Optical burst switching (OBS) is thought to be the best way to adapt the bursty IP traffic over optical WDM networks.
It provides statistical multiplexing gains and avoids long end to end setup time of traditional virtual circuit configuration.
However, under the current and foreseeable limitations of optical technology, performance of OBS is mainly hampered
at network nodes by burst contention. The contention is serious constraints on the capacity of OBS networks. A leading
source of contention is the congestion at congested links where a limited number of wavelengths are shared by a lot of
bursts. These congested links are stemming from burst routing algorithms. In this paper, we studied on routing path
competition phenomenon. We proposed a differentiated QoS aware multipath routing algorithm for OBS networks. This
algorithm is evaluated through extensive numerical studies over a typical topology--the 14-node NSFnet. Results show
that it outperforms the existing algorithms in terms of burst blocking probability and link utilization.
Optical burst switching (OBS) is proposed as a high speed, flexible and transparent switching technology. It
facilitates the efficient integration of both IP and WDM. And it provides statistical multiplexing gains and avoids
long end to end setup time of traditional virtual circuit configuration. However, under the current and foreseeable
limitations of optical technology, performance of OBS networks is mainly hampered at the network nodes by
resource contention. Due to the fact that the random access memory is not available in the optical domain, there
exists a real possibility that bursts may contend with one another at a switching node. Therefore, many contention
resolutions are proposed, such as fiber delay lines, wavelength conversion, and deflection routing, etc. These
resolutions are focus on the node design. They are increase the complexity of the node. But they can not always
take some significant effect and make notable gains in cost-efficiency. In this paper, unlike these schemes are focus
on the node design, we proposed a novel link architecture named dual-fiber-link (DFL) for OBS networks. We also
proposed a relative media access control protocol. We have developed some scenarios to evaluate this architecture.
Simulation results show that the proposed link can decrease packet drop probability in terms of orders of
magnitude in OBS networks without optical buffers and wavelength conversions.
Under the current and foreseeable limitations of optical technology, performance of the next generation optical network is mainly hampered at the network node by resource contention. Existing work addresses contention resolution mostly in the wavelength domain (as wavelength conversion, WC), the time domain (buffering by using fiber delay lines, FDLs, the space domain (as deflection routing), and the burst domain (as segmentation). In this paper, a new architecture of optical networks-the server view based on optical networks is proposed. From the point of this new architecture, the network can be modeled as a server system with three type servers-the access server, the node server and the link server. The network performances such as cost, energy consume and network capacity can be affected by the capability of these three type servers. Unlike existing research activities that are focused on the node server design, we present the Dual fiber link (the link server solution) and IP calking (the access server solution) to ease the resource contention. To evaluate the performance of the proposed methods, computer simulations are conducted. The simulation results show these solutions can reduce the contention effectively with existing commercial devices.
Optical burst switching (OBS) is proposed as a high-speed, flexible, and transparent technology. It is thought
to be the best way to adapt the bursty IP traffic over optical wavelength division multiplexing (WDM) networks.
OBS technology facilitates the efficient integration of both IP and WDM. It provides statistical multiplexing
gains and avoids long end to end setup time of traditional virtual circuit configuration. However, there are still a
lot of challenges, one of which is burst contention. Owing to the fact that random access memory like buffering
is not available in the optical domain at present, there exists a real possibility that bursts may contend with one
another at a switching node. Many contention resolutions are proposed. The major contention resolutions in
literature are wavelength conversion, fiber delay lines, and deflecting routing. In this paper, a new data burst
scheduling scheme, called group scheduling based on control-packet batch processing (GSCBP) was proposed to
reduce burst contention. Like transmission control protocol, GSCBP has a batch processing window. Control
packets which located in the batch processing window are batch processed. A heuristic scheduling algorithm
arranges the relevant bursts' route based on the processing result and the network resource. A new node
architecture supporting group scheduling was presented. The GSCBP algorithm is combined with wavelength
converter and/or fiber delay lines which is shared by some data channels. Meanwhile, an extended open shortest
path first (E-OSPF) routing strategy was proposed for OBS. Both GSCBP and E-OSPF are introduced into
14-node national science foundation network by means of simulations. The ETE delay, burst blocking probability,
as well as burst dropping probability were attained. Results show that the GSBCP lead to the higher-priority
traffic drop rate decrease one order of magnitude, if drop rate and ETE delay of lower priority traffic is sacrificed.
Optical burst switching (OBS) is thought to be the best way to adapt the bursty IP traffic over optical
wavelength division multiplexing (WDM) networks. OBS technology facilitates the efficient integration of both
IP and WDM, and it provides statistical multiplexing gains and avoids long end to end setup time of traditional
virtual circuit configuration. However, burst contention is inescapable in OBS for connectionless transmission
and the absence of optical random-access memory. So many contention resolution methods are proposed. In this
paper, a novel decrease contention scheme--IP calking was proposed for optical burst switched networks. IP
calking method uses IP packets to carry single-hop traffic and the burst to carry multihop traffic as well, filling
gaps between bursts by stuffing IP packets between adjacent nodes. A statistical analysis model was developed
to analyze the performance of this method. In an arbitrary network, the analyses indicate that the decrease of
packet dropping probability is directly proportional to the link number and almost inversely proportional to the
square of the node number. The theoretical results are validated through extensive simulations. Simulation
results show that IP calking decreases about 50 % data drop probability of the no calking scheme and the link
utilization is improved 5~25% which varying with the offered load in a simple network.
Proc. SPIE. 6784, Network Architectures, Management, and Applications V
KEYWORDS: Superposition, Internet, Statistical analysis, Data modeling, Local area networks, Stochastic processes, Performance modeling, Broadband telecommunications, Network architectures, Process modeling
Understanding network traffic behavior is essential for all aspects of network design and operation, e.g.
component design, protocol design, provisioning, operations, administration and maintenance (OAM). A careful
study of traffic behavior can lead to improvements in underlying protocols to attain greater efficiencies and
higher performance. Many researches have shown that traffic in Ethernet and other networks, either in local or
wide area networks, exhibit properties of self-similarity. Several empirical studies on network traffic indicate
that this traffic is self-similar in nature. However, the network modeling methods used in current networks have
been primarily designed and analyzed under the assumption of the traditional Poisson arrival process. These
"Poisson-like" models suggest that the network traffic is smooth, which is inherently unable to capture the self-similar
characteristic of traffic. In this paper, after introduce the high performance broadband information
network (3Tnet) of China, an aggregation model at access convergence router (ACR) is proposed and analyzed
in 3Tnet. We studied the impact of large-scale aggregation applied at the edge of 3Tnet in terms of the self-similarity
level observed at the output traffic in presence of self-similar input traffic. Two formulas were
presented to describe the changes of Hurst parameter. Using OPNET software simulator, changes of traffic
characteristics after large-scale aggregation in 3Tnet was extensive studied. The theoretic analysis results were
consistent with the simulation results.
The explosion of Internet traffic has brought about an acute need for high-performance networks. The
bandwidth available on a single fiber has increased dramatically by the wavelength division multiplexing (WDM)
technologies. How to use the huge bandwidth flexibly and efficiently is one of the hot topics of optical networks.
It is high time that the high-performance switches/routers should be designed. All-optical switching network is a
networking platform with effective and agile utilization of the available optical bandwidth. Some promising
optical switching networks, such as optical packet switched, optical burst switched, and optical label switched
networks are proposed. The benefit of these networks compared to the existing optical WDM networks rises
from the higher network utilization at sub-wavelength granularity and from the supporting of more various
services. However, there are still a lot of challenges. One challenge of them is contention. Due to the fact that the
viable optical random access memory is not available in the optical domain so far, there exists a real possibility
that packets may contend with one another at a switching node. In this paper, a novel node architecture called
packet calking switch is proposed for all-optical switching networks. The proposed architecture is accompanied
by a signaling protocol for packet-based traffic handling. This proposed node architecture is introduced into a
simple network and a mesh network through simulation. The simulation results show that it is suitable for
prioritized packet transmission. And it is more cost-effective than the existing node architectures because it
requires much smaller optical switches and wavelength conversion to achieve nearly the same packet drop
performance as the node configured partial wavelength conversion.
With fiber being cheaper and cheaper, the core fiber bandwidth utilization is not the key factor of the network, how to use the huge bandwidth flexibly and efficiently is one of the hot topics of optical networks. Optical burst switching (OBS) is the best choice to statistically use the optical resources, OBS based transparent optical network attracting attentions. We proposed an integrated policy by using dual fiber links server model along with traffic spacing mechanism (TSM) by address differentiating and transmitting those traffics between adjacent nodes by IP directly, the others by OBS mechanism. The theoretical results show that this method can improve network performance and be practically used in fields.