1. Yu-Liang Liu1 On the Bandwidth Management for Hose-Model VPN Service GRADUATE INSTITUTE OF INFORMATION MANAGEMENT NATIONAL TAIWAN UNIVERSITY

2. Yu-Liang Liu2 Outline An Introduction to VPN VPN Service Models (Bandwidth management) –T–T–T–The pipe model –T–T–T–The hose model Implementation Alternatives of the Hose Model VPN Hose-Model VPN Service Provisioning Future Works

3. 3 Private Network A Private Network (PN) is established by dedicated leased lines connecting several geographically dispersed sites (endpoints).A Private Network (PN) is established by dedicated leased lines connecting several geographically dispersed sites (endpoints). –Each site is a campus or a branch office of an enterprise. –Since the lines are dedicated, security and Quality of Service (QoS) are ensured. –But connecting a large number PN sites with dedicated lines is expensive.

4. Yu-Liang Liu4 Virtual Private Network Virtual Private Network (VPN) is a replacement for Private Network.Virtual Private Network (VPN) is a replacement for Private Network. –A VPN establishes connectivity between a set of endpoints over a shared network infrastructure (eg: MPLS network backbone). –The goal of VPN is to provide endpoints with a service comparable to Private Network. –Thus providers of VPN services need to address QoS and security issues.

5. Yu-Liang Liu5 VPN Three Types In terms of commercial applications, VPN can be classified into three types:In terms of commercial applications, VPN can be classified into three types: –Access VPN (a.k.a Remote Access VPN) –Intranet VPN (a.k.a Enterprise VPN) –Extranet VPN (a.k.a E-commerce VPN)

6. Yu-Liang Liu6 VPN Three Types (con ’ t) Enterprise A Enterprise B Enterprise A Nomadic user Shard Network or

7. Yu-Liang Liu7 Outline An Introduction to VPN VPN Service Models (Bandwidth management) –T–T–T–The pipe model –T–T–T–The hose model Implementation Alternatives of the Hose Model VPN Hose-Model VPN Service Provisioning Future Works

8. 8 VPN Service Models VPN customers need a flexible ways to specify their bandwidth requirement.VPN customers need a flexible ways to specify their bandwidth requirement. Two common VPN service Models areTwo common VPN service Models are –The Customer-pipe model –The Hose model

9. Yu-Liang Liu9 The Customer-Pipe Model In this model, VPN customers buy a customer-pipe for each endpoints pair.In this model, VPN customers buy a customer-pipe for each endpoints pair. VPN customers need to specify bandwidth requirement of each customer-pipe in advance.VPN customers need to specify bandwidth requirement of each customer-pipe in advance. VPN service provider uses a path between endpoints pair to implement a customer- pipe.VPN service provider uses a path between endpoints pair to implement a customer- pipe. –VPN service provider also need to allocate adequate bandwidth along the path.

10. Yu-Liang Liu10 The Customer-Pipe Model (con ’ t)

11. Yu-Liang Liu11 The Pro and Cons of the Customer Pipe Model ProPro – The task of bandwidth allocation becomes more simple. ConCon –It requires the customer to have precise knowledge of the bandwidth requirement of each endpoints pair in advance. –Bandwidth made available to a customer pipe cannot be allocated to other traffic.

12. Yu-Liang Liu12 Motivation for the Hose-Model VPN customers may unwilling to unable to know the bandwidth requirement between each endpoints pair in advance.VPN customers may unwilling to unable to know the bandwidth requirement between each endpoints pair in advance. –This is especially true when the number of endpoints per VPN is large.

13. Yu-Liang Liu13 The Hose Model In this model, VPN customers only need to specify two parameters for each endpoint:In this model, VPN customers only need to specify two parameters for each endpoint: Egress bandwidth requirement: the bandwidth for aggregate outgoing traffic from the endpoint to all the other endpoints.Egress bandwidth requirement: the bandwidth for aggregate outgoing traffic from the endpoint to all the other endpoints. Ingress bandwidth requirement: the bandwidth for aggregate incoming traffic out of all the other endpoints to this endpoint.Ingress bandwidth requirement: the bandwidth for aggregate incoming traffic out of all the other endpoints to this endpoint.

14. Yu-Liang Liu14 Advantages of the Hose Model Ease of specificationEase of specification FlexibilityFlexibility

15. Yu-Liang Liu15 Challenge of Provision the Hose Model VPN From a VPN service provider ’ s perspective, it is more challenging to support the hose model VPN:From a VPN service provider ’ s perspective, it is more challenging to support the hose model VPN: –The need to meet the bandwidth requirement with a very weak specification. –This complicate the VPN ’ s bandwidth management issue.

16. Yu-Liang Liu16 Outline An Introduction to VPN VPN Service Models –T–T–T–The pipe model –T–T–T–The hose model Implementation Alternatives of the Hose Model Hose-Model VPN Service Provisioning Future Works

17. Yu-Liang Liu17 Implementation Alternatives of the Hose Model The most important implementation alternatives for the hose model VPNs are:The most important implementation alternatives for the hose model VPNs are: –Provider-pipe algorithm –Hose-specific state algorithm –VPN-specific state algorithm –Tree routing algorithm

18. Yu-Liang Liu18 Provider-Pipe scheme

19. Yu-Liang Liu19 Hose-specific state scheme

20. Yu-Liang Liu20 VPN-specific state scheme

21. Yu-Liang Liu21 Tree Routing Scheme

22. Yu-Liang Liu22 Is the Hose Model a Viable Alternative The main question to introduce the hose model in ISP networks is how does it relate to the customer pipe solution in terms of bandwidth efficiency.The main question to introduce the hose model in ISP networks is how does it relate to the customer pipe solution in terms of bandwidth efficiency. The flexibility of the hose model will never pay off if it requires significant overprovisioing compared to customer-pipe models.The flexibility of the hose model will never pay off if it requires significant overprovisioing compared to customer-pipe models.

23. Yu-Liang Liu23 Generate Comparable Hose Model Parameters Endpoint 1 Endpoint 2 Endpoint 3 Endpoint 1 12 Endpoint 2 11 Endpoint 3 31 Ingress Bandwidth Egress Bandwidth Endpoint 1 43 Endpoint 2 22 Endpoint 3 34 Customer-Pipe Model parameters : Hose-Model parameters :

24. Yu-Liang Liu24 Overprovisioning Factor The ratio between the bandwidth reservation of the hose and the customer-pipe model is called overporvisioning factor. It is a good indicator of the required extra capacity.The ratio between the bandwidth reservation of the hose and the customer-pipe model is called overporvisioning factor. It is a good indicator of the required extra capacity.

25. Yu-Liang Liu25 Experimental Results Provider-pipe Hose-specific state Tree routing VPN-specific state

26. Yu-Liang Liu26 Experimental Results

27. Yu-Liang Liu27 Outline An Introduction to VPN VPN Service Models (Bandwidth management) –T–T–T–The pipe model –T–T–T–The hose model Implementation Alternatives of the Hose Model VPN Hose-Model VPN Service Provisioning Future Works

28. Yu-Liang Liu28 Hose-Model VPN Service Provisioning In terms of VPN service provisioning, service provider must establish multiple VPNs on the network backbone in an on-line manner.In terms of VPN service provisioning, service provider must establish multiple VPNs on the network backbone in an on-line manner. –The available bandwidth for VPN service on links of the network backbone is finite. –VPN setup request arrive one by one independently. –Each VPN setup request corresponds to a Hose- Model VPN to be established. –Information about future VPN setup request is unknown.

29. Yu-Liang Liu29 Hose-Model VPN Service Provisioning If there is not enough residual bandwidth on the link when the bandwidth is being allocated, vr i will be rejected.If there is not enough residual bandwidth on the link when the bandwidth is being allocated, vr i will be rejected. In this scenario, the performance metric for comparing different VPN provisioning algorithm is rejection ratio.In this scenario, the performance metric for comparing different VPN provisioning algorithm is rejection ratio.

30. Yu-Liang Liu30 Example In this scenario, even tree routing algorithm cannot achieve rejection ratio.In this scenario, even tree routing algorithm cannot achieve rejection ratio. –Service provider received two VPN setup requests vr 1 =(2,3,3) and vr 2 =(3,3,3). –The available bandwidth on all links is 5 units.

31. Yu-Liang Liu31 Rejection Ratio of Tree Routing Scheme vr 2 will be rejected, the rejection ratio achieved is 50%.

32. Yu-Liang Liu32 Optimal Arrangement Both VPN setup requests will be accepted, the rejection ratio achieved is 0%.

33. Yu-Liang Liu33 Modified Tree Routing Algorithm The design philosophy of MTRA is to look after both bandwidth allocation efficiency and load balance.The design philosophy of MTRA is to look after both bandwidth allocation efficiency and load balance. –It can reduce rejection ratio effectively.

34. Yu-Liang Liu34 Parameters Configuration

35. Yu-Liang Liu35 Experimental Results

36. Yu-Liang Liu36 Future Works In order to ensure service quality and availability of VPN services, seamless recovery from failures is essential. In order to ensure service quality and availability of VPN services, seamless recovery from failures is essential. −Failure restoration algorithm for Hose-Model VPN.

37. Yu-Liang Liu37 Recovery from Link Failure 123 4 Tree Link (1,4) fail and the corresponding backup path is activated: