QoS in Mobile IP by Preethi Tiwari Chaitanya Deshpande
INDEX • RSVP – Resource Reservation Protocol • Problems with RSVP • Effects of Mobility • Requirements of Mobility • Implementation of MRSVP • Conclusion
RSVP – Resource Reservation • This protocol is used to provide real-time services to mobile users. • Can be used to reserve resources along the network path between senders and receivers in order to provide QoS guarantees for a particular application. • RSVP is a receiver initiated resource reservation protocol. • The two most important types of messages in RSVP are : Path and Resv • As the PATH message traverses towards receiver, RSVP-enabled routers on the path will setup the PATH state. Receiver, after receiving the PATH message, sends RESV message back to the sender along the same path traversed by PATH message.
RSVP R2 R1 R5 Sender Receiver 2 R4 R3 PATH RESV Receiver 1
Problems with RSVP • RSVP does not have any provision for passive reservation. • In RSVP, Reservation can be initiated from a location, only when the sender or the receiver is present at that location. • RSVP does not support tunneling.
Effects of Mobility Mobility of a host has a significant impact on these QoS parameters. QoS parameters for real-time services • Packet delay • Packet loss rate • Delay jitter • Throughput Due to the change in the active flow path, the packet delay also changes depending on the packet length and the congestion levels at the routers along the new path. To obtain a QoS which is not affected by mobility, it is necessary to make resource reservation from many locations where the mobile host may visit.
Requirements of Mobility • Fundamental requirement: MN must be able to make advance reservations. • Protocol requires the information such as MSPEC (set of locations from which MN requires reservations). • MRSVP requires two types of reservations: ACTIVEResv and PASSIVEResv • Reservation for a flow on a link is ACTIVE if data packets of that flow are traveling over the link to a receiver. • If resources are reserved for the flow on the link, but actual data packets of the flow are not being transmitted then the reservation is PASSIVE. • Passive Resv are required to become Active Resv whenever there is an active sender or receiver involved in that data flow path.
MRSVP - Implementation • Identify Proxy Agents that will make reservations on behalf of mobile senders and receivers. • The sender periodically generates Active path messages, and for a mobile sender the Proxy Agents will send Passive path messages along the flow path to the destination. • The Proxy Agents for a mobile receiver send the Passive Resv messages while the receiver itself sends the Active Resv messages.
MRSVP Sender 1. Spec 2. PATH 3a 2 3a. Active RESV Router 3b. Passive RESV 3b 3a Router 2 2 Router 2 2 2 3b 3a 3b 1 1 Spec Spec Proxy Proxy Proxy Proxy MN
MRSVP - Handoff Sender Active Reservation Router Passive Reservation Router Router Proxy Proxy Proxy Proxy Handoff MN MN
MRSVP – After Handoff Sender Active Reservation Router Passive Reservation Router Router Proxy Proxy Proxy Proxy MN
Additional Messages required in MRSVP: • Join_group:This message is sent by a mobile receiver to its remote proxy agents to request them to join a multicast group. It contains the multicast address of the group to join. • Receiver_Spec: This message is used by a mobile receiver to send the FLOWSPEC and the flow identification to its remote proxy agents. • Sender_Spec:A mobile sender uses this message to send its SENDER_TSPEC, ADSPEC and the destination address of a flow to a proxy agent. • Receiver_Mspec: This message is used by a mobile host to send its MSPEC to the appropriate node who sets up the routes of active and passive reservations. It contains the addresses of proxy agents of the locations in the MSPEC. • Sender_Mspec: This message is used by a mobile sender to send its MSPEC to a proxy agent, which sets up the routes of active and passive reservations for the mobile sender. • Forward_Mspec: This message is used by a mobile sender to forward the MSPEC of a mobile receiver to its local proxy agent. • Anchor_Spec: This message is used by a sender anchor to forward the flow-specific information to the mobile sender and its proxy agents. • Terminate: This message is used by the mobile host to request its remote proxy agents to terminate reservation.
Limitations of MRSVP • Generates too much control traffic because each MN needs to periodically update its reservation. • Doesn’t Utilize the wireless bandwidth efficiently. • Requires users to know in advance where they want to go.
Conclusion: • MRSVP, or mobile hosts is an Integrated Services Packet Network. • The main feature of this protocol is the ability to make advance reservations for a mobile host at locations where the mobile host may visit with its active flow. • The other important feature of MRSVP is the use of activeand passive reservations to improve the network resourceutilization. • As MRSVP is an extension of the reservation protocol RSVP. Thus MRSVP contains all the functionalities and messages of RSVP.