Project Suggestions

The following is a list of possible projects for CPSC 633a. These are simply recommendations. You are encouraged to come up with your own ideas for topics. Some suggested projects will need kernel access, and I will provide the machine. Some other projects maybe best carried out using simulations. A nice network simulation package is ns-2. The package is written in C++ and Tcl. You can read the online tutorial. You can also listen to the workshop online.

• TBIT
  We have covered several versions of TCP congestion control: TCP/Tahoe, TCP/Reno, TCP/Vegas. Each version has various requirements and options that should be provided as specified in various RFCs. TCP is designed such that the TCP receiver is the same under these various versions, and that the differences are implemented at the sender side of the protocol. What is the fraction of servers that are implementing a particular version of TCP? Are they implementing all of the options correctly? TBIT is a tool developed at ACIRI (AT\&T Center for Internet Research at ICSI in Berkeley, CA) that connects with a server using a TCP connection and probes the server by varying the behavior at the receiver end in such a way that it is possible to distinguish between versions, and can test whether certain options / requirements are being met. Researchers at ACIRI have posed several questions that their TBIT tool cannot yet detect, but that they are interested in adding to the tool. 
  Starting point:  http://www.aciri.org/tbit. Groups embarking on this project would likely get the opportunity to interact with the folks at ACIRI, which is in itself a fantastic opportunity.

• Security attacks on end-to-end congestion control
  The stability of the Internet depends on end-to-end congestion control. An end-to-end congestion control scheme assumes the cooperation of  many entities: senders, receivers, and network elements such as routers. When some of these entities turn malicious, they can cause harm to the network. What are the attacks? How do you identify and prevent the attacks?  
  Starting point: papers in the class.

• Application-specific evaluation of new TCP-friendly congestion control algorithms
  In this class, we will read [BBFS01], which evaluates the effects of new TCP-friendly congestion control algorithms. However, the evaluation is independent of any application. It will be more informative if you evaluate the algorithms in the context of a specific class of applications such as streaming media. Also, in order to carry out this project, you will need to use Congestion Manager, which is a modification of the Linux kernel. Therefore, the experience can be pretty rewarding.
  Starting point: papers in the class. Congestion manager.

• Improve secure group key management by considering user behaviors
  In this class, we will evaluate the key tree algorithm for implementing group key management. However, the design and the evaluation of the algorithm did not consider the effects of user behaviors. What if the users have different behaviors? For example, some users may join and leave more frequently than other users. Where do we place such active users on the key tree? If we can partition the users into several groups, how do we partition the users if we know their profile? Even further, what if a user may join several correlated groups, how do we structure the key tree for related groups? A single key tree for related groups? Several key trees?
  Starting point: papers in the class.

• Comparison and improvement of content based routing algorithms
  One recent trend in computer networks is peer-to-peer networks. Compared with the current Internet, one class of peer-to-peer networks can be considered as a distributed storage system with the capability to search by content. In other words, one of the most interesting perspective of peer-to-peer network is their content based routing algorithms. Researchers have already proposed several schemes. It will be interesting to compare them. Also, you may consider possibilities to improve the performance.
  Starting point: The papers in class reading list. Also, http://www.openp2p.com/ 

• Search by key words in content based routing algorithms
  All of the proposed content based search algorithms assume that the searching user knows the key of a data item. Usually, the key is generated by applying a hash function on the content of a data item. Therefore, if a user does not know about the item, the user cannot search for the item. An interesting question then is whether we can allow search by partial matching. To make the problem more interesting (you don't need to consider this constraint), most systems are designed to disallow key words searching due to legal and security concern. Can you strike a balance?
  Starting point: The papers in class. Also, http://www.openp2p.com/ 

• Will GPS clock help?
  One performance issue of TCP is that the clocks of a TCP sender and its receiver are not synchronized. Therefore, the sender can only measure round-trip time, which adds the noise from the feedback loop. By equipping end systems with cards that receive GPS synchronized clock signals, the sender and the receiver can accurately measure delays within 1-2 micro second. Can this improve performance? When? By how much? Is this a good idea?

• Retransmission strategy in wireless environments
  In wireless environment, packet losses are highly correlated; therefore it is possible that many packets in a window are dropped. In this scenario, can we improve performance by using the go-back-n scheme for retransmission? In other words, will it be beneficial if we retransmit all the outstanding packets after we detect a packet loss?

• Hot-spot in wireless mobile networks
  There are two types of wireless and mobile infrastructure: cell-based and ad hoc based. In the cell-based infrastructure, everything needs to go through the base station:  communications between devices in the same cell as well as communications between a device in the cell and the outside world. In an ad hoc network, devices communicate with each other without going through the base station. Some recent study shows that the majority of the traffic is between a device and the Internet. That is, even if we have ad hoc network, we still need to go through the base station to the other network. Can we gain performance if we have a hybrid architecture?
  Starting point: [CW01] Chunming Chao, Hongyi Wu, "iCAR: an Integrated Cellular and Ad-hoc Relay System". In Proceedings of International Conference on Computer Communications and Networks (IC3N), Las Vegas, NV, Oct. 2001.

• Reliable multicast transport protocols in wireless Ad Hoc networks
  Ad-hoc networks are collections of mobile nodes communicating using wireless media, without any fixed infrastructure. Conventional reliable multicast schemes are inadequate in these scenarios, as the mobility aspect can cause rapid and frequent changes in network topology. How do you implement reliable multicast in this environment? Are there tradeoffs in terms of power usage and wireless bandwidth consumption? To visualize the importance of this problem, you can think of the ad hoc nodes as the agents of US special workforce carrying on operations in Afghanistan.
  Starting point: http://www.isi.edu/imahn/

• RED inference
  Random Early Detection (a.k.a., RED) is a policy being implemented in Internet routers whereby packets are dropped probabilistically, where the probability that a packet is dropped is an increasing function of the exponentially weighted average of the size of the router's buffer in use. Is RED working in practice? Before this can be answered, one first needs to know to what extent is RED being deployed. However, it is often not easy to ascertain this information from ISPs. Can it be inferred from the end-hosts as to whether or not a router, or set of routers along a given network path, are using RED? Can you detect their configurations?
  Starting point: [FJ93]

• Bandwidth allocation for multi-party applications
  Multi-party applications, such as Internet video/audio broadcasts, or videoconferencing, have the potential to usurp large shares of network bandwidth. How should these protocols be designed so that they share bandwidth ``fairly'' with other applications using the Internet? This problem has two interesting parts: what is a ``fair'' share for such an application? Once it is determined what is meant by a fair share, how can this fair share be realized?

• Soft state tradeoffs
  Soft-state is a mechanism style used by communication protocols in which a client node maintains some default state that it reverts to if it is not contacted by its parent periodically. The mechanism increases the fault tolerance of the network because when network faults partition communication, the system reverts to a default state. However, soft-state has a cost in terms of the bandwidth required to simply keep the connection alive, as well as the automatic termination of connections during a partition. Is there a good model that can be used to examine these tradeoffs?
  Starting point: [RC99] Suchitra Raman and Steven McCanne, "A Model, Analysis, and Protocol Framework for Soft State-based Communication". In Proceedings of ACM SIGCOMM 1999.

• Network infrastructure for ubiquitous devices
  It is commonly stated that soon, every household device will have its own IP address and will become a component of the Internet. What sorts of changes need to be made to the current IP infrastructure to support the needs, as well as the numbering, of these devices?

• New name service
  DNS was designed under the assumption that hosts would remain fixed. However, it turns out that people are not interested in reaching a given host - they are more interested in reaching the information that might exist on the host. DNS is not designed to handle information that might reside on a set of hosts for a short period of time before being moved to other sites. How can DNS be modified to support these migration services, or should a new protocol be designed to replace current DNS?
  Starting point: The Active Names project.

• Aggregated multicast support in NS2