| 1. |
- Bagula, Antoine B
(författare)
-
Hybrid IGP+MPLS routing in next generation IP networks : an online traffic engineering model
- 2005
-
Ingår i: QUALITY OF SERVICE IN MULTISERVICE IP NETWORKS, PROCEEDINGS. - 354024557X ; , s. 325-338
-
Konferensbidrag (refereegranskat)abstract
- Hybrid routing approaches which either combine the best of traditional IGP and MPLS routing or allow a smooth migration from traditional IGP routing to the newly proposed MPLS standard have scarcely been addressed by the IP community. This paper presents an on-line traffic engineering (TE) model which uses a hybrid routing approach to achieve efficient routing of flows in IP networks. The model assumes a network-design process where the IP flows are classified at the ingress of the network and handled differently into the core using a multiple metric routing mechanism leading to the logical separation of a physical network into two virtual networks: An IGP network carrying low bandwidth demanding (LBD) flows and an MPLS network where bandwidth-guaranteed tunnels are setup to route high bandwidth demanding (HBD) flows. The hybrid routing approach uses a route optimization model where (1) link weight optimization (LWO) is implemented in the IGP network to move the IP flows away from links that provide a high probability to become bottleneck for traffic engineering and (2) the MPLS network is engineered to minimize the interference among competing flows and route the traffic away from heavily loaded links. We show that a cost-based optimization framework can be used by an ISP to design simple and flexible routing approaches where different metrics reflecting the ISP ' s view of its TE objectives are deployed to improve the use and efficiency of a network. This is achieved through extensions to a mixed cost metric derived from the route optimization model. The IGP+MPLS routing approach is applied to compute paths for the traffic offered to a 15- and 50-node network. Preliminary simulation reveals performance improvements compared to both IGP and MPLS routing in terms of the routing optimality and the network reliability.
|
|
| 2. |
- Bagula, Antoine B
(författare)
-
Hybrid Routing in Next Generation IP Networks : QoS Routing Mechanisms and Network Control Strategies
- 2006
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Communication networks have evolved from circuit-switched and hop-by-hop routed systems into hybrid data/optical networks using the Internet as a common backbone carrying narrow- and broad-band traffic offered by a multitude of access networks. This data/optical backbone is built around a multi-technology/multi-protocol routing architecture which runs the IP protocols in a collapsed IP stack where ATM and SONET/SDH have been replaced by the suite of Generalized Multiprotocol Label Switching (GMPLS) protocols. A further evolution referred to as ``IP over Photons'' or ``All IP - All Optical'' is expected where ``redundant intermediate layers'' will be eliminated to run IP directly on top of optical cross-connects (OXCs) with the expectation of achieving savings on operation expenditures (OPEX) and capital expenditures (CAPEX). ``IP over Photons'' has been stalled by the immaturity in the control and data plane technologies leading to complex and time-consuming manual network planning and configurations which require a group of ``layer experts'' to operate and maintain a hybrid data/optical network. By making the status of each link and node of a data/optical network visible to a common control, GMPLS protocols have opened the way for automated operation and management allowing the different layers of an IP stack to be managed by a single network operator. GMPLS protocols provide the potential to make more efficient use of the IP backbone by having network management techniques such as Traffic Engineering (TE) and Network Engineering (NE), once the preserve of telecommunications, to be reinvented and deployed to effect different Quality of Service (QoS) requirements in the IP networks. NE moves bandwidth to where the traffic is offered to the network while TE moves traffic to where the bandwidth is available to achieve QoS agreements between the current and expected traffic and the available resources. However,several issues need to be resolved before TE and NE be effectively deployed in emerging and next generation IP networks. These include (1) the identification of QoS requirements of the different network layer interfaces of the emerging and next generation IP stack (2) the mapping of these QoS requirements into QoS routing mechanisms and network control strategies and (3) the deployment of these mechanisms and strategies within and beyond an Internet domain's boundaries to maximize the engineering and economic efficiency. Building upon different frameworks and research fields, this thesis revisits the issue of Traffic and Network Engineering (TE and NE) to present and evaluate the performance of different QoS routing mechanisms and network control strategies when deployed at different network layer interfaces of a hybrid data/optical network where an IP over MPLS network is layered above an MP λS/Fiber infrastructure. These include mechanisms and strategies to be deployed at the IP/MPLS, MPLS/MP λS and MP λS/Fiber network layer interfaces. The main contributions of this thesis are threefold. First we propose and compare the performance of hybrid routing approaches to be deployed in IP/MPLS networks by combining connectionless routing mechanisms used by classical IGP protocols and the connection oriented routing approach borrowed from MPLS. Second, we present QoS routing mechanisms and network control strategies to be deployed at the MPLS/MP λS network layer interface with a focus on contention-aware routing and inter-layer visibility to improve multi-layer optimality and resilience. Finally, we build upon fiber transmission characteristics to propose QoS routing mechanisms where the routing in the MPLS and MP λS layers is conducted by Photonic characteristics of the fiber such as the availability of the physical link and its failure risk group probability.
|
|
| 3. |
- Bagula, Antoine B
(författare)
-
Hybrid routing in next generation IP networks
- 2006
-
Ingår i: Computer Communications. - : Elsevier BV. - 0140-3664 .- 1873-703X. ; 29:7, s. 879-892
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a hybrid approach for routing flows in IP networks to achieve an optimal network configuration maximising bandwidth usage (optimality), minimising re-routing upon failure (reliability) and reducing the signalling overheads resulting from a full IP tunnelling (scalability). We formulate the routing of flows in IP networks as a service differentiated model where the IP flows are classified into high bandwidth demanding (LBD) and low bandwidth demanding (LBD) flows at the ingress of the network and handled differently into the core using a hybrid IGP+MPLS approach where the LBD flows are routed over the existing IGP paths while the HBD flows are carried over MPLS bandwidth-guaranteed tunnels. This model can be deployed in heterogenous network environments where HBD flows carrying real-time traffic and LBD flows transporting best-effort traffic are handled differently over a common transport network implementing traffic prioritization in response to natural or man-made emergencies. We consider the routing of flows within an IP domain's boundaries and evaluate the efficiency of the new routing approach under uniform and bursty traffic profiles. We apply the routing approach to compute paths for the traffic offered to a 20- and 50-node test networks. Simulation reveals that the hybrid routing approach outperforms both IGP and MPLS routing under the network conditions and test network models considered.
|
|
| 4. |
- Bagula, Antoine B.
(författare)
-
Hybride traffic engineering : from constraint shortest path first to least path interference
- 2005
-
Ingår i: South African Computer Journal. - 1015-7999. ; 34, s. 2-10
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new approach for routing flows in IP networks. The approach referred to as the Least Path Interference (LPI) is based on a route optimisation model which (1) moves the traffic away from path interfering links (the path interference quantifying the network reliability) to re-route fewer flows upon link failure and (2) maximises the link congestion distance (quantifying the network optimality) to reject fewer flows under congestion. LPI implements a hybrid traffic engineering model combining offline estimation of the path interference and online path selection. LPI is based on a simple path selection model where no changes to the traditional routing algorithms are required besides designing a new mixed cost metric to combine reliability and optimality. The Least Path Interfering Algorithm (LPIA ); a routing algorithm derived from LPI is applied to compute paths for the traffic offered to a 20- and 50-node networks. Simulation reveals (1) performance improvements compared to Open Shortest Path First (OSPF) and Constraint Shortest Path First (CSPF) routing in terms of routing optimality and network reliability and (2) the same performance as the recently proposed Least Interference Optimisation Algorithm (LIOA) algorithm with less signalling overheads.
|
|
| 5. |
- Bagula, Antoine B.
(författare)
-
On achieveing bandwidth-aware LSP/lambda SP multiplexing/separation in multi-layer networks
- 2007
-
Ingår i: IEEE Journal on Selected Areas in Communications. - 0733-8716 .- 1558-0008. ; 25:5, s. 987-1000
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new Traffic engineering (TE) model which is based on QoS rerouting and uses hybrid resilience to improve the recovery performance of multi-layer networks where an MPLS network is layered above an MP lambda S network. We formulate the rerouting of the LSPs/lambda SPs as a multi-constrained problem and use its polynomial reduction to find a heuristic solution that can be implemented by standardized constraint-based routing algorithms. This heuristic solution uses a cost-based routing optimization to achieve different network configurations which multiplex/separate bandwidth-aware LSPs/lambda SPs on the network links. We formulate the resilience upon failure as a multi-objective problem consisting of finding a resilience strategy that minimizes recovery operation time and maximizes the LSP/lambda SP restorability. A solution to this problem is proposed where a hybrid resilience framework is used to achieve restoration in the MPLS layer to complement path switching in the MP lambda S layer. We evaluate the performance of the TE model when rerouting the tunnels carrying the traffic offered to a 23- and 31-node networks. Simulation reveals that the hybrid resilience model performs better than classical recovery mechanisms in terms of restorability, quality of rerouting paths and rerouting; stability.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Bagula, Antoine B., et al.
(författare)
-
On achieving LSP/λSP multiplexing/separation in converged data/optical networks
- 2006
-
Ingår i: Journal of Optical Networking. - 1536-5379. ; 5:4, s. 280-292
-
Tidskriftsartikel (refereegranskat)abstract
- We revisit the concept of path multiplexing/separation and its impact on the recovery performance in converged data/optical networks. We formulate the rerouting of failed tunnels as a path set finding problem subject to quality of service (QoS) and network control constraints. We solve this problem using a heuristic solution that is based on a cost metric that (1) uses congestion in the optical layer to guide routing decisions and (2) engineers converged multiprotocol label switching networks and multiprotocol lambda switching (MPLS/MPλ S) networks to achieve path multiplexing/separation when rerouting the label switched paths (LSPs) and the lambda switched paths (λ SPs). We apply this solution to achieve multilayer resilience using a mixed scheme where protection switching is complemented by path restoration. We evaluate the performance of this scheme when rerouting the tunnels carrying the traffic offered to 15- and 23-node networks. Simulation reveals performance improvements of the proposed scheme when compared with classical recovery schemes that use several other existing algorithms such as minimum hop algorithm (MHA), open shortest path first (OSPF), and widest shortest path (WSP) in terms of the rerouting efficiency and bandwidth usage optimization.
|
|
| 9. |
- Bagula, Antoine B, et al.
(författare)
-
On the relevance of using gene expression programming in destination-based traffic engineering
- 2005
-
Ingår i: Computational Intelligence and Security. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 224-229
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper revisits the problem of Traffic Engineering (TE) to assess the relevance of using Gene Expression Programming (GEP) as a new fine-tuning algorithm in destination-based TE. We present a new TE scheme where link weights are computed using GEP and used as fine-tuning parameters in destination-based path selection. We apply the newly proposed TE scheme to compute the routing paths for the traffic offered to a 23- and 30-node test networks under different traffic conditions and differentiated services situations. We evaluate the performance achieved by the GEP algorithm compared to a memetic and the Open Shortest Path First (OSPF) algorithms in a simulated routing environment using the NS packet level simulator. Preliminary results reveal the relative efficiency of GEP compared to the memetic algorithm and OSPF routing.
|
|
| 10. |
|
|
