Providing scalable NH-diverse iBGP route re-distribution to achieve sub-second switch-over time

The role of BGP inside an AS is to disseminate the routes learned from external peers to all routers of the AS. A straightforward, but not scalable, solution, is to resort to a full-mesh of iBGP sessions between the routers of the domain. Achieving scalability in the number of iBGP sessions is possible by using Route Reflectors (RR). Relying on a sparse iBGP graph using RRs however has a negative impact on routers’ ability to quickly switch to an alternate route in case of a failure. This stems from the fact that routers do not often know routes towards distinct next-hops, for any given prefix.In this paper, we propose a solution to build sparse iBGP topologies, where each BGP router learns two routes with distinct next-hops (NH) for each prefix. We qualify such iBGP topologies as NH-diverse. We propose to leverage the “best-external” option available on routers. By activating this option, and adding a limited number of iBGP sessions to the existing iBGP topology, we obtain NH-diverse iBGP topologies that scale, both in number of sessions and routing table sizes. We show that NH diversity enables to achieve sub-second switch-over time upon the failure of an ASBR or interdomain link. The scalability of our approach is confirmed by an evaluation on a research and a Service Provider network.     

Overview of measurement-based connection admission control methods in ATM networks

An overview is given of previously-proposed measurement-based connection admission control (CAC) methods. First we address requirements for CAC methods, and then provide a taxonomy for CAC methods. Measurement-based CAC methods are discussed in detail, classified according to the taxonomy, and compared against each other with respect to the requirements. We conclude that measurement-based CAC methods based on effective bandwidth and bufferless models are promising because they do not require complex hardware and are less dependent on assumptions regarding traffic than methods in which the effect of buffer is considered.     

Synthesis and properties of poly(organophosphazenes) electrolyte [NP(NHC6H5)2−x(NHC6H4SO3H-p)x]n

Poly(anilino sulphanic)phosphazene [NP(NHC₆H₅)_2–x (NHC₆H₄SO₃H) _x ] _n was prepared by the reaction between poly(anilino)phosphazene [NP(NHC₆H₅)₂] _n and sulphonic chloride (HSO₃Cl) in tetrachloroethane solvent. It was found that the glass transition temperature and conductivity of poly(anilino sulphanic)phosphazene increased with increasing value ofx. In addition, the storage power of the polymer withx=0.74 was determined and they were possible to charge by repitation of the use.     

Distributed virtual network topology control mechanism in GMPLS-based multiregion networks

This paper proposes a distributed virtual network topology (VNT) reconfiguration method for Internet Protocol over a wavelength-division-multiplexing network under dynamic traffic demand. We have developed a simple heuristic algorithm for calculating the VNT for distributed control. A generalized multiprotocol label switching (GMPLS)-based routing protocol has been developed. The VNT is quickly reconfigured by setting up and/or tearing down lightpaths using a GMPLS signaling protocol. Traffic demand is measured at the ingress node and advertised by the extended GMPLS routing protocol. Performance of the proposed method is investigated using variable traffic model.     

The reaction between poly(dichlorophosphazene) and epoxide compounds using Friedel-Crafts catalysts

The reaction between poly(dichlorophosphazene) and epichlorohydrin was carried out in tetrachloroethane using various Friedel-Crafts type catalysts. It was found that ferric chloride, FeCl₃, is the most suitable catalyst to transfer chlorine from poly(dichlorophosphazene) to CH in epoxide compounds. The molecular weight of the prepared product had decreased in comparison with that of poly(dichlorophosphazene); however, the products having the highest molecular weight were prepared with epifluorohydrin or 1,2-epoxy-3,3,3,-trichloropropane.     

Dynamic burst transfer time-slot-base network

This article proposes a new high-speed network architecture called dynamic burst transfer time-slot-base network (DBTN). The DBTN network is based on circuit-switched network technology. A routing tag is attached to a burst at an ingress edge node and the burst is self-routed in a DBTN network, the circuit of which is created dynamically by the routing tag. The routing tag, which is called time-slots-relay, consists of link identifiers from the ingress to the egress nodes and is used to create the circuit. Subsequent data is switched over the circuit being created in an on-the-fly fashion. Each link identifier is loaded into the address control memory (ACM) of each circuit switching node, and thereby the circuit to the destination is created dynamically. Subsequent user data follows immediately after the time-slots-relay and is sent over the established circuit. Thus short-lived fairly large data transfers such as WWW traffic are efficiently carried. A circuit between adjacent nodes is created and released dynamically so bandwidth efficiency is improved compared with conventional circuit-switched networks. Time division multiplexing of the circuit-switched network is utilized so there is no delay jitter or loss within a burst. We address the performance of DBTN switches and report the experimental system     

A simple bandwidth management strategy based on measurements ofinstantaneous virtual path utilization in ATM networks

A new connection admission control method based on actual virtual path traffic measurements is proposed to achieve high bandwidth efficiency for various types of traffic. The proposed method is based on the measurement of instantaneous virtual path utilization, which is defined as the total cell rate of the active virtual channels normalized by the virtual path capacity. A low-pass filter is used to determine the instantaneous virtual path utilization from crude measurements. A smoothing coefficient formula is derived as a function of the peak rate of the virtual channel. The residual bandwidth is derived from the maximum instantaneous utilization observed during a monitoring period. Simulation shows that the proposed method achieves statistical multiplexing gains of up to 80% of the limit possible with optimum control for similar traffic sources. It can be implemented with very simple hardware. The admission decision is simple: the requested bandwidth is compared with the residual bandwidth. This method is therefore well suited for practical asynchronous transfer mode switching systems     

Dynamic call admission control in ATM networks

The authors present dynamic call admission control using the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by users. Call acceptance is decided on the basis of online evaluation of the upper bound of cell loss probability, derived from the estimated distribution of the number of calls arriving. QOS (quality of service) standards can be guaranteed using this control when there is no estimation error. The control mechanism is effective when the number of call classes is large. It tolerates loose bandwidth enforcement and loose policing control, and dispenses with modeling of the arrival processes. Numerical examples demonstrate the effectiveness of this control, and implementation is also discussed     

Design of versatile academic infrastructure for multilayer network services

This paper describes the network design and configurations of the new Japanese academic infrastructure, called SINET3, which provides a rich variety of network services to more than 700 universities and research institutions. Since the start of full-scale operations in June 2007, the network has expanded its services to include multi-layer transfer services (IP, Ethernet, and layer-1), enriched virtual private network services (L3VPN, L2VPN, VPLS, and L1VPN), enhanced QoS services (packet-based and circuit-based), and brand-new layer-1 bandwidth-on-demand (BoD) services. This paper explains how the network provides these various network services on a single network platform by effectively configuring leading-edge networking components, such as high-performance IP routers, layer- 1 switches, and a BoD server. Evaluations of the network design and configurations confirmed that the networking functions were effectively coordinated. The procedures and techniques related to the configuration validation that covered all phases of the network design and construction are also presented.