Research On Quality Of Service In Mobile IPv6 Environment Based On RSVP Protocol

With the rapid development of mobile IP technology and large number of applications for mobile devices, mobile users wish to maintain the Internet access and continuous communications when moving, and get the same quality as access to fixed network services; On the other hand, real-time operation are increasing rapidly, it is sensitive to the network bandwidth, delay and delay jitter, require stable transmission services of the network. The existing IPv4 protocol will be replaced by the IPv6 protocol which is formulated to solve the problem of the global shortage of IP address, Mobile IPv6 protocol, which can make full use of IPv6 support for mobility, is highly concerned for its unique advantages. Therefore, how to realize Quality of Service in mobile IPv6 network is one of the hot issues in the current.Currently, there are two kinds of IP network technology to provide QoS guarantees, Integrated Services and Differentiated Service. Differentiated Service is mostly used to distinguish stream and it can allocate network resources according to the different priorities which are endued by the data stream classification. Integrated Services, however, is used for single stream that distributes resources for each data stream based on business needs to realize end-to-end QoS guarantee. Resource Reservation Protocol designed for Integrated Services, is a signaling protocol which chooses data path by lower-level routing protocol and reserves resource along this path. RSVP protocol has good stability and flexibility, and supports different kinds of reservations. The existing Quality of Service of mobile IPv6 is based on the RSVP protocol.Compared with the widely used IPv4 mobile technology,the mobile IPv6 possesses many advantages, such as the sharp increase of IP address, the equal communications from end to end, the automatic address configuration. Moreover, the mobile IPv6 includes the support for Quality of Service and the header of IPv6 contains the Flow Label domain that is a field of 20 bit. Flow Label implemented the concept of flow, A Flow is a sequence of packets sent from a particular source to a particular (unicast or multicast) destination for which the source desires special handling by the intervening routers. The Flow Label is placed at the sender template objects of PATH message and the filter spec object of RESV message, which can achieve a more efficient packet classification.The thesis introduces the process of RSVP in the mobile IPv6 environment in detail, the RSVP protocol is designed for fixed network at beginning. Therefore, there are some defects in mobile IPv6 environment: first, it needs the end-to-end re-consultations and re-establishment of a new resource reservation and it causes long time-delay when Mobile nodes move; second, it has overlapped reservations between the old paths and the new ones, which will result in a waste of resources; third, it lacks of effective congestion control mechanism. Although a series of extended research of RSVP protocol has been made, the problems existing in the mobile environment are only partly solved.Based on the detailed analysis of the mobile IPv6 technology, RSVP protocol and the previous research in this field, the thesis proposes the QoS guarantee model of NRSVP。Firstly, The New Resource Reservation Protocol (NRSVP) that can quickly differentiate and uniquely identify the RSVP session is proposed in this thesis. In the standard Resource Reservation Protocol, a RSVP session is identified by the triple (DestAddress, ProtocolId, DestPort). In the mobile IP environment, the DestAddress field of the mobile node is filled with its care-of address, thus when the mobile node moves and gets a new care-of address, the identifier will be changed, so even the RSVP session that meets the requirements exists in the path, it can not be reused. The Flow Label is appended to the SESSION object and a cache table that can differentiate RSVP session by identifier, is set up on the router in the NRSVP. In this way, the NRSVP can uniquely identify the RSVP session and quickly differentiate the RSVP session that meets the requirements Secondly, the thesis proposes a method of combining the process of binding and NRSVP resource reservation, and introduces the process of the re-reservation in detail. In the mobile IPv6 environment, the route optimization is a necessary option, and the re-reservation in the mobile IPv6 and RSVP happens after the route optimization; On the other hand, the reserved resources on the old path will continue to exist until soft status get overtime after the location switching of the mobile node. And most of the old and new paths are overlapped, which indicates that there are reusable resources on the old and the new path. The NRSVP message is appended to the IPv6 binding message as the Hop-by-hop routing options, and the"SR"field is added in the Binding Update message header in order to support the NRSVP. The type of the NRSVP option is defined, The routers on the way receive the integrated message, and process the NRSVP option in the message. Before setting up the RSVP session, the router will look up the identifier cache table for the existing RSVP session that meets the requirements. If anything is found, the router refreshes the state of existence, otherwise, the router will set up the corresponding status of the reserve requirements. The whole process of binding and reservation implements the utilization of the old and the new duplicate reserved resources, avoids waste of resource, enhances the probability of successful re-reservation, and accelerates the pace of re-reservation.Thirdly, the thesis designs the packet abandoning mechanism based on priority classification. In the case of network congestion, RSVP protocol adopts the strategy of random packet loss which may discard some very important data, which is inconsistent with the requirements of QoS. While the mechanism allows receivers to get better quality of service according to first drop the data of lower priority. The packets of high level will be reserved.Finally, the thesis theoretically analyzes the time of re-reservation between NRSVP and RSVP, and the resource reservation environment is set up by using multiple computers in the laboratory of the local network, the experiment tests and compares the re-establishing time of the resource reservation between the standard RSVP and NRSVP. The data of the experiment proves the result of theoretical analysis, the results prove the feasible and efficient of the NRSVP model.QoS guarantee model of NRSVP implements the utilization of the old and the new duplicate reserved resources, avoids waste of resource, enhances the probability of successful re-reservation, accelerates the pace of re-reservation , effectively guarantes the QoS of the important packet, and enhances QoS levels of the mobile IPv6 network.