Tuesday, December 10, 2013

CoNEXT 2013 Student Workshop: Datacenter — Virtual Network Session

Traffic pattern based Virtual Network Embedding 
Authors: Andreas Blenk (Institute for Communication Networks, Technische Universität München, Germany), Wolfgang Kellerer (Institute for Communication Networks, Technische Universität München, Germany)
Presenter: Andreas Blenk

The paper focuses mainly on Virtual Network Embedding algorithms for Virtual Networks whose demand is changing according to the traffic patterns in order to provide high performance and resource efficiency.

Existing works try to optimise the embedding for load and reconfigurations while assuming that the demands of the virtual networks are fixed.  We propose a VNE algorithm based on Mixed Integer Linear Programming that looks ahead and finds a balance between an instantaneously optimal embedding and cost caused by future reconfigurations. The algorithm assumes that the changes of future virtual network demands are predictable as they may reoccur on a regular basis.

They conducted simulations with randomly varying number of nodes for the Poland IP network. They compare the results for three VNE scenarios namely, (1) pure load balancing, (2) consider load balancing and reconfigurations, and (3) consider load balancing, reconfigurations and traffic patterns.  Their results show that considering trafficc patterns decreases migrations while it does not diminish the link utilisation. Consequently, VNE algorithms should consider the trade of between migrations and utilization according to the impact of reconfigurations.

Q: What is the scalability of the network of MILP?
A: It's not very high, need some heuristics for larger networks

Q: What rate of changes that can be accommodated by the proposed mechanism?
A: depends on size of virtual networks, 

Q: Is exploiting diurnal trend for prediction a viable solution?
A: It's part of future work, can use machine learning

Virtualizing National Broadband Access Infrastructure 
Authors: Hassan Habibi Gharakheili (University of New South Wales), Vijay Sivaraman (University of New South Wales)
Presenter: Vijay Sivaraman

The authors of the paper focus on National Broadband Network of Australia which aims to provide 100 Mbps to over 93% of households in the country and considered the issue of virtualising and sharing the physical public network. The public network differs from a private network in the following ways: (1)It provides only wholesale  connectivity (layer-2 circuits) and Retail Service Provider (RSP) offers layer 3 services to the end users, and (2) allows the end user to have multiple RSPs per household. So the challenge here is finding the right set of interfaces in between the three entities namely Infrastructure operator, end users and RSPs to facilitate virtualisation and sharing .

The Benefits of virtualisation are as follows:

  • Better performance
  • dynamic capacity planing
  • pay-as-you go dynamic provisioning

  • several RSPs per household
  • several services at lower unbundled cost
  • customise the quality

Infrastructure Operatior: 
  • More efficient usage of network resources

The authors perform a simulation study based on the data they collected from UNSW wifi network with 30 Access Points and 8500 user sessions in total. In this study they evaluated fraction of unhappy user sessions and cost saving per RSP. Their preliminary results show that virtualisation reduces the RSP cost by 70% while allowing to have 90% happy sessions. The results also indicate that it needs time scale and bandwidth granularity tuning.

Q: As a user, is it a layer-2 or layer-3 virtualisation?
A: Layer 2 ,Each user will get a VLAN and they will run their web related services on top of it.

Q: Does NBN support mobility?
A: At the current stage it doesn't offer any mobility. 

Q: RSP will save money, what is the incentive for NBN?
A: It's difficult to say unless we have a pricing model in place

Q: What happens if there is a competition in between RSPs?
A: It based on pricing model

Q: How do you see users paying for different RSPs?
A: Currently it's payable for a single RSP, but for multiple RSPs it may be, line rental (base price) + usage (quota).
Or else we can have a broker in the middle, who can aggregate the RSPs, do the slicing and billing

Q: Would the service provider takes up this model, if so far the model is only used in Australia?
A: It would be good to experiment in one country to see how it works if content providers directly deals with the customer and then deploy in other countries as well.

Q: Any difference between SDN and broadband networks?
A: Completely different, when SDN is used in data centre under your control, but in Broadband Networks, there are three entities (RSP, users and government) and we have to come up with the right set of interfaces.

Towards Impactful Routing Research: Running Your Own (Emulated) AS on the (Real) Internet 
Authors: Brandon Schlinker (University of Southern California), Kyriakos Zarifis (University of Southern California), Italo Cunha (Universidade Federal de Minas Gerais), Nick Feamster (Georgia Institute of Technology), Ethan Katz-Bassett (University of Southern California), Minlan Yu (University of Southern California)
Presenter: Brandon Schlinker

The authors propose a testbed for use by operators and re- searchers wishing to examine the characteristics of inter- domain routing schemes.
The testbed also allows the emulated networks to advertise routes and exchange traffic with the real Internet. The testbed enables experiments to have complete control over the network topology. In addition, experiments can exchange routes and traffic with ISPs in multiple peering locations across the Internet, enabling experiments which emulate complex, geographically distributed networks.

The testbed provides operators and researchers with the ability to easily emulate complex autonomous system topologies while facilitating the exchange of routes and traffic with peers in Internet eXchange Points (IXPs) around the world. Thus, the testbed enables even a large ISP to emulate all aspects of their network infrastructure, including the complexities of their peering policies.

Q: Have you considered any adversarial model?
A: Consider route flapping, doesn't impact the proposed mechanism. Consider prefix hijacking,  which BGP is designed to withstand.

Q: Can you measure paths to the emulated network?
A: It's possible to perform. 

Q:  You considered multiple private AS in one Mininet, can you put it in different machines?
A: Yes, by advertising prefixes into BGP multiplexers

Q: If you want to work with BGP, you don't have much freedom to change, what do you think about it?
A: True, We have to deal with how to have different scenarios

Q: What sort of usage model can be used?
A: provide more resources to gain more

Parallel Routing on Multi-Core Routers for Big Data Transfer 
Authors: Ahmet Soran (University of Nevada Reno), Furkan Mustafa Akdemir (Bilkent University), Murat Yuksel (University of Nevada Reno)
Presenter: Ahmet Soran

The authors considered big-data is being transferred and address the issue of using multi-core routers effectively and efficient to route such transfers. The authors propose a parallel routing architecture that explicitly considers multi-core routers and employs shortest-path calculations. The basic idea is to virtually slice the router topology into and assign them to a separate router core, which calculates a shortest path on the assigned slice.

The design goal of parallel routing is to generate virtual slices that yield the most diverse and non-overlapping shortest paths possible. The authors try Graph based and Flow based approaches in their simulation study and and evaluated the heuristics on the Sprintlink topology of the Rocketfuel dataset. They test their heuristics against the ground truth, namely single shortest path case. Their preliminary results show that  parallel routing heuristics achieve higher throughput against the single core routing. 

Q: What sort of challenges on parallelising path routers?
A: transforming parallelisation into 2 different problems, 1) slicing and 2) load balancing

Q: Will the data from the same flow be split?
A: Yes

Q: Have you talked to Network Operators to get an idea of multi-core routers?
A: Yes, we are planing to run experiments in their network.

Q: You used Rocketfuel Topology which is not accurate, what is your comment?

A: Parallel routing perform better

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