An SAIC Company

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A. Misra, S.Das, A. McAuley and A. DuttaTelcordia Technologies, USAS.K.DasUniversity of Texas at Arlington, USA

Integrating QoS Support in the Dynamic Mobility Agent (DMA) Architecture

DIMACS Workshop, Feb. 8, 2001,Rutgers, NJ.

DIMACS – 2©Telcordia Technologies Inc., 2001. February 7, 2001

Introduction

Higher bandwidth packet-based technologies are emerging, such as, GPRS, EGPRS and UMTS2000

Next generation cellular networks will not only support users with different bandwidth guarantees but also transport multimedia traffic with diverse QoS constraints

End-to-end QoS guarantees for mobile users are desirable


IP Mobility Management-State of the Art

Solutions such as MIP (Mobile IP) and SIP-based mobility provide basic ubiquitous connectivity.– Use of temporary care-of addresses (CoA) to redirect packets without

modifying the fundamental routing fabric.

Newer solutions such as HAWAII, CIP, MIP-RR and IDMP provide hierarchical mobility management.– Use either specialized host-based routing or multiple CoAs to provide

a more stable CoA to external hosts.

Integration with an IP-level QoS architecture is missing.– Need to provide load-balancing and QoS-assuring features to mobile

nodes (MNs).


Wireline IP QoS Architectures…1

Two wireline-oriented mechanisms for supporting IP-based QoS guarantees.– Integrated Services (Intserv)

Reservation of resources on a per-flow (fine) granularity, with intermediate nodes maintaining reservation state.

– Differentiated Services (Diffserv) Coarser classification at the network edge, followed by class-based

(stateless) differentiation in the core.

Multi-Protocol Level Switching (MPLS) provides the ability to control the path of traffic through an IP network.– Resource reservation is easier when not just the traffic load, but its

path, is well-established. is also emerging as a standard for traffic flows via Internet


Wireline IP QoS Architectures…2

The Bandwidth Broker (BB) architecture has been proposed for dynamic admission control and resource provisioning.– Centralized agent maintains knowledge of the link capacities and link

loads within the domain.– Workable for small-to-medium sized domains.

Little work on architectures that integrate QoS and mobility management in next generation wireless IP networks.Key issue is the need for dynamically signaling the changing load

levels on a path as MNs change their point of attachment.


Overview of the Basic DMA Architecture

During the initial subnet-level configuration process (via DHCP/DRCP or from an SA), MN receives a Local Care-of Address (LCoA) and the address of a Mobility Agent (MA).

The MA associated with this MN remains the same throughout its stay in this domain. The MA provides the MN with a stable globally valid care-of address (GCoA), which ensures global reachability.

Visited Network/Domain

Home Network /Domain

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MA

DHCP/DRCP

MN


Overview of IDMP Our protocol for performing the intra-domain mobility

management (with QoS, of course!).

Two options for getting a GCoA.– Shared GCoA—All MNs assigned to an MA use the MA’s address as their

GCoA. This mandates external tunneling (from the Internet to the MA).– Unique GCoA- MA assigns each MN a unique GCoA from an address pool.

MA is then responsible for intercepting packets addressed to that pool- removes the need for external tunneling.

Provides IP-level support for – Multicasting-based fast handoffs: packets are buffered at the new point of

attachment and are available immediately after subnet-level configuration.– Paging: MA will multicast a solicitation for an idle MN that is still in that

domain.


IDMP Overview (SA Mode)

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MN receives two addresses from Subnet Agent (SA).One is for Local Care-of Address (LCoA) and the other one is MA. On every change in subnet, the MN interacts with the SA to obtain a new LCoA.

SA is responsible for demultiplexing all packets tunneled to SA’s interface address and forwarding them to individual MN using layer-2 mechanisms -> no transmission of tunneled messages on the wireless interface.



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MA

SA

MN


IDMP Overview (CO Mode)

MN receives two addresses from additional subnet level configuration protocols, such as DHCP or DRCP.One is for Local Care-of Address (LCoA) and the other one is the MA’s address.

In this mode MN is responsible for decapsulating packets destined to it -> tunneling over the wireless link. Also, not feasible to provide QoS support with this mode.



CN

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MA

DHCP/DRCP

MN


Message Flow in SA Mode

MN SA MA HA/SIP Server

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Message Flow in CO Mode

MNDHCP/DRCP

Server MA HA/SIP Server

DISCOVER

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The QoS framework of DMA An MN specifies its QoS requirements only during the initial

registration in the domain.– No support yet for subsequent renegotiation of QoS.– QoS profile transferred by MA to the SA at the new point of attachment.

Bandwidth Broker architecture is used to centralize the dynamic management of resources for different service classes.

– As MNs move, the corresponding MA interacts with the BB to set up resources as needed.

DMA splits the end-to-end QoS management into two distinct parts:

– Global QoS framework which uses Diffserv/MPLS framework– Intra-domain QoS framework also based on Diffserv/MPLS.– By providing reservations and guarantees on aggregates, we reduce

the QoS signaling load.


Functional QoS Architecture


Signaling Flow for QoS in IDMP/DMA


Some Additional Considerations

Pre-configuration– For services requiring lower latency in the re-establishment of

QoS guarantees, the MA can perform pre-configuration to neighboring SAs

– MA can preemptively multicast the MN’s traffic and QoS parameters to the set of neighboring SAs

On-Demand– When MN moves from its initial point of attachment within a

domain, the new serving SA must be configured with MN-specific traffic descriptor and conditioner parameters

– MA may need to request the BB to reserve additional resources over the new path


Further Considerations

Admission Control Choices– Network must ensure that adequate bandwidth is available over the

new path in conformance to the specified QoS bounds– Network operator can choose different admission control strategies for

each service class

QoS for Mobile Nodes: We are currently concentrating on two models:

– In simpler model, users are simply distinguished by differential bandwidth guarantees. A single user has a single QoS profile.

– In advanced model, users are distinguished not simply by the negotiated traffic rate, but also by the bounds associated with performance –related metrics, such as, packet jitter or loss. Individual users have multiple QoS profiles.


IDMP Message Extensions

Subnet Registration_Request– Extended to include QoS-specific extensions, such as peak rate and

desired packet delay

Subnet Request_Reply– Extended to allow an SA to specify multiple MA addresses to an MN,

as well as QoS extensions.

Intra-domain Location_Update– Extended to allow an MN to specify the requested QoS parameters

to the candidate MA

Intra-domain Location_Reply– Extended to allow an MA to specify the assigned QoS parameters to

an MN


One Class-per MA Architecture


Multiple GCoA-based QoS Architecture


Single GCoA-based QoS Architecture


Additional QoS-related Considerations

The DMA architecture does not employ dynamic host-based routing.– An MPLS FEC can simply be designed based on the destination

LCoA pool—the LCoAs reflect the subnet of attachment.– In contrast, solutions such as HAWAII or CIP require each

intermediate router to consult its forwarding table. Harder to set up “fast paths” in such an environment.

DMA essentially treats the cellular domain as a separate Diffserv domain.– Use of MPLS with the BB-based mechanism will be explored.– At the very least, the BB approach should be scalable to a “domain”

with O(1000) MNs.


Implementation Status

Basic IDMP functionality implemented and tested in Linux.– Currently uses MIP for global binding.

The BB functions developed and tested as part of separate project.– Communication with BB via CORBA; communication between BB

and routers via rcp.

QoS extensions to IDMP currently being implemented and tested on our testbed.– Main piece of unfinished work is the development of the Mobility

Server (MS).


Conclusion DMA: An architecture for supporting QoS guarantees in next

generation IP-based wireless networks.– IDMP for two-level hierarchical mobility management.– BB-based dynamic resource provisioning for a Diffserv-based cellular

domain.

QoS based on the introduction of new functionality in elements such as the MA and SA, and the specification of the MS.– MN signals QoS profile only on first registration; subsequent negotiation

not needed.– MS implements a dynamic QoS-aware MA assignment algorithm for load

balancing.– Suited to introducing MPLS-based “fast paths” in the cellular domain.

Different MA assignment architectures explored for different QoS-based mobility service scenarios.


Publications

S. Das, A. Misra, P. Agrawal and S. Das, “TeleMIP: Telecommunication Enhanced Mobile IP architecture for Fast Intra-Domain Mobility”, IEEE PCS Magazine, August 2000.

A. Misra, S. Das, A. Mcauley, A. Dutta and S. K. Das, “IDMP: An Intra-Domain Mobility Management Protocol using Mobility Agents”, <draft-misra-mobileip-idmp-00.txt>, Work in Progress, July 2000.

A. Misra, S. Das, A. Mcauley, A Dutta and S. K. Das, “Introducing QoS Support in TeleMIP’s Mobility Architecture”, Proceedings of IEEE International Conference on Personal Wireless Communications, December 2000, Hyderabad.

K. Chakraborty, A. Misra, S. Das, A. Mcauley, A Dutta and S. K. Das, “Implementation and Performance Evaluation of TeleMIP”, to appear in Proceedings of ICC, June 2001, Helsinki.

A. Misra, S. Das, A. Mcauley, A Dutta and S. K. Das, “Supporting Fast Handoffs and Paging in IDMP”, to appear in Proceedings of 3G Wireless 2001 Conference, June 2001, San Francisco.

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