routing Problem in conventional Mobile IP protocol using the Internet Service Providers separated by a Mobile IP Border Gateways (MBGs). This proposed technique has been implemented and tested on the Microsoft.net platform. Simulation results prove that the new framework has solved the Triangle Routing Problem in Mobile IP by providing a shorter route with a minimum transmission time for all the datagrams transferred between the Correspondent Nodes and the Mobile Nodes. Keywords: Mobile IP, Triangle Routing Problem, Route Optimization, Internet Service Provider, Point of Presence, Mobile IP Border Gateway, PoPs Virtual Network. Abbreviations:Correspondent Node (CN), Care-of-Address (CoA), Foreign Agent (FA), Home address (Ha), Home Agent (HA), Internet Service Provider (ISP), Mobile Node (MN), Point-of-Presence (PoP), Mobile IP Border Gateway (MBG), PoPs Virtual Network (PVN). â«Ù ÙŰȘ۱Ű⏠â«Ùۚ⏠â«ŰŁŰłâŹ â«Ù ŰȘŰ۱Ù⏠â«Ű§âŹ â«Ű§Ű„ÙŰȘ۱ÙŰȘ⏠â«ÙÙ⏠â«ŰšŰ±ÙŰȘÙ⏠â«ÙÙ⏠â«Ű«Ù⏠â«Ù ۫⏠â«Ű§âŹ â«Ù ۳ۧ۱⏠â«Ű§âŹ â«Ű©âŹ â«Ù ێ⏠â«ŰÙ⏠â«ŰšâŹ Ùâ«Ű§âŹ â«Ű±âŹâ«Ű§Ű±âŹâ«ŰŽâŹâ«Ű§ÙŰȘ⏠â«Ù ŰȘŰ۱Ù⏠â«Ű§âŹ â«ÙŰȘâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«ÙÙ⏠â«ŰšŰ±ÙŰȘÙ⏠â«ŰŁŰšŰŻÙ⏠â«Ùۯ⏠â«Ù⏠â«Ű§âŹâ«ŰŠâŹ â«Ű±âŹ â«Ű§ŰŻÙâŹâ«ŰâŹâ«ŰȘ⏠â«Ű§Ù⏠â«ŰȘ⏠â«Ű§Ű±ÙâŹâ«ÙâŹâ«Ű§ÙŰŰȘ⏠â«ÙÙۧâŹ:â«Ű§âŹ â«Ű§ÙÙâŹâ«Ù âŹâ«Ù Ù⏠â«Ű§ŰšŰšÙÙâŹâ«ŰšâŹ â«Ű§Ù⏠â«Ù۰⏠â«ŰąâŹ â«Ű§ŰŻŰŻÙâŹâ«ŰâŹâ«Ù ⏠â«ŰŻŰ§ŰĄâŹ â«ŰšâŹ:â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«ÙÙ âŹ â«Űčۧ⏠â«Ű§ŰȘ⏠â«Ű±âŹâ«Ű§Ű±âŹâ«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ⏠â«Ű§âŹ â«Ű§ŰąâŹ â«Ű§Ű±ÙÙۧâŹâ«Ű§âŹâ«Ű§âŹâ«Ű§âŹ â«Ű§âŹ â«Ű§ÙۧÙâŹâ«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«ÙÙâŹ:â«Ű§âŹ â«ÙÙ ÙÙ⏠â«Ű§ÙŰčۧâŹâ«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«Ű±âŹ â«Ű§Ű±âŹâ«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«Űș⏠â«Ű§âŹ â«ŰŻŰ§ŰĄâŹ â«Ű§Ű±âŹâ«Ű§âŹâ«Ű§âŹ â«Ù ŰȘ⏠â«Ù⏠â«Ű§âŹâ«Ű§âŹâ«Ű§âŹâ«Ù ⏠â«ÙâŹ:â«Ű§âŹ â«Ű§Ű°ŰŁâŹâ«Ű§âŹâ«Ű§âŹâ«Ù⏠â«Ű§Ű±Ű±âŹâ«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ⏠â«Ű§âŹ â«Ű§âŹâ«Ű§âŹâ«Ű§âŹâ«ŰŽâŹâ«Ù ⏠â«Ű§ŰŻâŹâ«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«Ű§âŹâ«ÙâŹâ«ŰȘ⏠â«Ű§âŹâ«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«ŰȘÙ⏠â«Ű§ÙâŹâ«Ű§âŹâ«Ű§âŹ â«Ù ۧ⏠â«Ű§âŹ â«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«Ű±âŹâ«ŰȘÙ⏠â«Ű§ÙâŹâ«Ű§âŹ â«ÙÙÙ âŹ â«Ű§ÙâŹâ«Ű§âŹâ«Ű§âŹ â«Ù ۧ⏠â«Ű§âŹ â«Ű§Ű±Ű±âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ⏠â«Ű§âŹ â«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«ŰŁâŹ â«Ű§ÙâŹâ«Ű§âŹ â«Űč⏠â«Ű§ŰŻŰčâŹâ«Ű§âŹâ«ÙâŹâ«Ù⏠â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹ â«ŰȘ⏠â«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ۱⏠â«Ű§âŹ â«Ű§ŰŻŰčâŹâ«Ű§âŹâ«ÙâŹâ«Ù⏠â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«Ù ⏠â«Ű§ÙâŹâ«Ű§âŹâ«ŰšâŹâ«ŰȘ۱⏠â«Ű§ÙâŹâ«Ű§âŹâ«ŰȘ⏠â«Ű§âŹ â«Ű§Ű±ŰȘâŹâ«Ű§âŹâ«ÙâŹâ«ŰšÙ۱⏠â«Ű§âŹ â«Ű§âŹâ«Ű§âŹâ«ÙâŹâ«ŰȘŰȘۚ⏠â«Ű§Ű°ÙâŹâ«Ű§âŹ â«Ű§âŹ â«Ű§Ű±Ű±âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ⏠â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«ŰšâŹâ«ŰšŰ±âŹ:â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«ÙâŹâ«ÙÙ âŹ â«Ű§âŹ â«Ű§Ű±âŹâ«Ű§âŹâ«ŰšâŹâ«Űč⏠â«Ű§Ű±Ù۱âŹâ«Ű§âŹâ«Ù ⏠â«Ű§âŹ â«Ű§Ű±ÙâŹâ«Ű§âŹâ«Ù ⏠â«Ű§ÙâŹâ«Ű§âŹâ«Ù ⏠â«Ű§ÙâŹâ«Ű§âŹ â«Ù۰⏠â«Ű§âŹâ«Ű§âŹ â«Ù ŰȘŰ۱⏠â«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«Ű⏠â«Ű§Ű°ÙâŹâ«Ű§âŹâ«ŰšâŹ â«Ű§ŰŻâŹâ«Ű§âŹ Ùâ«Ű±âŹâ«Ű§âŹâ«Ű§âŹ â«ŰÙ⏠â«Ù ⏠Ùâ«Ű§âŹâ«Ű§ÙŰŻâŹâ«Ű§âŹâ«ÙâŹâ«Ù Ù⏠â«Ű§Ű±ÙâŹâ«Ű§âŹâ«Ù⏠â«ŰŁÙ⏠â«Ű±âŹ â«Ű§Ű°âŹâ«Ű§âŹ â«ŰšŰ±âŹ â«Ű§ŰŻÙ۱âŹâ«Ű§âŹâ«Ù⏠â«Ű§ÙâŹâ«Ű§âŹ â«Ű§Ű±âŹâ«Ű§âŹâ«Ù âŹâ«ÙÙ âŹ â«Ù ۧ⏠â«Ű§âŹ â«Ù ۚ۱۱⏠â«Ű§âŹ â«Ù ێ⏠â«ÙŰȘâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«ÙÙ⏠â«ŰšŰ±ÙŰȘÙ⏠â«Ù⏠â«Ű§Ù⏠â«Ù⏠â«Ű§âŹ â«Ű±âŹâ«Ű§âŹâ«Ű§âŹâ«ŰȘ⏠â«Ű§âŹ â«Ű§ŰȘÙ âŹâ«Ű§âŹâ«Ù⏠â«Ű§âŹâ«Ű§âŹâ«ŰâŹâ«ŰšâŹ â«Ű§âŹ â«Ű§Ű°Ű§âŹâ«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹ â«Ù⏠â«Ű§âŹâ«Ű§âŹâ«ŰšâŹâ«ŰŁâŹ â«Ű§ŰŻÙâŹâ«Ű§âŹâ«Ù⏠â«ŰȘÙ⏠â«Ű§âŹ â«Ű§Ű±ÙâŹâ«Ű§âŹâ«ŰâŹâ«Ù ŰȘ⏠â«Ű§âŹ â«Ű§ŰȘâŹâ«Ű§âŹâ«ÙâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«Ű§ÙÙâŹâ«Ű§âŹ â«ŰšŰ±ÙŰȘÙ⏠â«Ű§ÙâŹâ«Ű§âŹ â«Ű§ÙâŹâ«Ű§âŹâ«Ű§âŹ â«Ù ۧ⏠â«Ű§âŹ â«Ű§Ű±Ű±âŹâ«Ű§âŹâ«ŰšâŹâ«Ù ⏠â«Ű§âŹ â«Ű§âŹâ«Ű§âŹâ«ŰŽâŹâ«Ù ⏠â«Ű§ÙâŹâ«Ű§âŹâ«Ű⏠â«Ű§Ű±âŹâ«Ű§âŹâ«Ù ⏠â«Ű§ÙâŹâ«Ű§âŹ â«Ù⏠â«ÙŰšÙ Ù⏠â«ÙÙ⏠â«ŰšŰšŰ±ÙŰȘÙ⏠â«Ű§ŰŻÙŰŻâŹâ«Ű⏠â«Ű§âŹ â«Ű§Ű±ŰȘâŹâ«ŰšâŹâ«Ű§âŹâ«ÙâŹâ«ŰšâŹ â«Ű°Ű§ŰȘ⏠â«ÙŰȘâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«Ù ŰŻÙ Ű±ŰȘ⏠â«Ù ŰČÙŰŻÙ⏠â«Ű§Ű±âŹâ«ŰȘâŹâ«Ù Ù⏠â«Ű§âŹ â«Ù⏠â«Ű§âŹâ«ŰšâŹ:â«Ű§âŹ â«Ű§ŰŻâŹâ«Ù âŹâ«ÙÙÙŰȘ⏠â«Ű§ŰČÙŰŻÙâŹâ«Ù ⏠â«Ű§ÙâŹâ«Ù ⏠â«Ű§ŰŻâŹâ«ÙâŹâ«Ùۯ⏠â«Ű§âŹ â«Ű§ŰȘÙ ŰŻŰ§Ù âŹâ«ŰšâŹâ«Ű§âŹ â«Ű§Ù⏠â«Űč⏠â«Ű§âŹâ«Ù⏠â«Ű§ŰȘâŹâ«Ű§âŹâ«ÙâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«Ű±ŰȘ⏠â«Ű§ŰšâŹâ«Ű§âŹâ«ŰŽâŹ â«Ű§âŹâ«Ű§âŹâ«Ù âŹâ«Ù ۯ⏠â«Űč⏠â«Ű§Ű±ÙâŹâ«Ű§âŹâ«ŰâŹâ«Ù ŰȘ⏠â«Ű§âŹ â«Ű§ŰȘâŹâ«Ű§âŹâ«ÙâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«Ű§ÙÙâŹâ«Ű§âŹ â«ŰšŰ±ÙŰȘÙ⏠â«Ű§ŰŻÙŰŻâŹâ«Ű§âŹâ«Ű⏠â«Ű§âŹ â«Ű§Ű±ŰȘâŹâ«Ű§âŹâ«ŰšâŹâ«Ű§âŹâ«ÙâŹâ«ŰšâŹ â«Ű§ŰȘÙ ŰŻŰ§Ù âŹâ«Ű§âŹâ«ŰšâŹâ«ŰšŰ±âŹ â«Ű§Ù۱âŹâ«Ű§âŹâ«ŰłâŹâ«ŰšÙ⏠â«Ű§ÙâŹâ«Ű§âŹâ«Űč⏠â«Ű§ÙâŹâ«Ű§âŹ â«ŰȘÙ⏠â«Ű§ÙâŹâ«Ű§âŹâ«ŰȘ⏠MBGs â«Ű§Ű°Ű§âŹâ«Ű§âŹ â«Ű§âŹ â«Ű±Űč⏠â«ÙÙ Ű۱⏠â«Ű§Ù ŰȘۚ۱۱⏠â«ŰȘÙ âŹ â«ŰŻâŹ â«Ù⏠â«Ù ÙŰȘ۱⏠â«Ű§âŹ â«ÙÙ Ù⏠â«Ű§âŹ â«Ű§ŰȘÙ ŰŻŰ§Ù âŹâ«ŰšâŹâ«Ű§âŹ â«ÙÙâŹâ«Ű±âŹ â«ŰčÙ⏠â«ÙŰȘ⏠â«ŰȘ⏠â«Ű§ÙâŹâ«ŰšâŹâ«Ű±Ù⏠â«Ù Ù⏠â«Ű§ŰȘâŹâ«ŰȘâŹâ«ŰŁŰ§ŰšâŹ â«Ű§ŰŻâŹ â«Ù⏠â«Ű§Ű±ŰŠâŹâ«ŰȘâŹâ«Ù⏠â«ŰŁÙ⏠â«Ű§Ű±Űč⏠â«Ù Ű۱⏠â«Ű§âŹ â«Ű§Ű±âŹâ«ŰȘâŹâ«Ù Ù⏠â«Ű§âŹ â«Ù⏠â«Ű§âŹâ«ŰšâŹ:â«Ű§âŹ â«Ű±Ù ⏠â«ŰŻâŹ â«Ű§âŹâ«Ù⏠â«ŰȘÙ⏠â«Ű§âŹ â«Ù ŰȘŰ۱Ù⏠â«Ű§âŹ â«ÙŰȘâŹâ«Ű±âŹâ«Ű§Ű„ÙŰȘ⏠â«ÙÙ⏠â«ŰšŰ±ÙŰȘÙ⏠â«Ù⏠â«Ű§Ù⏠â«Ù ۧ⏠â«Ű§âŹ â«Ù ۚ۱۱⏠â«Ű§âŹ â«Ù ێ⏠â«ŰšŰÙ⏠â«Ű§ÙâŹâ«Ù⏠â«ŰȘÙ⏠â«Ű§âŹâ«Ù ⏠â«Ű§Ű±âŹ â«ŰŁâŹ â«Ű§Ű±Ű±âŹâ«ŰšâŹâ«Ù ⏠â«Ű§Ű±Ű§âŹâ«ŰšâŹâ«ŰȘŰȘ⏠â«Ű§ÙâŹâ«ÙâŹâ«Ű±âŹ â«Ű§ÙâŹâ«Űč⏠â«Ű§Ù⏠â«Ù۰⏠â«ŰŻÙ⏠â«Ù ŰȘŰ۱⏠â«Ű§âŹ â«ÙÙŰŻŰč⏠â«Ű§âŹ â«Ù⏠â«ŰȘ⏠â«Ù ۱ۚ⏠â«Ű§âŹ â«ÙÙŰŻŰč⏠â«Ű§âŹ â«Ù Ù⏠â«Ù ۱ۚ⏠â«Ű§âŹ â«ŰšÙ۱Ù۱ŰȘ⏠â«Ű§âŹ â«ÙÙ Ù⏠â«Ű§Ű„۱ۚ۱Ù⏠â«ŰČÙ ÙâŹ
- 2. - - 2 1. Introduction The two most powerful technology trends nowadays (The Internet and Mobile Communication) are redefining the idea of how and when people access information. Now, new devices like cellular phones and laptops and business practices are pushing the need for "always on IP connectivity", or in other words the desire to have continuous network connectivity to the internet regardless of the physical location of the node. The internet protocol (IP) requires that hosts on any network have stationary IP addresses, by which the host is uniquely identified. However, problems rise when a host starts to move away from its Home Network since it has to change its IP address. Since the IP protocol requires that each host has a fixed IP address in order to be reached, the moving host will no longer be reachable [1]. Mobile IP is an open standard, defined by the Internet Engineering Task Force (IETF) RFC 2002, that allows users keep the same IP address, stay, connected, and maintain ongoing applications while roaming between networks, given that any media that can support IP can support Mobile IP. Efforts were made to enhance the standard protocol and to be able to achieve data transmission within the wireless infrastructure. However, in trying to achieve this goal many problems have emerged and still proposals to solve them are evolving [2]. The key feature of Mobile IP design is that all required functionalities for processing and managing mobility information are embedded in well-defined entities, the Home Agent (HA), Foreign Agent (FA), and Mobile Nodes (MN). The Mobile Node is a host or router that can change its location from one link to another without changing its IP address or interrupting existing services. The Home Agent is a router with an interface on a Mobile Node's home link that intercepts packets destined for the home address. It tunnels packets to the mobi1e nodes most recently reported Care-of-Address. The Foreign Agent is a router on a Mobile Node's visited network that provides routing services to the Mobile Node while it is registered [3, 4]. Suppose that a Mobile Node moves from its Home Network to a Foreign Network, the correct delivery of packets to its current point of attachment depends on the Mobile Node's IP address, which changes at every new point of attachment. Therefore, to ensure packet delivery to the Mobile Node, Mobile IP allows the Mobile Node to use two IP addresses: The Home address and Care-of-Address (CoA) which is static and is used for instance, to identify TCP connections. CoA changes at each new point of attachment and can be thought of as the Mobile Node's topologically significant address. Whenever the Mobile Node is not attached to its Home Network, the Home Agent gets all the packets destined for the Mobile Node and arranges to deliver them to the Mobile Node's current point of attachment [2]. Triangle Routing Problem is considered as one of the main problems facing the implementation of Mobile IP such as, when a Communicating Node (CN) sends traffic to the Mobile Node, packets first get to the Home Agent, which encapsulates these packets and tunnels them to the Foreign Agent. The Foreign Agent de-tunnels the packets and delivers them to the Mobile Node. The route taken by these packets is triangular in nature, and the most extreme case of routing can be observed when the Communicating Node and the Mobile Node are in the same subnet [5, 6]. In recent literature, many protocols have been invented to solve the Triangle Routing problem such as; Forward Tunneling and binding cache, Dynamic Address Allocation, Bidirectional Route Optimization, and Internet Service Provider Points of Presence (ISPPoPs) [7, 8, 9, 10]. This paper proposes a technique for solving Triangle Routing Problem in Mobile IP based on using a number of Internet Service Providers (ISPs) separated by a multiple Mobile IP Border Gateways (MBGs). The Internet Service Provider is allocated to provide services for a definite number of geographical areas, each area is composed of a fixed number of zones served by a fixed number of Points of Presence (PoPs), each PoP serving a number of nodes
- 3. - - 3 depends on their locations. Virtual networks between PoPs are established to facilitate the accessing of the nodes' information without any redundancy. Having Mobile IP Border Gateways (MBG) between different Internet Service Providers will maintain the data for all the nodes, leaving their local Internet Service Provider and transferred to another Internet Service Provider. Hence the level of security will be increased between them. A simulation was built to evaluate this protocol; the performance of this technique was evaluated and compared with the Conventional Mobile IP technique. The paper is divided into seven sections. Section 2 presents some basic concepts about Mobile IP while Section 3 introduces the concept of the Triangle Routing Problem in Mobile IP. A fast survey of some recent protocols proposed for optimizing the Triangle Routing Problem is also presented. Section 4 presents the proposed ISP MBG technique used to optimize the Triangle Routing Problem in the Conventional Mobile IP technique. Section 5 introduces the analysis and evaluation of the proposed ISP MBG technique compared with the conventional Mobile IP technique. Section 6 presents the concluding remarks. Finally, Section 7 presents the future work. 2. Mobile IP Mobile IP is a modification to IP that allows nodes to continue to receive datagrams no matter where they happen to be attached to the Internet. It involves some additional control messages that allow the IP nodes involved to manage their IP routing tables reliably. Scalability has been a dominant design factor during the development of Mobile IP, because in the future a high percentage of the nodes attached to the Internet will be capable of mobility [5, 11, 12]. 2. 1 Mobile IP Terminologies Concerning the Mobile IP a set of terminologies are considered and defined as follows: Mobile Node (MN) a host or router that changes its point of attachment from one network or subnetwork to another Home address (Ha) an IP address that is assigned for an extended period of time to a Mobile Node in the Home Network. Home Agent (HA) a router on a Mobile Nodeâs Home Network which tunnels datagrams for delivery to the Mobile Node when it is away from home, and maintains current location information for the Mobile Node. Home Network (HN) a network, possibly virtual, having a network prefix matching that of a Mobile Nodeâs Home Address. Foreign Agent (FA) a router on a Mobile Nodeâs Visited Network which provides routing services to the Mobile Node while registered. The Foreign Agent de-tunnels and delivers datagrams to the Mobile Node. Foreign Network (FN) any network other than the Mobile Nodeâs Home Network. Care-of-Address (CoA) the termination point of a tunnel toward a Mobile Node, for datagrams forwarded to the Mobile Node while it is away from home. Correspondent Node (CN) a peer with which a Mobile Node is communicating, it may be either mobile or stationary. Link a facility or medium over which nodes can communicate at the link layer. A link underlies the network layer. Node a host or a router
- 4. - - 4 Tunnel the path followed by a datagram while it is encapsulated Virtual Network a network with no physical instantiation beyond its router (with a physical network interface on another network). Visited Network a network other than a Mobile Nodeâs Home Network to which the Mobile Node is currently connected. Visitor List the list of Mobile Nodes visiting a Foreign Agent. Mobile Binding the association of Home Network with a Care-of-Address, along with the remaining lifetime of that association 2. 2 Operation of Mobile IP Mobile IP is doing the following three relatively separate functions: Agent Discovery, Registration and Tunneling [11, 12]. 2. 2. 1 Agent discovery The discovery process in Mobile IP is very similar to the router advertisement process defined in Internet Control Message Protocol (ICMP). For the purpose of discovery, a router or another network node that can act as an agent periodically issues a router advertisement ICMP message with an advertisement extension [11, 12]. 2. 2. 2 Registration Once a Mobile Node has recognized that it has transferred on a Foreign Network and has acquired a Care-of-Address, it needs to alert a Home Agent on its Home Network and requests that the Home Agent forwards its IP traffics. The registration process involves four steps: Registration Request to Foreign Agent, Foreign Agent Relays the Request to Home Agent, Registration Reply from the Home Agent to the Foreign Agent and finally the Foreign Agent Relays the Reply to the Mobile Node [11, 12]. 2. 2. 3 Tunneling Once a Mobile Node is registered with a Home Agent, the Home Agent must be able, to intercept IP datagrams sent to the Mobile Nodeâs Home Network so that these datagrams can be forwarded via tunneling. In the most general tunneling case as shown in Figure 1; the source, the encapsulator, the decapsulator and the destination are separate nodes. The encapsulator node is considered the entry point of the tunnel, while the decapsulator node is considered the exit point of tunnel. Multiple source-destination pairs can use the same tunnel between the encapsulator and decapsulator [11, 12]. Figure 1. General Tunneling Three options for encapsulation (tunneling) are available for use by the Home Agent on behalf of the Mobile Node mainly: IP-ln-IP Encapsulation, Minimal Encapsulation, and General Routing Encapsulation (GRE). Encapsulation Source Decapsulation Destination Tunneling
- 5. - - 5 2. 3 Mobile IP Operation Sequence With the three relatively separated functions; Agent Discovery, Registration and Tunneling; a rough outlines of the operation of Mobile IP Protocol is described as shown in Figure 2 [5]. Figure 2. Mobile IP Operation Sequence Mobile agents (Foreign Agents and Home Agents) advertise their presence via agent- advertisement messages. A Mobile Node receives an agent advertisement and determines whether it is on its Home Network or a Foreign Network. When the Mobile Node detects that it is located on its Home Network, it operates without mobility services. When a Mobile Node detects that it has moved to a Foreign Network, it obtains a CoA on the Foreign Network. The CoA can be either a Foreign Agent CoA or a Co-located CoA, then the Mobile Node registers its new CoA with its Home Agent through the exchange of a registration request and registration reply message, possibly by way of a Foreign Agent. Datagrams sent to the Mobile Nodeâs Home Network are intercepted by its Home Agent, tunneled by the Home Agent to the Mobile Nodeâs CoA, received at the tunnel endpoint (either at a Foreign Agent or at the Mobile Node itself), and finally delivered to the Mobile Node. In the reverse direction, datagrams sent by the Mobile Node may be delivered to their destination using standard IP routing mechanisms, without necessarily passing through the Home Agent. 3. Triangle Routing Problem One of the basic problems facing the implementation of Mobile IP is the Triangle Routing Problem, since all the traffics between CN and MN should have to pass through a longer path than the normal one. This section introduces the definition and the drawbacks of the Triangle Routing Problem as shown in the following supsections. 3. 1 Triangle Routing Definition Triangle Routing Problem is considered as one of the problems facing the implementation of Mobile IP. When a CN sends traffics to a MN, the following sequence must be done: 1. Packets first get the HA. 2. Home Agent encapsulates these packets and tunnels them to the FA. 3. The Foreign Agent de-tunnels the packets and delivers them to the Mobile Node. Foreign Network 5.a. Reg. Request 5.d. Reg. Reply HOME AGENT 3. Mobility Binding MOBILE NODE FOREIGN AGENT 4.Visit list 5.b. Reg. Request 5.c. Reg. Reply Correspondent Node 7. Datagrams sent from MN to CN Data to Mobile Node Intercepted by HA 6. 2. Received Agent Advertisement 1. Send Agent Advertisement 1. Send Agent Advertisement
- 6. - - 6 As shown in Figure 3, the route taken by these packets is triangle in nature, and the most extreme case of routing can be observed when the Correspondent Node and Mobile Node are in the same subnet [7, 16]. Figure 3. Illustration of the Triangle Routing Problem in Mobile IPv4 3. 2 Triangle Routing Drawbacks Conventional Mobile IP technique allows transparent interoperation between Mobile Nodes and their Correspondent Nodes, but forces all datagrams for a Mobile Node to be routed through its Home Agent. Thus, datagrams to the Mobile Node are often routed along paths that are significantly longer than optimal. This indirect routing can significantly delay the delivery of the datagrams to Mobile Nodes, and it places an unnecessary burden on the networks and routers along its path through the internet. The Triangle Routing drawbacks can be mentioned as follows: 1. Increases the delays per packet in datagrams transferred to the Mobile Node. 2. Wastes the network resources. 3. Home Agent bottle neck. 4. Delimits the scalability of Mobile IP protocol. 3. 3 Triangle Problem's Previous Solutions Several research efforts were done to eliminate or address the Triangle Routing Problem in Mobile IP [7, 8, 9, 10, 11, 12, 13, 14]. Some of such efforts are briefly mentioned as follows: [17, 18] presented a route optimization protocol which was developed to solve the Triangular Routing Problem, by allowing each host to maintain a binding cache for a mobile host wherever it is [7]. This Route Optimization technique provides a smooth handoff when the Mobile Node moves and registers with a new Foreign Agent. [8] presented a technique with an extension to the Mobile IP architecture. In this technique, one Mobile Station (MS) is to handle two IP addresses between internet and intra- domain, one is called a Current Address (CA) and another one is called a Register Address (RA). Location Agent (LA) is a router responsible for translating both addresses between internet and intra-domain. Register Address is used for packets routing in internet; Current Address is used for packets in intra-domain. Mobile Agent (MA) is router on a Mobile Station's current network which delivers packets to Mobile Station, it has a functionality similar to FA and HA. Hard handoff technique is proposed to be used with this technique. Also, a âpacket retransmissionâ technique is used to avoid packet loss while hard handoff. [9] presented a technique to support symmetric bidirectional route optimization in Mobile IP considering ingress-filtering routers [19]. Subnet-based direct tunneling techniques CN MN FA HA Datagram MN-CN Datagram CN- MN Detunneld Tunneled datagram 1 2 3
- 7. - - 7 are proposed to improve the routing efficiency for Mobile IP and a binding optimization technique to reduce the handoff latency for Mobile Nodes. An enhanced correspondent agent was introduced to collaborate with the Home Agent and the Foreign Agent to support these techniques. Correspondent Agent will maintain the binding cache and intercepts all packets sent to and from the Correspondent Nodes. Symmetrically, a Foreign Agent, at the other end of the optimized route or tunnel, maintains a tunneling cache for bidirectional route optimization. [10] mentioned that, the basic idea in optimizing Triangle Routing is to get the HA as close as possible to the MN, when the MN no longer in its Home Network. This is achieved by shifting the Home Agent into the ISP's Domain. The ISP's network makes the Mobile IP "aware" by enhancing ISP Points of presence (PoPs) and by creating a virtual network composed of PoPs to distribute the state information about the MN at the original HA to all PoPs. This ensures that no matter where the MN is, the HA is just a PoP away. [11] presented a modified encapsulation technique is modified to give a better delay performance for Mobile IP. Instead of encapsulation at the home agent, the encapsulation is done at one level up in a hierarchical network. This reduces the delay of traveling the same link twice. The processing delay is also reduced, as the processing is not centralized at the home agent. [12] has proposed certain extensions to Mobile IP to support route optimization. A drawback of the proposed route optimization extensions to Mobile IP is the requirement for the CN to be mobility aware. In this paper, the authors propose a port address translation based route optimization technique. The proposed route optimization technique attempts to reduce the overhead and delay involved with traditional mobile communication by means of using port address translation (PAT) and routing the packet using an optimal path. [13] presented a route optimization agent based, which moves the tasks of maintaining and updating binding caches and encapsulating messages away from individual correspondent nodes to the correspondent agents. A simulation environment has been setup to evaluate the proposed methodology. Simulation results show that the proposed protocol outperforms the existing protocols in terms of system message complexity, protocol simplicity, and scalability. [14] mentioned that a permanent home address is not really necessary for many Internet applications on a mobile host. Also, a mobile host's mobility is highly localized during a certain period of time. By having a foreign network within a mobile host's localized footprint to be it's virtual home network, it can greatly alleviate the triangle routing problem because of the mobility locality nature, and, at the same time, enable the mobile host to communicate with any conventional Internet hosts that are not mobility aware. 3. 4 Previous Route Optimization Techniques Drawbacks in Mobile IP The great effect of using the Route Optimization techniques is to minimize the transmission time (delay) between Correspondent Node (CN) and Mobile Node (MN) because of the shortest path to reach Mobile Node and also to reduce the traffic and control signals over the network. The drawbacks of the most Route Optimization techniques are classified as follows: 1. Rigid requirements for an authentication of the clamed Care-of-Address especially when both of Mobile Node and Correspondent Node are in different IP networks. 2. Increase the cost of hardware devices needed for the Route Optimization functions.
- 8. - - 8 3. Increase the amount of traffics over the network. 4. Increase the rate of buffering and storage buffers. 5. Increase the rate of blocking especially when the number of connections to Mobile Nodes is increased which results in increasing in the transmission time between Correspondent Node (CN) and Mobile Node (MN). 4. A Proposed Technique for Solving the Triangle Routing Problem Before discussing the proposed technique it is important to mention the types of communications in Mobile Networks. In this issue, communication types involve the following [20]: 1. Communication between Mobile Node (MN) and Correspondent Node (CN) within the same Network; in this case the Home Agent receives a packet destined to the Mobile Node from a Correspondent Node and both of MN and CN are in the same network as shown in Figure 4. Figure 4. Connection between Two Mobile Terminals in the Same Network 2. Communication between Mobile Node (MN) and Corresponded Node (CN) in two different Networks; when both of the Mobile Node and Correspondent Node are located in different networks as shown in Figure 5. It is supposed for the binding information to be transferred between the two networks and that will lead to a security related problem. To solve this problem, Mobile IP Border Gateways (MBGs); which are devices within the mobile networks; will maintain the binding information that must be added to the Correspondent Node without adding functions to terminals in the external networks [20, 21, 22]. Figure 5. Connection between Mobile Terminal and Correspondent Node in two Different IP Networks Other IP network Mobile IP network Mobile Terminal FA FA HA Gateway Correspondent Node HA: Home Agent FA: Foreign Agent Mobile IP Core network HA FA FA Mobile Terminal Mobile Terminal HA : Home Agent FA: Foreign Agent
- 9. - - 9 4.1 Objectives of the Proposed Technique The main objective of the proposed technique is to solve the Triangle Routing Problem in the Conventional Mobile IP technique. The proposed technique aims are: 1. minimizing the average message delay. 2. maximizing the network throughput (minimize the network blocking rate). 3. using the network resources efficiently and eliminating the Home Agent (HA) processing bottleneck due to the fact that all communication from Correspondent Node (CN) to Mobile Node (MN) are necessarily routed through the Home Agent (HA). 4. increasing the level of security between different networks by using the Mobile IP Border Gateway (MBG). This is important for maintaining the information that being used by the Correspondent Node (CN) such as incoming packets from the external network are tunneled or routed and delivered directly to the Mobile Node (MN) instead of routing through the Home Agent (HA). 4. 1. 1 Architectural design of the proposed technique Figure 6 presents the overall design of the proposed ISP MBG technique for the Route Optimization Problem. Figure 6. Global Views for the Proposed ISP MBG Technique with an Example of PVN The design introduces the following: 1. Having a number of N Internet Service Providers ISP1, ISP2,âŠâŠ.., ISPN each covers a definite and different geographical place. They are separated by an L Mobile IP Border Gateways (MBGs) [20]. MBGs will maintain either the binding (Home address, Care-of- Address) or only the home information (Home address) for all the transferred nodes (Mobile Nodes) from one Internet Service Provider to another. That depends on whether we are using tunneling or routing technique to forward the traffics generated in one Internet Service Provider and destined to Mobile Node located in another Internet Service Agent 1 MBGL ISP2 ISPN MBG1 ISP1 ISPN-1 PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK Zone 1 Zone 2 Zone M PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK Agent 2 Agent S-1 Agent S Area 1 Area 2 Area S-1 Area S PVN1
- 10. - - 10 Provider. Also, using multiple MBGs will distribute uniformly the processing load among them. 2. Each Internet Service Provider is divided into a number of approximately S equal areas. Each area is served by an Agent that is considered as Home Agent for the nodes within that area and as Foreign Agent for all the nodes transferred from the other areas. 3. Each area is divided into multiple equal M zones where each zone is served by a fixed K equal number of Points-of-Presence (PoPs). Figure 7 shows an example of the areas and PoPs classifications of each area for an Internet Service Provider. Figure 7. PoPs Classifications for ISP 4. For each Internet Service Provider assuming that we have K PoPs virtual networks (PVNs) that can be placed in a fashion that is similar to (Ping-Pong) overlay network creation. This virtual network handles state information about all Mobile Nodes and Correspondent Nodes. For example, when a Mobile Node registers with one Points-of- Presence (PoPs), in one of the defined zones, the registration information will be available to all other zones through the PVN connecting that PoP with the other equivalent PoPs in the other zones. Figure 8 shows an example of PoPs Virtual Networks (PVNs) for ISP. PVNi ïąiï1..k PoPi(Area1,Zone1), PoPi (Area1,Zone2),âŠ, PoPi (Area1, ZoneM), PoPi (Area2,Zone1), PoPi (Area2,Zone2), âŠ., PoPi (Area2,ZoneM),âŠ.., PoPi (Areas ,Zone1), PoPi (AreaS,Zone2)âŠâŠ. PoPi (AreaS,ZoneM). Figure 8. PVNs for ISP 5. Each PoP serving a definite X number of nodes with a range W of addresses. The nodes that are within the same agent serving the PoP are called Local Nodes and those are in different agents, and transferred to the agent serving that PoP; are called External Nodes. The range of W addresses for each PoP is divided as follows: 1. A addresses for local nodes that are in service (Home address) 2. B addresses for local nodes that are in waiting (Home address) 3. C addresses for external nodes that are in service (Care-of- Address) 4. D addresses for external nodes that are in waiting (Care-of-Address) ISP Area 1 (Agent 1) Area 2 (Agent 2) Area S-1 (Agent S-1) Area S (Agent S) Zone 1 Zone 2 Zone M-1 Zone M PoP 1 PoP 2 PoP K-1 PoP K
- 11. - - 11 4. 1. 2 Sequences of the propose technique When a node is generated, it will be supported by the PoP serving its position, all of the home information concerning that node will be saved at that PoP. When a Mobile Node (MN) moves to another area or agent, the new agent will provide the node with the Care-of-Address. The home information for the node in the new position could be accessed through the PoP Virtual Networks (PVNs) that connects the node's home PoP to its new position serving the PoP. Figure 9 shows the operation sequence of the proposed technique. The operation sequence for the proposed algorithm depends on whether both of the Correspondent Node and the Mobile Node are located in the same Internet Service Provider or both belong to different Internet Service Providers. So, when Correspondent Node needs to establish connection with the Mobile Node we have the following cases: 1. Both CN and MN belong to the same Internet Service Provider. a. CN connects to its home PoP (Pk-1)asking about the information for the Mobile Node. b. The correspondent PoP searches its neighboring PoPs (P1, P2,âŠ.Pk-2, Pk) in the same Zone, one of them is guaranteed to be connected to the virtual network of the Mobile Node. c. The PoP which is connected to the Mobile Node's Virtual Network (i.e. P1) connects directly to the Mobile Node and the connection is established. 2. Both CN and MN belong to different Service Providers a. The Mobile IP Boarder Gateway will keep the home information (Home address) for all the Mobile Nodes that are transferred form one ISP to another. b. The Correspondent Node connects to its home PoP (Pk-1) asking about the information for the Mobile Node. c. The Correspondent PoP will ask its neighboring PoPs (P1, P2,âŠ.Pk-2, Pk) about the Mobile Node's home information. One of the PoPs (P1) is guaranteed to be connected to the virtual network of Mobile Node. d. The PoP which is connected to the MN's Virtual Network (i.e. P1) connects to MBG which has the original home information for the destined MN. MBG connects to the nearest PoP in the destination ISP which is connected to the new virtual network of Mobile Node e. The connection is established between Correspondent Node and Mobile Node. ISP1 ISP2 Figure 9. Operation Sequence for the Proposed Technique Agent 1 PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK PoP1 PoP2 PoPK-1 PoPK Agent 2 Area 1 Area 2 MBG Home information for the transferred MN (Agent, Area, Zone, PoP) MN1 MN2 CN PVN 1.c 2.e 2.d 2.a 1.a 2.b 1.b 2.c
- 12. - - 12 5. Evaluation of the Proposed Technique Simulation modeling is based on system programming such as data structures, flowcharts, programming languages and other tools that can be used to build up and characterizing system performance. For simplicity, it is preferable to depend on the simulation model. 5. 1 System Parameters The key point for establishing any system is to define its main parameters. This section introduces the simulation parameters, data structure and connection parameters for the designated system respectively in the following three subsections: 5. 1. 1 Simulation parameters A network with two Internet Service Providers is considered, each with two similar areas. Each area is divided into two equal zones, where each zone is served by four PoPs. Each PoP actually is serving 20 nodes with 30 addresses. The addresses are classified as 20 addresses for the nodes in service and 10 addresses for the nodes in waiting. The addresses for the nodes in service are classified as 15 addresses for the local generating nodes and 5 addresses for the externally generating nodes. By the same way for the addresses concerning the nodes in waiting. They are classified as 5 addresses for the local generating nodes and 5 addresses for the externally generating nodes. The addresses for the nodes are considered as integer numbers given to each node consecutively and depend on the location of the node, area, zone, PoP, and ISP it belongs to. Figure 10 shows an example of the nodes and address classification for PoPi of the address classification for both PoP1 and PoP2 of area1, zone1 and ISP1. The total number of Zones all over the architecture design is 8 zones, each zone with 4 PoPs. The total number of PoPs is 32 PoPs and can be calculated by the following equation: PN = PK x NZ where; PN is the total number of PoPs PK is the number of PoPs within the Zone NZ is the total number of Zones Because of the total number of PoPs all over the architectural design is 32 PoPs and each PoP is serving 20 nodes, the simulation is done for a total number of nodes equals to 640 nodes. NT = PN x NC where; NT is the total number of generating nodes NC is the number of generating nodes in each connection. Figure 10. Nodes and Address Classifications for PoPi PoP i N1 N15 N16 N20 N21 N25 N26 N30 1-------15 Locally in services 16-----20 Locally in waiting 21-----25 Externally in services 21-----25 Externally in waiting
- 13. - - 13 5. 1. 2 Data structures The main data structures implemented in the simulation are: nodes, PoPs, ISPs, Areas, Agents, and Mobile IP Border Gateway (MBG). The class definitions and the structure definitions for all the data structures are implemented using C Sharp on the Microsoft.net platform. 5. 1. 3 Connection parameters For the wireless communication design and implementation of the proposed technique, the connection parameters for the implemented algorithm are the key point for running the program. The connection parameters can be classified as follows: 1. The distance in kilometers equivalent to the distance of 1 pixel. 2. Link speed for PoP connection 3. Link speed for Agents connection 4. PoP nodes count to serve. 5. PoP nodes count to wait 6. Agent nodes count to serve 7. Agent nodes count to wait 5. 2 System Construction Figure 11 shows the design architecture of the proposed ISP MBG technique. Each PoP can be identified using the following three parameters respectively; ISP number, Agent number and Zone number: Pi = PoPj,k,l i = j,k,l where; Pi: the ith PoP j : Internet Service Provider number k : Agent number l : Zone number Also, we have two similar PoPs Virtual Networks (PVNs) for the two Internet Service Providers. Each is classified as follows: the first one connects all PoPs1, the second one connects all PoPs2, the third one connects all PoPs3 and finally the fourth one connects all PoPs4. ISP 1 ISP2 Figure 11. Design Architecture Zone 1 Agent 1 Zone 2 Zone 3 Agent 2 Zone 4 Zone 1 Agent 3 Zone 2 Zone 3 Agent 4 Zone 4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 P1 P2 P3 P4 MBG (1) (2) (3) (4)
- 14. - - 14 ï„ ï ï« ï ïą 1 1 ..... ) , ( z i m m m P P D ï„ ï ï« ï ïą 1 1 ..... ) , ( Z m m m i m L P P D 5. 3 Performance Parameters To evaluate the performance of the proposed ISP MBG technique, the following five measuring criteria are measured: Link Distance, Transmission Time, Blocking, Buffering and Security. 5. 3. 1 Link distance The link distance is calculated in kilometers equivalent to the pixels distance between the two connecting nodes through the PoP links or the Agent links (1 pixel = 0.2km). The link distance can be calculated and formulated using the following equation: Dt (Pi, Pz) = Where; P: Transmission point (PoP or MBG) D: Euclidian distance Dt: Total link distance between two transmission points 5. 3. 2 Transmission time Measuring the transmission time depends on the location of both Mobile Node (MN) and Correspondent Node (CN) and whether both are located in the same area, same Internet Service Provider or either in different areas or different Internet Service Providers. The transmission time is calculated and formulated using the following general form of equation: T (Pi, Pz) = Where; P: Transmission point (PoP or MBG) T (Pi, Pz):Total transmission time between two transmission points Pi and Pz L: Link speed D: Euclidian distance 5. 3. 3 Blocking Blocking is an important parameter to measure the overall performance of the network and its throughput. The blocking is measured as the number of blocked connections. Each connection has a pair of connecting nodes, (i.e. N connections = 2N Nodes). 5. 3. 4 Buffering Buffering is considered as one of the network resources that must be optimally used. In the conventional Mobile IP technique, we have storage buffers for the agents whether they are Home Agents or Foreign Agents. In the proposed ISP MBG technique, each PoP has its own storage buffers which hold a limited number of nodes. The nodes are classified as nodes in service and nodes in waiting, with a range of addresses for the nodes that are either locally generated within the Agent (Home addresses) or imported from the other Agents. Using Point of Presence Virtual Network (PVN) will provide an efficient tool for accessing the Node's information between PoPs.[The measuring evaluation of this parameter is out of our scope]. 5. 3. 5 Security
- 15. - - 15 It is one of the rigid requirements for the performance evaluation between the conventional Mobile IP technique and the proposed one. It is measured as how much the technique itself provides a self-securing technique to protect the data transferred among the nodes located in different networks.[The evaluation of this parameter is out of our scope] 5. 4 Simulation Results The purpose of the simulation is to evaluate the performance of the proposed technique using Internet service Providers' PoPs and MBG compared with the conventional Mobile IP technique. The running for the implemented algorithm is done and calculated based on generating randomly a total number of nodes N= 640 nodes in 32 steps, each step includes 20 more nodes (i.e 10 connections). In each step, the whole algorithm is executed, and the connection is also randomly done between each pair of nodes. To obtain real results, the algorithm is executed many times and the comparison is done based on the average values of the results. 5. 4. 1 Simulation results for link distance Figures 12.a and 12.b show the total link distance and the average link distance per connection for both the proposed ISP MBG and the conventional Mobile IP technique respectively. It is clear that the proposed ISP MBG technique outperforms the conventional Mobile IP technique. The route taken by the conventional Mobile IP technique has to pass through the Home Agent which tunnels the data to the Foreign Agent. The route in the proposed ISP MBG technique is taken through the home PoP of CN and the PoP virtual network of MN which leads directly to the MN in case of one ISP. In case of using two Internet service Providers the route has to pass through MBG to the MN's PoP virtual network in the second ISP which leads directly to the MN. At the point where no blocking appears (refer to section 5.3.3 where the number of connections ïŒ 28) the total link distance is increasing and the average link distance per connections is almost constant, as all the entering connections will be served. At the point where the blocking appears (refer to section 5.3.3 where the number of connections â„ 28), the total link distance and the average link distance will be slightly increased. As the rate of blocking increases the total link distance is also increasing. For the case where the system is saturated and due to the random generation of nodes and their connections are added to the simulation, the distribution of nodes becomes more fair and the blocking is slightly decreased which causes the average link distance to be consequently decreased. (a) Comparison between total Link Distances 0 200 400 600 800 1000 1200 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 #of Connections (unit 10) Distanc (km) ISP MBG Conventional Mobile IP
- 16. - - 16 (b) Comparison between Average Link Distances Figure 12. Link Distance Comparison 5. 4. 2 Simulation results for transmission time Figure 13.a and 13.b show the total transmission time and the average transmission time (in seconds) per connection against the number of connections for both the conventional Mobile IP technique and the ISP MBG technique respectively. The figures show a great reduction in the transmission time using the proposed ISP MBG technique, compared with the conventional one. That result is expected because of using PoPs and PVNs: the home information for any node will be available anywhere among the networks and not only restricted on the Home Agents that could be far away from the connecting nodes. At the point where no blocking appears (refer to section 5.3.3 where the number of connections ïŒ 28) the total transmission time is increasing and the average transmission time per connections is almost constant, as all the entering connections will be served. At the point where the blocking appears (refer to section 5.3.3 where number of connections â„ 28) the total transmission time and the average transmission time are slightly increased. As the rate of blocking increases the total transmission time is also increasing. For the case where the system is saturated and due to the random generations of nodes and their connections are added to the simulation, the distribution of nodes becomes more fair and the blocking is slightly decreased which causes the average transmission time to be consequently decreased. (a) Total Transmission Time for the Conventional and Proposed Techniques 0 50000 100000 150000 200000 250000 300000 350000 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 #of Connections ( Unit 10) Total Distnace (km) ISP MBG Conventional Mobile IP 0 1000 2000 3000 4000 5000 6000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 #of Connections ( Unit 10) Total Transmission Time (sec) ISP MBG Conventional Mobile IP
- 17. - - 17 (b) Average Transmission Time for the Conventional and Proposed Techniques Figure 13. Transmission Time Comparison 5. 4. 3 Simulation results for blocking Figure 14 details the average number of blocking in both the conventional Mobile IP technique and the proposed one. Each blocked connection is considered as single pair of connecting nodes. The figure shows that as long as the number of connections ïŒ 28 (i.e. number of nodes ïŒ 560, "560= number of connections {28} x number of generating nodes in each connection {20}") the blocking rate is almost zero in both the conventional mobile IP technique and the proposed ISP MBG technique. If the number of connection is increased (number of connections â„ 28) meaning that the number of nodes is also increased (number of nodes â„ 560) the blocking rate will be increased for both the conventional Mobile IP technique and the proposed one. The number of blocked connections using the newly proposed ISP MBG technique is less than that the conventional Mobile IP technique. In the conventional Mobile IP technique, the HA is overwhelmed with an excessive amount of nodes' control messages compared with the proposed technique in which the control messages are divided among the PoPs. Each PoP covers a number of nodes and the virtual network between PoPs helps in getting the information easily. Figure 14 Blocking Comparison 0 2 4 6 8 10 12 14 16 18 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 #of Connections (unit 10) Transmission Time (sec) ISP MBG Conventional Mobile IP 0 2 4 6 8 10 12 14 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 #of Connections Blocked Connections ISP MBG Conventional Mobile IP
- 18. - - 18 As the number of blocked connections decreased that leads to increase the number of paired successful connections which means the throughput will be increased. 5. 4. 4 Buffering Concerning Buffering; it has been found that the proposed ISP MBG technique provides better buffering than that the Conventional Mobile IP technique. This is due to the fact that using PVN with the proposed technique facilitates the process of handling and accessing information for the nodes in correspondences between PoPs without any redundancy. Comparatively, the conventional technique requires more buffers due to the redundancy of having a multiple copies of nodes' home information at each PoP of the Internet service Provider. This leads to less use of buffering storages than that of the conventional technique which needs storage buffer for each node to hold all of its information at each PoP. Also, as a cost wise, it has been found that the cost for the Agent's buffers is higher than that of the PoP's buffers 5. 4. 5 Security The Security design has a great concern in Mobile IP. The proposed ISP MBG technique is considered as the self securing system. Using Mobile IP Border Gateway (MBG) will keep the information (Home address or binding information) for all Mobile Nodes crossing their network to another network. So, any CN in one network does not need to maintain any private external information concerning the new IP network were the MNs visit and all of the MN's information could be accessed directly so the Mobile Border Gateway. Comparatively, the conventional Mobile IP technique needs rigid requirements for the authentication to prevent the malicious users from interrupting the connection between MN and CN that maintains the binding information (Ha, CoA). 6. Concluding Remarks In this paper, a proposed technique called Internet Service Provider Mobile IP Border Gateway (ISP MBG), has been introduced to solve the Triangle Routing Problem in conventional Mobile IP Protocol. The design of this technique is based on using a number of Internet Service Providers (ISPs) separated by a Multiple Mobile IP Border Gateways (MBGs) which are used to keep the binding information or the home information for the transferred Mobile Nodes between ISPs. Each ISP is composed of an approximately a number of an equal areas, each is served by an Agent and is composed of a multiple equal zones. Each zone is served by a definite number of Points of presences (PoPs). Each PoP is serving a number of nodes with a range of addresses. Virtual Networks are used to connect the PoPs in such a way the redundancy in keeping the nodes information will be minimized or almost cancelled. The main function of the proposed technique is to get the shortest routing path for the packets transferred between the Correspondent Nodes and Mobile Nodes based on the PoPs information, PVN and the MBG. The simulated network design of our case study is based on using two Internet Service Providers separated by one mobile IP border gateway. Each ISP is divided into two equal areas. Each area is divided into two equal zones and each zone is served by four points of presence (PoPs). Each PoP is serving 20 nodes with a range of 30 addresses. The simulation results for the Link Distance, Transmission Time, Blocking, Buffering and Security show that the proposed (ISP MBG) technique outperforms the conventional Mobile IP technique by minimizing the Link Distance, Transmission Time, Blocking, Buffering. Also, it gives a higher level of security than that used with conventional Mobile IP technique.
- 19. - - 19 Table 1 summarizes the performance comparison between the conventional Mobile IP technique and ISP MBG technique. Table 1. Comparative Parameters for the Conventional and Proposed Techniques Technique Parameters ISP MBG Technique Conventional Mobile IP Technique Link Distance Short link distance Long link distance Transmission Time Low transmission time High transmission time Blocking low rate of blocking High rate of blocking Buffering - Less buffering storages - Low cost - More buffering storages - High cost Security High level of security Low level of security The ISP MBG technique is considered to be the best suited technique for the ISPs with larger topographical reach, because of the drastic performance improvement obtained in this case. This work can be considered applicable for the following: better performance related to the criteria of measuring parameters ,no addition of external hardware devices are required, more reliablility and flexibility of the simulation model,and scalability for using more PoPs and nodes . The implemented algorithm could be extendable to any number of ISPs, Areas, Zones, PoPs, Nodes, but the evaluation will be related to the configuration of the system that is used in building up the simulator and how much the behavior of the system is adapted to the measuring parameters. 7. Future Work This work can be extended to include investigation of using multiple ISPs and multiple MBGs. In that case MBG is not only restricted to hold the home information for the nodes crossing their local ISP or to guide in establishing the route to the MN located in an external ISP, but rather the investigated subjects in that area are continuing enhance the functionalities of MBG to do more advanced tasks.Such tasks include, tunneling, conditional Processes for the route optimization, and others .Moreover, using multiple MBGs will distribute the processing load among the MBGs. References 1. C. Smith and D. Collins, â3G Wireless Networksâ, âMcGraw-Hill, United States, 2002. 2. A. Jamalipour, âThe Wireless Mobile Internetâ, John Wiley & Sons Ltd., England, 2003.
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