What's on IPTV's neighbourhood?

Wednesday, 25 March 2009

OFC 2009, Day 2

OFC is a very big conference, with several interesting things happening at the same time. Therefore, we have to be very judicious in the choices we make. Some of the talks are quite good, but many of them are really uninteresting, or the speakers are really poor, or are just very nervous. So I will only make notes of talks I think were worthy somehow... which will leave probably half out.

In this first day of technical presentations I seem to have perceived a trend: the optical community is trying to tie itself closer together with the internet community. There was a talk by someone from the National Science Foundation and also another from the GENI project where this was quite clear. But let me leave in here some details on a number of talks.

"Global Load Balancing of Zero-Bandwidth TE LSPs in MPLS Networks"

The first author of this paper is Filippo Cugini (from CNIT), but the presenter was Francesco Paolucci, from Scuola Superiore Sant’AnnaItaly. Cugini is one of the co-authors of the paper I will present tomorrow. It is interesting to note that Francesco's group is probably the "winner" of this year's OFC. They have 11 papers here, which is certainly the highest number for a single institution. Our paper is part of the list, since besides Cugini, Alessio Giorgetti and Prof. Castoldi are also co-authors.

They proposed an iterative algorithm to achieve global load balancing of zero-bandwidth TE LSPs (keeping it simple, these are low priority LSPs). They have realised that commercial MPLS routers present very poor balancing for this type of traffic. The algorithm is neat, and it seems to work, but I had some doubts about its scalability. I think they didn't dive into to this problem in-depth. I will probably chat with them over dinner one of these days and try to clarify this... :)

"Availability-Guaranteed Connection Provisioning with Delay Tolerance in Optical WDM Mesh Networks"

The first author and presenter was Cicek Cavdar, from Istanbul Technical Univ. (ITU), Turkey. They have exploited delay tolerance to decrease blocking in availability guaranteed shared-path-protected optical WDM networks. They reduce blocking probability without sacrificing additional resources. This is the first proposal using the time dimension to help mitigate this problem.

"LSP Request Bundling in a PCE-Based WDM Network"

The first author of this paper is Jawwad Ahmed, Royal Inst. of TechnologySweden, but I am not sure if he was the one presenting it (I didn't pay attention in the beginning of the session). They propose the bundling of LSP requests to improve network optimization, at the expense of an increased connection setup delay. Basically these requests are sent to a centralised element (the PCE) and it may make sense to bundle these requests, to reduce the overhead in the network. Their approach showed that for a connection holding time of 20 seconds or less it makes sense doing this. But 20 seconds is a very low figure, I think, for a core network. I was not totally convinced with their results, and I think this topic is worth exploring a bit more.

"IP and Optical Integration in Dynamic Networks"

This was an invited talk by Ori A. Gerstel, from Cisco Systems (I attended a short course by the speaker on Sunday, but the talk was more interesting). The main question addressed was: "how to have a fully dynamic optical network?". He discussed the real-world needs for such dynamism, and how to enable IP/optical capabilities that will make this technology deployable. Some notes:

1. He thinks this will be a stepwise evolution (not a revolution). Some of the steps he mentioned and that interest me more are a) the creation of an automated control plane inside the optical network, b) the possibility of triggered lightpaths setup from the router, and c) optical packet switching. About this last point he is very sceptical. Me too, at least for the short-medium term: where are optical buffers and packet header processing at the optical level?

2. Some papers worth reading: "Handling IP traffic surges...", by Pongpaibool et al., and "Towards deployment of signalling based approaches...", by Salvatory e al. (ECOC 2008).

"Optical Communication Challenges for a Future Internet Design"

Another invited talk, this time a more "political" one. The speaker was Darleen Fisher, from the Natl. Science Foundation (NSF), USA. She talked about the challenges faced by the optical research community. She mainly talked about FIND (Future Internet Design), and their clean slate approach for network research. It was interesting to note that the NSF is attempting to join the optical networking people with the Internet people. One example is the DOCS project, where they are mixing people from the optical area with internet researchers (like Nick McKeown). 

The questions in the end were quite interesting, with two optical researchers asking the speaker why optical research doesn't get more money, and specifically why it gets way less money than wireless projects... :)

"Survivable Logical Topology Design for Distributed Computing in WDM Networks"

Xiang Yu, from SUNY Buffalo, USA, presented an MIP formulation and an efficient heuristic for the problem of logical topology design for a distributed computing application to survive one computing cluster failure and one fibre link failure in WDM networks. This is a NP-hard problem, so he presented a MIP formulation (not scalable) and then also a heuristic. Unfortunately, he didn't manage his time well, so he skipped the most important part - the results. The little time he used for this was to say the obvious, so in the end it was not at all useful. This was the example of a talk that, for not being well prepared, wasn't able to pass a message that could be of interest to some of the audience.

"Experimental Demonstration of SIP and P2P Hybrid Architectures for Consumer Grids on OBS Testbed"

Lei Liu from the Key Lab of Optical Communication and Lightwave Technologies(OCLT), Ministry of Education, Beijing Univ. of Posts and Telecommunications, presented a paper where he proposed three types of SIP and P2P hybrid architectures for consumer grids. The idea of a hybrid architecture was interesting, turning the centralised client/server model of SIP into a P2P one. Unfortunately, again, he spent all his time explaining the architectures, and skipped the results section...

"GENI: Overview and Plans"

This was an invited presentation where, again, one could see the attempt to join the optical community with the computer nets community. GENI, the Global Environment for Network Innovations, is a suite of experimental network research infrastructure being planned and prototyped in work sponsored by the NSF, and was presented by Kristin
Rauschenbach, from BBN Technologies. The idea is that researches can use a "slice" of the infrastructure for long running, realistic experiments, so simultaneous experiments, radically different, will be running in parallel. They aim to glue together heterogeneous infrastructure (avoiding technology "lock in").

On the optics side, the GENI goal is to enable computer people direct access to optics (by virtualisation of optical capabilities and programmable optics). Someone asked what the cost for a singular researcher using GENI is, and the speaker answered that the cost would probably be part of the NSF funding contracts. So if a researcher wants to use a "slice" as part of his or her work, they do not seem to have a "cost table" for that. At least not now.

"Light-Mesh: An Evolutionary Approach to Optical Packet Transport in Access Networks"

Ashwin Gumaste, from the Indian Inst. of Technology at BombayIndia, has presented a paper proposing an alternative solution to PONs. PONs require lots of optical fibres (hence, high costs), and so their system is a "light mesh" concept, with the objective of reducing the number of fibre links needed. They have built a test bed, and they were able to achieve optical packet transport using mature off-the-shelf components. Though their system is prone to collisions, with the algorithms they use (CSMA-CD-like), they seem to achieve low delays.

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