Yijun Xiong

Control architecture in optical burst-switched WDM networks

Optical burst switching (OBS) is a promising solution for building terabit optical routers and realizing IP over WDM. In this paper, we describe the basic concept of OBS and present a general architecture of optical core routers and electronic edge routers in the OBS network. The key design issues related to the OBS are also discussed, namely, burst assembly (burstification), channel scheduling, burst offset-time management, and some dimensioning rules. A nonperiodic time-interval burst assembly mechanism is described. A class of data channel scheduling algorithms with void filling is proposed for optical routers using a fiber delay line buffer. The LAUC-VF (latest available unused channel with void filling) channel scheduling algorithm is studied in detail. Initial results on the burst traffic characteristics and on the performance of optical routers in the OBS network with self-similar traffic as inputs are reported in the paper.

Design and analysis of optical burst-switched networks

Optical burst switching (OBS) is a promising solution for building terabit optical routers and realizing IP over D- WDM. In this paper, we describe the basic concept of OBS and a general architecture of optical routers. The key design issues related to the OBS are discussed, notably, burstification, offset-time management and channel scheduling. A simple channel scheduling algorithm called LAUC (Latest Available Unscheduled Channel) algorithm is presented, which is also called Horizon algorithm in the literature. The performance of optical routers under random and self-similar traffic is thoroughly studied via computer simulations. Our study indicates that the distribution of burst length is not exponential any more. For the FDL (fiber delay line) optical buffer, the burst loss ratio is quite sensitive to the traffic characteristic of bursts when using the LAUC algorithm.

Evaluation of multicast schemes in optical burst-switched networks: the case with dynamic sessions

In this paper, we evaluate the performance of several multicast schemes in optical burst-switched WDM networks taking into accounts the overheads due to control packets and guard bands (Gbs) of bursts on separate channels (wavelengths). A straightforward scheme is called Separate Multicasting (S-MCAST) where each source node constructs separate bursts for its multicast (per each multicast session) and unicast traffic. To reduce the overhead due to Gbs (and control packets), one may piggyback the multicast traffic in bursts containing unicast traffic using a scheme called Multiple Unicasting (M-UCAST). The third scheme is called Tree-Shared Multicasting (TS-MCAST) wehreby multicast traffic belonging to multiple multicast sesions can be mixed together in a burst, which is delivered via a shared multicast tree. In [1], we have evaluated several multicast schemes with static sessions at the flow level. In this paper, we perform a simple analysis for the multicast schemes and evaluate the performance of three multicast schemes, focusing on the case with dynamic sessions in terms of the link utilization, bandwidth consumption, blocking (loss) probability, goodput and the processing loads.