Inter-Domain Diffserv Dynamic Provisioning and Interconnection Peering Study using Bandwidth Management Point -- A Simulation Evaluation. Junseok Hwang*, Rajesh Revuru {
[email protected],
[email protected]} School of Information Studies Syracuse University Syracuse, NY- 13244 Keywords: Bandwidth Market,Differentiated Services, Bandwidth Broker, Dynamic Resource Management.
In Diffserv architecture, proposed by Bernet et al [3], the assigned class of traffic at the edge of the network will define the per-domain-behavior (PDB) and associated per hop-behavior (PHB), which in turn will define the ways to treat each packet for each router on the route. Various forms have been proposed for standardized PHBs to define the QoS service category of the DiffServ network. The Default Forwarding (DF) PHB is the most common best-effort forwarding behavior available in the current Internet. The Assured Forwarding (AF)[3] PHB group provides delivery of packets in four independent forwarding classes and assigns three different levels of drop preferences in each forwarding class. The Expedited Forwarding (EF) [4] PHB group can be used for the services requiring a low loss, low jitter, and assured bandwidth within DiffServ network. Host networks set up Service Level Agreements (SLA) with the service provider, where they agree on such a rate of Diffserv traffic that the host network can inject into the Internet. Service providers will forward Diffserv packets according to the SLA characterized by DSCP marking. Service providers will engineer their network so that pure Diffserv traffic cannot face congestion and will set up SLAs with adjacent networks thus enabling end-to-end QoS for Diffserv traffic. The interconnecting networks negotiate SLA with respect to the services to be provided at the network boundary. The subset of SLA that provides the technical specifications such as QoS, aggregate traffic profile, and PHB resource allocation is referred to as the Service Level Specification (SLS) [3]. An SLA and SLS can be static or dynamic. Static SLS’s are negotiated on a long-term regular basis (monthly-yearly). Dynamic SLS implementation requires a network aware middleware agent, and capable of signaling to update the interconnection SLS dynamically (by minute or hour). The purpose of this paper is to present a middleware agent, Bandwidth Management Point (BMP), which is responsible for ensuring effective and economic resource allocation and for provisioning within Diffserv domain and with other domains.
Abstract Dynamic resource allocation with scalable reservation mechanisms is an important challenge for the current Differentiated Services (Diffserv) architecture. In this paper, we present scalable and dynamic resource allocation architecture for Diffserv, which manages the domains network resources. We present agent based network-centric middleware component Bandwidth Management Point (BMP), which will manage the network domain resources efficiently using the SIBBS protocol. We manage the domain resources to: (1) improve the utilization of the bandwidth in the differentiated services domain and (2) reduce the random early packet drops in the Diffserv domain while maintaining scalability characteristics. In this paper, our simulation compares the performance of the Diffserv domain without BMP and with BMP. We find that the BMP will enhance the performance of the Diffserv architecture using the dynamic resource request and resource allocation mechanisms. 1 INTRODUCTION Internet protocol (IP) has undergone significant changes to support the real-time applications.These applications require certain Quality of Service (QoS) guarantees. There has been tremendous interest in engineering the Internet Protocol to provide end-to-end QoS support for innovative applications. Providing some form of end-to-end service differentiation in the Internet has been an important research issue and creates various on-going challenges to support end-to-end QoS in the Internet. The differentiated service (Diffserv) architecture [1] was proposed as a more scalable solution to the end-to-end QoS problem, compared to previous approaches such as integrated services (Intserv) architecture [2]. _________________________ *Corresponding Author:Dr.Junseok Hwang, Assistant Professor,Tel) 315443-4473 Fax)315-443-5806.
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2 BACKGROUND AND RELATED WORK
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Many research proposals were done in solving above stated dynamic resource management issue in the Diffserv architecture. An agent-based architecture, Bandwidth Broker, was first introduced by van Jacobson at el [5]. Based on the bandwidth broker [6,7] approach, some interesting ideas [8,9], are proposed. These proposals address the issues of resource management without any resource request mechanisms from the end user/domain. Terzis et al [10] pioneered on implementing Bandwidth Broker architecture, and their architecture supports EF traffic. Inter-Domain resource provisioning is handled through SLAs. Intra-Domain communication is carried over by COPS-PR [11]. GARA Globus Architecture for Reservation and Allocation (GARA) [12] facilitates the resource management and allocation process for Globus Grid environments. This architecture contains co-allocator agents that organize the allocation of resources simultaneously on different sites. Different resource brokers contain up-to-date information about the resources of subject and Information Service keeps the current resource information. We present a scheme based on Bandwidth Management Point (BMP) [13,14,15] to solve the dynamic resource request and resource allocation problem with emphasis on end-to-end QoS support. Our model has multiple advantages and superiorities over other architectures. We achieve end-to-end QoS support with appropriate signaling between Intra, and Inter-Domains. We use COPS-PR for Intra-Domain signaling and communication, and SIBBS [16] for Inter-Domain resource provision mechanisms.This agent allocates and controls the bandwidth share between interconnecting networks and DSCP service classes. The BMP of each domain is responsible for intra-domain and inter-domain dynamic resource provisioning and control management. The key aspect of the model is that the BMP makes destination-based SLAs with its downstream domains BMP according to the aggregated traffic demand from its customers, and then dynamically modifies SLA when there is a substantial change in the traffic rate. This scheme obtains optimum resource utilization while avoiding signaling scalability problems in the network core.
Bandwidth Management Point, Inter-BMP communication, Intra-BMP communication 3.1.1 Bandwidth Management Point A Bandwidth Management Point (BMP) is the integral part of our system architecture. The BMP allocates and controls the bandwidth share between different interconnecting networks and serving DSCP service classes. The Bandwidth Management Point (BMP) calculates current service demands, and available network resources, and their values. Using such measures, the BMP makes a decision or sets a policy for admission control, network resource provisioning, SLS (Service Level Specification) configuration, and bandwidth exchange. Figure 1 shows the BMP architecture, which is comprised of the logical entity, BMP, residing in each diffserv domain. Each BMP will be responsible for its corresponding domain resources. Diffserv domain resources include the Ingress, Egress and Core routers. Bandwidth Management Points (PerformAdmissioncontrol,reserveandallocate networkresources,configurecoreandedge routers)
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Figure 1: BMP Architecture BMP is comprised of the following databases, which it uses to make an intelligent decision regarding resource management.The Resources Database keeps the information about the available inter-domain link capacities. BMP uses this information to decide whether there are enough inter-domain resources to support the requested type of traffic on certain inter-domain link. The Edge Routers Database is used for determining the next hop BMP and the next hop network when BMP selects the edge router to forward the traffic.The Paths Database stores the resources of the intra-domain links. BMP consults this table to find out an intra-domain path to a request and updates this table whenever an allocation occurs. The Reservation Database keeps the current active reservations. Information stored includes the capacity of the reservation, start time and end-time of the reservation,source domain,and destination domain where the reservation request sinks.
3 BANDWIDTH MANAGEMENT POINT ARCHITECTURE In this section the overall architecture will be described and the BMP, in particular, will be examined. 3.1 Architectural Principles The proposed architecture aims to provide management mechanisms for (i) multi-class QoS support, (ii) dynamic provisioning, (iii) efficient aggregation, (iv) end-to-end QoS support, (v) scalable management, and (vi) inter-domain QoS traffic engineering. It consists of three functional areas:
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BMP
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The SLA Database contains information for BMP to authenticate the users that sends a request to BMP, authenticated users must be able to access certain resources and be able to ask for certain QoS resources.The Tunnels Database stores the current tunnels established to different domains. BMP supports both micro-flow reservations and aggregated reservations. In the case of aggregated reservations, BMP allocates a tunnel to a destination and aggregates the requests to that destination in that tunnel
utilizes sub-modules corresponding to different service class types. EF policy sub-module will process EF service requests; AF policy sub-module performs AF service provisioning. Database Module is responsible for network resource information storage. Database module spends different databases for edge resource information, resource information, and reservation information. Edge resource information includes available edge router interfaces, with their total capacities, used capacities, and available capacities. It also stores capacities pertinent to service types, for example, EF bandwidth used, EF bandwidth available. Reservation information includes reservation request made from source, to destination, capacity requested, request granted, and duration of request. Peer-BMP module is instantiated by native BMP module, in order to check resource availability downstream. Peer-BMP module does formulation of resource requests into SIBBS message and sends out to downstream BMP.
3.1.2 Inter-BMP Communication We design BMP to interact with BMP’s of neighboring domain to exchange information pertaining inter-domain resources and to establish end-to-end reservation requests. Inter-domain resource provisioning is achieved by the interaction of BMP’s through Simple Inter domain Bandwidth Broker Signaling (SIBBS) protocol [16]. SIBBS provides a flexible mechanism for aggregating signaling messages among the domains. This facility is called virtual peering, it establishes a peering relationship between the bandwidth brokers of non-adjacent network clouds. Message takedown is accomplished via an RAR/RAA pair. An RAR message is used to format the request, and is transmitted across the domains. An RAA message is used to acknowledge the request message. Based upon the availability of resources, the RAA message field varies. CANCEL message format is used to cancel the resource request, which has been placed. CANCEL message can also be used to terminate the current session. REFRESH message is used to refresh the existing request message. A KEEP ALIVE message is used to check the BMP state.
4.1 Experimental Evaluation We have evaluated Bandwidth Management Point (BMP) with a range of experiments, which will put BMP into action and thus evaluate the performance change in diffserv architecture. We have used both EF, AF, DF traffic to study the performance. We define the following parameters: CIR, PIR, CBS and Rate. CIR is the chief or average rate of data transfer. PIR is the peak rate at which the source can transfer at any point in time and is used by the diffserv-enabled router to monitor EF flows. CBS is the committed bucket size used by diffserv-enabled router to monitor AF flows. Rate is data bit rate (bits per second or bps) transmitted by the source on the network. Packet Drops is sum of early drops and Late drops. Early drops follow RED algorithm [20] while late drops occur on account of exceeding queue buffer size. We allocate 1/3rd bandwidth to EF flows, 5/12th bandwidth to AF flows and the rest (1/4th) to best effort.
3.1.3 Intra-BMP communication Intra-domain communication is composed of user application communications and BMP-device communication. Each of these communications requires different objects to carry since they are used for different purposes. Bandwidth requests can be exchanged through signaling protocol such as SIBBS between users and networks. BMP can communicate with network devices through standard protocol called COPS[17], which allows service Request, Decision and Report messages. In summary, BMP architecture can be used as a model to support dynamic resource request and resource allocation mechanisms.
4.2 Topology Figure 2 shows the topology, which we have used for our simulation study. S0
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4 SIMULATION SETUP We evaluate our model by simulation using the ns-2 simulator [18] with the Diffserv module provided by Sean Murphy [19]. Then we developed BMP extensions for ns-2. Bandwidth Management Point Extensions for ns-2 comprise of three modules Policy Manager Module, Database Module, and peer-BMP Module. Policy Manager Module is responsible for employing policy decisions based on the resource requests it receives. Policy manager module
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Figure 2 : Simulation Setup S0 is source, which generates the AF traffic, which is characterized by its code Point 20. S1 is a source, which generates the EF traffic, which is characterized by its code point 10. Links connecting the sources to the origin domain are with a link capacity of 5 Mbps, and delay of 5ms. These
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links use Drop Tail queue management. Link from origin domain to transit domain is of capacity 5 Mbps and with a delay of 5ms. This link uses RED queue management Link from transit domain to destination domain is of capacity 5Mbps and with a delay of 5ms. We characterized this link as the bottleneck link, which will have congestion. This link also uses RED queue management.
Experiment 2 was performed in the lines of experiment 1 but with the involvement of BMP. Figure 4(a) shows the traffic pattern of source S1, which was in-profile (R1≤C1).
4.3 Results Different test scenarios are designed to test the BMP performance with all possibilities, and analysis of results is also explained as follows. The main interest of tests is to monitor the performance of BMP under over provisioning scenarios. We also studied the performance of the differentiated services architecture with BMP and without BMP under and over-provisioning scenarios. Our results are in accordance with theoretical expectations.
Figure 4 a: S1 in-profile with BMP management. Figure 4(b) shows the traffic pattern of source S0 generating at rate, which was out-of-profile (R0>C0). In this figure we can conclude that, BMP was able to allocate bandwidth by re-configuring the policy database, according to the availability of bandwidth end-to-end. This was done by SIBBS message exchange among the peer-BMP.
Experiment 1:S0 out-of-Profile and S1 in-profile without BMP management Experiment 1 was performed with S0 generating traffic at a rate, which was out-of-profile, and S1 in-profile. The profile in this context refers to the policy confined to service level agreement. S0 generates traffic at a rate (R0 ) = 3Mbps(R0). It has CIR (C0)=2Mbps,CBS=1KB. S1 generates traffic to destination at a rate (R1) = 2Mbps, and it has a CIR (C1)= 2Mbps,CBS =1KB. Figure 3(a) shows traffic pattern, for the source S0 with a rate under the profile (R0≤C0), where the total packets and transmitted packets are directly proportional.
Figure 4 b: S0 out-of-profile with BMP management Experiment 3: S0 in-profile and S1 out-of-profile without BMP Management Experiment 3 was performed with S0 in-profile, and S0 out-of-profile.S0 generates traffic at a rate(R0)= 2Mbps.It has CIR (C0)= 2Mbps, CBS =1KB, S1 generates traffic to destination at a rate (R1) =3Mbps, CIR (C1)= 2Mbps, CBS=1KB.Figure 5(a) shows traffic pattern, for the source S1 with a rate under the profile (R1≤C1).
Figure 3 a: S0 out-of-profile with CP 20 Figure 3(b) shows the traffic pattern when the rate exceeds the profile (R0>C0) will be in-proportionately dropped, because of the reason, it has crossed the CIR, and all the drops will early drops.
Figure 5 a: S1 out-of-profile without BMP Figure 5(b) shows the traffic pattern when the rate exceeds the profile (R1>C1) with degradation in code point and with more packet drops. This experiment was done without the BMP involvement.
Figure 3 b: S0 out-of-profile with CP 21 Experiment 2: S0 out-of-Profile and S1 in-profile with BMP management.
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Figure 5 b: S1 out-of-profile without BMP
Figure 7 a: S1out-of-profile without BMP
Experiment 4: S0 in-profile and S1 out-of-profile with BMP Management Experiment 4 was performed in the lines of experiment 3 but with the involvement of BMP. All the sources before sending the data will place a request via SIBBS message with BMP. BMP will check the availability with its own domain resources, and if it satisfies the request, it will parse the message to the downstream BMP and so on. Figure 6(a) shows the traffic pattern of source S0, which was in-profile.
Figure 7(b) shows the traffic pattern when the rate exceeds the profile (R0>C0), where the packet drops are more and the code point of the flow was degraded to different code point.
Figure 7 b: S1out-of-profile without BMP Figure 7(c) shows traffic pattern, for the source S1 with a rate under the profile (R1≤C1).
Figure 6 a: S1 out-of-profile with BMP Figure 6(b) shows the traffic pattern of source S1 generating at rate, which was out-of-profile. In this figure we can conclude that, BMP was able to allocate bandwidth by re-configuring the policy database, according to the availability of bandwidth end-to-end.
Figure 7 c: S0 out-of-profile without BMP Figure 7(d) shows the traffic pattern when the rate exceeds the profile (R1>C1). Figure 6 b: S0 in-profile with BMP Experiment 5: S0 & S1 out-of-profile without BMP management Experiment 5 was performed with S0 and S1 out-ofprofile. S0 generates traffic at a rate(R0)=3Mbps,CIR (C0)= 2Mbps, CBS=1KB. S1 generates traffic to destination rate (R1) =3Mbps,CIR (C1)= 2Mbps, CBS =1KB. Figure 7(a) shows traffic pattern, for the source S0 with a rate under the profile (R0≤C0), where the packet drops is at the minimal
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Figure 7 d: S0 out-of-profile without BMP Experiment 6: S0 & S1 out-of-profile with BMP Management Experiment 6 was performed in the lines of experiment 5 but with the involvement of BMP. This shows that the
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BMP can manage the bandwidth allocation from end-to-end with proper signaling among peer-BMP. Figure 8(a) shows the traffic pattern of source S0, which was in-profile, where BMP has nothing to be done.
“A Framework for Use of RSVP with DiffServ Networks.” IETF RFC 2998. [4] Nichols, K.; S.Blake; F.Baker; D.Black. 1998. “Definition of the Differentiated Services Field (DS field) in the IPv4 and IPv6 Headers.” IETF RFC 2474. [5] Nichols,K; V.Jacobson; L.Zhang. 1997.” A Two-Bit Differentiated Services Architecture for the Internet.” Internet-Draft,work in progress. [6] Schelen,O. 1998. “Quality of Service Agents in the Internet.” Phd. Dissertation, Lulea Tekinska University.
Figure 8 a: S1 out-of-profile with BMP
[7] Terzis, A; L.Wang; J.Ogawa; L.zhang. 1999. “A Two-Tier Resource Management Model for the Internet.” In IEEE Global Internet' 99
Figure 8(b) shows the traffic pattern of source S1 generating at rate, which was out-of-profile.
[8] QBONE The internet2 QBone Bandwidth Broker,2000 [9] Teitelbaum,B. at el. 1999. “Internet2 QBone:Building a Test bed for Differentiated Services.” IEEE Network. [10] Terzis,A; L.Wang; J Ogawa; L Zhang. 1999. “A Two-Tier Resource Management Model for Internet”. Global Internet 99. Figure 8 b: S0 out-of-profile with BMP
[11] Chan,K; J Seligson; D.Durham; S.Gai; K.McCloghrie; S.Herzog; F.Reichmeyer; R.Yavatkar; A.Smith. 2001. "COPS Usage for Policy Provisioning (COPS-PR)." IETF RFC 3084.
5 CONCLUSION In summary, we demonstrated a proof of concept how BMP will accomplish dynamic provisioning at interconnection peering in various network scenarios. We found the benefits of using BMP to improve network efficiency and QoS bandwidth utilization resulting in cost savings per interconnection for network service providers through various experiments using our BMP extension simulator. Our future work will focus on improving the capabilities of the agents. Some important QoS issues which we would like to address are end-to-end delay, loss, jitter performance.
[12] Foster ,I et al. 1999. “A Distributed Resource Management Architecture that Supports Advance Reservations and Coallocations.” In the Proceedings of IFIP/IEEE Intl Workshop on Quality of Service. (London,England). [13] Hwang, J. 2000. “A Market-based Model for Bandwidth Managemenet of Intserv-Diffserv QoS Interconnection.” Phd dissertation , University of Pittsburgh. [14] Mantar, H; J.Hwang; T. Iokumus; S.J.Chapin. 2001. “Inter-Domain Resource Reservation via Third-Party Agent.” SCI.
REFERENCES [1] Blake,S; D.Black; M.Carlson; E.Davies; Z.Wang; W.Weiss. 1998. “An Architecture for Differentiated Services.” IETF RFC 2475.
[15] Okumus,T; J.Hwang; H. A. Mantar; S.J Chapin. 2001 "Inter-Domain LSP Setup Using Bandwidth Management Points. ” submitted to Globecom 2001
[2] White,P.P. 1997. "RSVP and Integrated Services in the Internet: A Tutorial." IEEE Communications Magazine, pp.100-106.
[16] Qbone Signaling Design Team “Simple Inter-domain Bandwidth Broker Signaling (SIBBS).”, http://qbone.internet2.edu/bb work in progress.
[3] Bernet,Y; R. Yavatkar; P. Ford; F. Baker; L. Zhang; M. Speer; R. Braden; B. Davie; J. Wroclawski; E. Felstein. 2000.
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[17] Durham,D; J.Boyle; R.Cohen; S.Heroz; R.Rajan; A. Sastry. 2000. "Common Open Policy Service protocol (COPS)." IETF RFC 2478 [18] Breslau,L. et al. 2000 “Advances in Network Simulations”, In the proceeding of IEEE Computer. [19] Murphy,S. “Diffserv Package for ns-2.” http://www.teltec.dcu.ie/ns-work/diffserv/index.html [20] Braden,B. et al. 1997. "Recommendations on Queue Management and Congestion Avoidance in the Internet." IETF RFC 2309.
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