Mobile IP: Quality-of-Service

Reference: “Domain based approach for QoS provisioning in mobile IP”; Ki-Il Kim; Sang-Ha Kim; Proc. IEEE Global Telecommunications Conference (GLOBECOM), 2001; pp. 2230 –2234. (MobileIPQoS-4.pdf)

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ISA Concept• Integrated Services Architecture

– Intended to provide QoS transport support over IP-based internets, RFC 1633

• Two broad categories of traffic on internet– Elastic Traffic

File transfer (FTP) , Email (SMTP), Remote Logon (TELNET), Network management (SNMP), Web access (HTTP)

– Inelastic TrafficReal-time traffic

Throughput, Delay, Jitter, Packet loss

Background

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ISA Approach• Traditional (IP) Router mechanisms

– Routing algorithm

– Packet discard

• ISA Enhancements: the concept of flow– Admission control: RSVP

– Routing algorithm: QoS-based OSPF

– Queuing discipline: For differing requirements of different flow

– Discard policy: for managing congestion and meeting QoS guarantees

Background

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ISA Components

ISA Implemented in RouterBackground

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2-Level ISA Services• 1. General categories of service

– GuaranteedAssured capacity/data rate

Specified upper bound on the queuing delay

No queuing loss

– Controlled Load

– Best effort

• 2. Service for a particular flow

– Traffic specification (TSpec): Token Bucket

– QoSBackground

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Token Bucket Scheme

Background

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Queuing Discipline

Weighted Fair Queuing (WFQ)No priority; Larger mean delayGreedy TCP connections crowd out altruistic ones

Background

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Resource ReSerVation Protocol• Characteristics

– Unicast and Multicast

– Simplex

– Receiver-initiated reservation

– Maintaining soft state in the internet

– Providing different reservation styles

– Transparent operation through non-RSVP routers

– Support for IPv4 and IPv6Type-of-Service in IPv4

Flow Label in IPv6Background

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RSVP Design Characteristics• Receiver-initiated reservation

– SenderProvide the routers with the traffic characteristics of

the transmission (data rate, variability)

– ReceiverSpecify the desired QoS

– RouterAggregate multicast resource reservations for the sh

ared path segments along the distribution tree

• Soft StateBackground

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RSVP Data Flows• Flow descriptor

– flowspec: desired QoS– filterspec: defines the set of packets for the reservation

Treatment of packets of one session at one router

Background

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RSVP Protocol Mechanisms

• Two message types– Resv, Path

Background

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RSVP Operation

Background

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Differentiated Services (DS)

• Goal (RFC 2475)

– Provide a simple, easy-to-implement, low-overhead tool to support a range of network services (comparing with ISA)

• Key characteristics

– IP packets are labeled for differing QoS treatment using the existing IPv4 Type-of-Service octet or IPv6 Traffic Class octet. Thus, no change is required to IP

Background

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Differentiated Service (cont)

– A service level agreement (SLA) is established between the service provider (internet domain) and the customer prior to the use of DS

– All traffic with the same DS octet is treated the same by the network service

– Routers deal with each packet individually and do not have to save state information on packet flows

Background

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DS Octet• Packets are labeled for service handling b

y means of the DS octet

• Placed in the Type of Service field of an IPv4 header, or the Traffic Class field of the IPv6 header

• RFC 2474: The leftmost 6 bits form a DS codepoint

• The DS codepoint is the DS label used to classify packets for differentiated services

Background

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DS Codepoint (6 bits)• xxxxx0

– Reserved for assignment as standards

– 000000: default packet class, i.e. best-effort

– xxx000: reserved to provide backward compatibility with the IPv4 precedence service

• xxxx11– Reserved for experimental or local use

• xxxx01– Reserved for experimental or local use, but

may be allocated for future standards action as needed

Background

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DS Domain• Within a domain, the interpretation of DS codepoints

is uniform, consistent service is provided

Background

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Routers in DS Domain• Interior nodes (per-hop behavior: PHB)

– Queuing discipline to give preferential treatment depending on codepoint value

– Packet-dropping rules to dictate which packets should be dropped first in the event of buffer saturation

• Boundary nodes

– PHB mechanisms

– Traffic conditioning functionsmetering, marking, shaping, dropping

Background

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DS Traffic Conditioner

Background

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DS Traffic Conditioner (cont)• Classifier

– Separates submitted packets into different classes

– Based on the DS codepoint or on multiple fields within the packet header

• Meter– Measures submitted traffic for conformance to

a profile

– Determines whether a given packet stream class is within or exceeds the service level guaranteed for that class

Background

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DS Traffic Conditioner (cont)• Marker

– Polices traffic by re-marking packets with a different codepoint as needed

• Shaper– Polices traffic by delaying packets as necessar

y so that the packet stream in a given class does not exceed the traffic rate specified in the profile for that class

• Dropper– Drops packets when the rate of packets of a gi

ven class exceeds that specified in the profile for that class

Background

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ISA (IntServ) vs. DS (DiffServ)

Background

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Introduction• Tunneling mechanism in MIP causes serious

problems in adapting to the Internet QoS architecture

– Integrated Service and Differentiated Service

– IntServ and DiffServ Identify the end-to-end service session by address field of IP header and port field of transport layer header

– Different sessions over tunneling section must be defined

– Mapping the new section over IP tunnel to the end-to-end service session must be defined

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Related Work• 1. New RSVP session over IP tunneling se

ction is created and is mapped to the end-to-end RSVP session using IntServ semantics

– Scalability problem remains

– As the number of mobile host is increased, the session information per flow must be maintained

– Implementation difficulties on existing network

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Related Work (cont)• 2. The edge router located on the tunneling

entry point remarks the DSCP in the IP header to reflect settled service level agreement

– DSCP: Differentiated Service Code Point

– Only qualitative QoS can be guaranteed, quantitative QoS may not be guaranteed sometimes

– Implementation difficulties on existing network

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Related Work (cont)• 3. The entire RSVP requests are aggregated

over tunneling

– Additional control message and state information is needed (compared to the 2nd mechanism)

– Be able to guarantee not only quantitative QoS but also qualitative QoS

– Flow aggregation makes the number of the state information small, the scalability problem can be removed

– The paper is based on this mechanism

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Two types of Mobility

• Micro mobility

• Macro mobility

– MIP

• The authors proposed the macro level QoS guarantee mechanism

– The domain level agents and aggregate RSVP signaling between them are defined for the macro level QoS

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Two issues on MIP QoS• 1. How to guarantee QoS over a tunneling

section?

– Ref. [3]: The tunneling section is defined as the new RSVP session from the ingress point to the egress point

– Ref. [4] (based on [3]): The mobile host moves to another FA. The HA sends the new RSVP Path message to the FA in order to create the new RSVP session over IP tunnel when the periodical RSVP Update message arrived

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Two issues on MIP QoS (cont)

• 2. How to guarantee seamless real-time service regardless of handoff of a mobile host?

– MRSVP (Ref. [5]): To minimize the effect of host mobility, MRSVP reserve resources in advance according to expected location, where mobile hosts is expected to move

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Example Configuration

Gateway router

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Proposed Mechanism• At least one aggregate RSVP session

must be created between the gateway routers– One gateway router must maintain the state

information as many as at least the number of border gateway routersSince the domain number is limited as a constant

number, the scalability problem does not occur

– The small flows, which come from the access network, must be mapped to several aggregate flows between gatewaysDomain agent performs the functionality of

aggregating router or de-aggregating router

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Proposed Mechanism (cont)• In order to guarantee QoS for mobile hosts

– Each aggregated RSVP session between each domain level agent reserves more bandwidth () than the bandwidth actually being used now for the further use

– Each HA checks periodically the bandwidth amount of . If is lower than the initial amount, the HA can detect that the new mobile host moves within its own domain and the previously reserved bandwidth is used. Then the HA sends the RSVP Path message to the FA in order to reserve the bandwidth as much as the currently used bandwidth +

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Dealing with mobility

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Micro Level QoS

• 1. Applying the RSVP

– The end-to-end RSVP session consists of several RSVP sessions

From the sender to HA

From HA to FA

From FA to mobile host

– See the figure on next slide

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Applying the RSVP in micro level

Individual Path/Resv Aggregate Path/Resv Individual Path/Resv

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Micro Level QoS (cont)

• 2. Applying the DiffServ in Micro level QoS

– The FA must decide the DSCP according the QoS requirement received in the registration request message

– The FA must perform the functionality of Bandwidth Broker (BB) in DiffServ

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Feature Comparison

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Simulation Topology

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Simulation Parameters

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Simulation Result: Uncontrolled

flow5

flow3flow2

flow4

flow1

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Simulation Result: Proposed

flow5

flow2 flow3 flow1

flow4

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Simulation Result: Comparison

flow5 Delay_flow5

flow1

flow4

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Conclusion

• Proposed scheme

– Macro level QoS

– Aggregation of RSVP flow

– Reserve more bandwidth in advance