The Future of TCP: Train-wreck or Evolution?

Abstract:
In this demo we will focus on the inter-play of TCP congestion control mechanisms and opportunistic wireless schedulers such as Proportional Fair Sharing (PFS). Specifically, we consider a cellular setting that is capable of packet scheduling both in the forward and reverse links. Our demo will stress on the facts that (i) TCP suffers substantially when there is a high degree of rate/load asymmetry in the forward and reverse directions, (ii) TCP is vulnerable when a mobile host has payload traffic in both directions, and (iii) the fairness notion adopted at the wireless schedulers are not necessarily compatible with the per flow fairness of TCP. Since majority of video streaming applications in the current Internet use TCP, our demo will compare video streaming sessions over TCP vs. a backlogged system under the same network and wireless channel conditions.

Slides [.ppt]

Abstract:
TCP has not been designed to cope with the complex interference found in static multi-hop wireless (mesh) networks. This interference makes congestion and rate control a neighborhood, not a single-node affair, and unless TCP explicitly accounts for this, its performance can be spectacularly bad. We use simulation and experimental results to showcase this fact and explain the origins of the problem, which points to some ways of fixing it. Conceptually, such fixes are evolutionary (in the sense that one should be able to retrofit them into TCP), but one would have to change the TCP implementation a fair bit to accommodate this.

Slides [.pdf]
Demo Video I [.mov]
Demo Video II [.mov]
Demo Video III [.mov]

Abstract:
This demo highlights the limitation of TCP for supporting video streaming over wireless, in the presence of heterogeneous link speeds. The setup mimics a wireless home network with several nodes operating in 802.11 ad-hoc mode. We demonstrate the impact of a file transfer session over a slow link on an ongoing video streaming session over a fast link. TCP leads to approximately equal throughput for both sessions, despite difference in their link speed, causing severe quality degradation of the video stream.

Slides [.ppt]
Demo Video I [.asf]
Demo Video II [.asf]

Abstract:
The number and size of datacenters are growing exponentially, driven by businesses such as Google, Amazon, and the Wall Street trading firms. Essentially all the network applications in these datacenters depend on TCP. Yet in datacenters, the bandwidth, latency, cost, and congestion parameters that affect TCP are drastically different than in the wide-area Internet. We explore a few issues with TCP and demonstrate that its implementation today is far from optimal for the datacenter.

Slides [.ppt]

Abstract:
Multimedia home networks are becoming big business, with over 30 million households expected to have multimedia networks by 2010, and home entertainment projected to reach $12B by 2009. Users can use home entertainment applications, many of which currently run on TCP, to stream audio and video to many rooms, share photos, songs and movies, and support security cameras and data applications. In this talk, we will demonstrate that TCP's architecture, which was designed for elastic applications on wired networks, is fundamentally not suited either to the challenges posed by lossy wireless networks and streaming multicast applications, or to the opportunities presented by wireless mesh networks.

Slides [.pptx]
Demo Video I [.mpeg]
Demo Video II [.mpeg]
Demo Video III [.mpeg]
Demo Video IV [.mpeg]

Abstract:
Today, the capacity and the usage of the Internet is fundamentally changing. In the forthcoming year, millions of homes will have access to the Internet with Fiber lines. Network companies will offer speeds on Fiber of up to 1Gbps. Consequently, ultra-high-speed applications will be enabled at low-cost, such as high-definition teleconferencing, telemedicine and advanced telecommuting for people working from home. We then propose a demonstration which aims at showing that the traditional congestion control approach may present a strong barrier to the large scale deployment of these exciting and very useful envisioned applications exploiting the emerging huge access capacities.

Slides [.pdf]

Abstract:
Cloud services such as those provided by Amazon, Microsoft, Google are proliferating. On one hand they offer the convenience of services such as computing and storage on demand, and accessible content anytime anywhere; on the other hand, access to these services can be painfully long through WAN links which often have long round-trip times, are lossy, and shared across a lot of simultaneous users. In this demo, we take a particular example of uploading user-generated content such as HD video clips to the cloud. We are interested in the metric -- how quickly is the content shareable? The demo illustrates the painfully long "Time to Share" in part due to TCP congestion control, and contrasts it with the quick sharing time of an "ideal" solution.

Slides [.pdf] [.mov]