Policy-Based QoS Policy-Based QoS Management Management

Architecture in an Architecture in an Integrated UMTS and Integrated UMTS and WLAN EnvironmentWLAN Environment

莊勝超　洪志宗　張永伸　蘇芳生莊勝超　洪志宗　張永伸　蘇芳生IEEE Communications IEEE Communications

Magazine November 2003 Magazine November 2003 p.118p.118

OutlineOutline

IntroductionIntroduction Policy-Based QoS architecture in Policy-Based QoS architecture in

WLAN NetworksWLAN Networks Policy-Based QoS management in an Policy-Based QoS management in an

integrated environment (Scenarios)integrated environment (Scenarios) ConclusionConclusion

IntroductionIntroduction

Why integrate WLAN and UMTS Why integrate WLAN and UMTS network?network?– UMTS ’s bandwidth is not sufficient for UMTS ’s bandwidth is not sufficient for

public wireless broadband servicepublic wireless broadband service– WLAN acts as an complementary WLAN acts as an complementary

broadband access in hotspotsbroadband access in hotspots What is the benefit for integrating WLAN What is the benefit for integrating WLAN

and UMTS network?and UMTS network?– High bandwidth for hotspot and seamless High bandwidth for hotspot and seamless

coverage for other placecoverage for other place

Introduction (cont.)Introduction (cont.)

QoS (QoS (QQuality uality oof f SService)ervice)– QoS is an industry-wide initiative to provide QoS is an industry-wide initiative to provide

preferential treatment to certain subsets of data, preferential treatment to certain subsets of data, enabling that data to traverse the Internet or enabling that data to traverse the Internet or intranet with higher quality transmission serviceintranet with higher quality transmission service

Policy-basedPolicy-based– Policy-based management is an administrative Policy-based management is an administrative

approach that is used to simplify the approach that is used to simplify the management of a given endeavor by establishing management of a given endeavor by establishing policies to deal with situations that are likely to policies to deal with situations that are likely to occur occur

Introduction (cont.)Introduction (cont.)

PDF/PDP (PDF/PDP (PPolicy olicy DDecision ecision FFunction/unction/PPoint)oint)– MPDF (MPDF (MMaster aster PDFPDF))

PEP (PEP (PPolicy olicy EEnforcement nforcement PPoint)oint) COPS (COPS (CCommon ommon OOpen pen PPolicy olicy SService)ervice)

Policy-based QoS architecture Policy-based QoS architecture in WLAN (cont.)in WLAN (cont.)

Tightly CoupledTightly Coupled– WLAN devices is treated as if they are WLAN devices is treated as if they are

normal UMTS UE (User Equipment)normal UMTS UE (User Equipment)– PDF can enforce the network-level PDF can enforce the network-level

policies at the WR directlypolicies at the WR directly– PDF is reused (WLAN and UMTS)PDF is reused (WLAN and UMTS)– No effect on the 3GPP access control No effect on the 3GPP access control

and billing/charging entitiesand billing/charging entities

Policy-based QoS architecture Policy-based QoS architecture in WLAN (cont.)in WLAN (cont.)

Loosely CoupledLoosely Coupled– WLAN is considered as a peer UMTS WLAN is considered as a peer UMTS

networknetwork– Constitutes a distinct policy domain with Constitutes a distinct policy domain with

its own PDF (WPDF)its own PDF (WPDF)– Standalone WPDF to perform service-level Standalone WPDF to perform service-level

policy control for the WLAN domainpolicy control for the WLAN domain– Is not expected to affect the access Is not expected to affect the access

control and billing/charging reference control and billing/charging reference modelmodel

Policy-based QoS architecture Policy-based QoS architecture in WLANin WLAN

QoS Management in an QoS Management in an integrated UMTS and WLAN integrated UMTS and WLAN

environmentenvironment One operator controls the UMTS One operator controls the UMTS

network and WLANSnetwork and WLANS Different UMTS operators share a Different UMTS operators share a

WLANWLAN An independent WLAN is An independent WLAN is

interconnected to a UMTS operator’s interconnected to a UMTS operator’s networknetwork

Scenario 1: UMTS and WLAN Scenario 1: UMTS and WLAN under one operatorunder one operator

Scenario 1Scenario 1

Scenario 1 (cont.)Scenario 1 (cont.)

When encountered a conflictWhen encountered a conflict– WPDF asks the MPDF to resolve the policy WPDF asks the MPDF to resolve the policy

conflict (by sending QoS parameters)conflict (by sending QoS parameters)– MPDF resolves conflicts by creating new MPDF resolves conflicts by creating new

network-level policies based on the network-level policies based on the network-wide policiesnetwork-wide policies

After resolved the conflictAfter resolved the conflict– MPDF validate new policy with UMTS’ PDFMPDF validate new policy with UMTS’ PDF– Sends back new policy to WPDF and also Sends back new policy to WPDF and also

writes to policy repositorywrites to policy repository

Scenario 2: A WLAN network Scenario 2: A WLAN network shared by multiple operatorsshared by multiple operators

Scenario 2 (cont.)Scenario 2 (cont.)

WPDF is a child node in the policy WPDF is a child node in the policy hierarchies of operators A’s and B’s hierarchies of operators A’s and B’s networksnetworks

It is serving two MPDFs that are It is serving two MPDFs that are peers.peers.

Scenario 2 (cont.)Scenario 2 (cont.)

It is inevitable that the WPDF will It is inevitable that the WPDF will encounter conflict policies provided by encounter conflict policies provided by differentdifferent MPDFs MPDFs

Way of resolving conflictsWay of resolving conflicts– MPDFs soles responsible for negotiating MPDFs soles responsible for negotiating

new policies that will replace the old new policies that will replace the old policiespolicies

– Additional policies known as overriding Additional policies known as overriding policies are preset in the WPDF and are policies are preset in the WPDF and are used to resolve the conflicting policiesused to resolve the conflicting policies

The reason why solution 2 is The reason why solution 2 is betterbetter

Operators of MPDFs does not have to Operators of MPDFs does not have to worry about policies in shared WLAN worry about policies in shared WLAN infrastructureinfrastructure

New WLAN domains can easily be New WLAN domains can easily be added without affecting policies added without affecting policies implemented by the individual implemented by the individual MPDFsMPDFs

Scenario 2 (cont.)Scenario 2 (cont.)

Scenario 2 (cont.)Scenario 2 (cont.)

When encountered conflictsWhen encountered conflicts– First, WPDF must verify that they do not First, WPDF must verify that they do not

conflict with policies installed by conflict with policies installed by anotheranother MPDFMPDF

– Second, WPDF asks the MPDF to resolve Second, WPDF asks the MPDF to resolve the conflicts by sending QoS parametersthe conflicts by sending QoS parameters

Scenario 2 (cont.)Scenario 2 (cont.)

If there is a conflict between QoS If there is a conflict between QoS parameters and policies installed by parameters and policies installed by anotheranother MPDF MPDF– WPDF resolve the conflict by applying WPDF resolve the conflict by applying

overriding policies (modify QoS overriding policies (modify QoS parameters)parameters)

– Send overriding policies to MPDFSend overriding policies to MPDF After MPDF creating new policyAfter MPDF creating new policy

– MPDF validates them with PDF of the UMTS MPDF validates them with PDF of the UMTS domain on the data path of the sessiondomain on the data path of the session

Scenario 3: Customers’s WLAN Scenario 3: Customers’s WLAN Interconnected to an Interconnected to an

operator’s UMTS networkoperator’s UMTS network

Scenario 3 (cont.)Scenario 3 (cont.)

This model allows the UMTS operator This model allows the UMTS operator to provide wide-area mobile services to provide wide-area mobile services to customers that have their own to customers that have their own WLAN infrastructureWLAN infrastructure

WPDF in the WLAN domain is a peer WPDF in the WLAN domain is a peer of the MPDF in the UMTS networkof the MPDF in the UMTS network

Network-level policies is determined Network-level policies is determined by service level specifications (SLSs)by service level specifications (SLSs)

Scenario 3 (cont.)Scenario 3 (cont.)

There are dynamic and static service There are dynamic and static service requirementsrequirements– Static service can be directly translated Static service can be directly translated

into enforceable netowrk level policiesinto enforceable netowrk level policies– Dynamic services are dependent on the Dynamic services are dependent on the

state of the UMTS/WLAN networkstate of the UMTS/WLAN network– Dynamic services can only be translated Dynamic services can only be translated

into network-level policies after into network-level policies after negotiating with the connecting networksnegotiating with the connecting networks

Scenario 3 (cont.)Scenario 3 (cont.)

Scenario 3 (cont.)Scenario 3 (cont.) When encounter a network state When encounter a network state

changechange– WLAN send revised SLS parameter WLAN send revised SLS parameter

encapsulated in COPS) to IPA2encapsulated in COPS) to IPA2– IPA2 check if the requested SLS parameters IPA2 check if the requested SLS parameters

is supportableis supportable If supportable, return a positive COPS messageIf supportable, return a positive COPS message If not supportable, forward SLS parameters to If not supportable, forward SLS parameters to

IPA3 after translate into network-level policies IPA3 after translate into network-level policies for verification purposefor verification purpose

If translate failed, return negative COPS If translate failed, return negative COPS decision message to WLANdecision message to WLAN

Scenario 3 (cont.)Scenario 3 (cont.)

ContinuedContinued– IPA3 will repeat IPA2's actionIPA3 will repeat IPA2's action– If updated SLS parameters can be If updated SLS parameters can be

implemented, IPA3 will return a positive implemented, IPA3 will return a positive COPS message, or it will return a COPS message, or it will return a negative COPS message to IPA2negative COPS message to IPA2

– After IPA2 received positive COPS After IPA2 received positive COPS message, it will also return a positive message, it will also return a positive COPS message to WLANCOPS message to WLAN

Scenario 3 (cont.)Scenario 3 (cont.)

If WPDF receieved a negative COPS If WPDF receieved a negative COPS messagemessage– Modify SLS parameters and resend itModify SLS parameters and resend it– Retry until a upper limitRetry until a upper limit

ConclusionConclusion

TodosTodos– Standarlize COPS messageStandarlize COPS message– Enhance security of communications Enhance security of communications

channel between the interconnected policy channel between the interconnected policy entitiesentities

– Quicken the process of policy negotiation in Quicken the process of policy negotiation in peering architecturepeering architecture

ProblemProblem– Depth of the hierarchical architecture Depth of the hierarchical architecture

affects the policy provisioning time in an affects the policy provisioning time in an operator's networkoperator's network