Multicast traffic aggregation in MPLS-based VPN networks

This article gives an overview of the current practical approaches under study for a scalable implementation of multicast in layer 2 and 3 VPNs over an IP-MPLS multiservice network. These proposals are based on a well-known technique: the aggregation of traffic into shared trees to manage the forwarding state vs. bandwidth saving trade-off. This sort of traffic engineering mechanism requires methods to estimate the resources needed to set up a multicast shared tree for a set of VPNs. The methodology proposed in this article consists of studying the effect of aggregation obtained by random shared tree allocation on a reference model of a representative network scenario.Publicad

Traffic Control in Packet Switched Networks

This thesis examines traffic control options available in two existing routing solutions in packet-switched networks. The first solution is the shortest path hop-by-hop routing deployed with the OSPF or IS-IS routing protocol and the IP forwarding protocol. This is the initially deployed and still the most popular routing solution in the Internet. The second solution is explicit routing implemented with the RSVP-TE or CR-LDP signalling protocol and the MPLS forwarding protocol. This is the latest solution to have become widely deployed in the Internet. The thesis analyses the limitations of the two routing solutions as tools for traffic control and yields new insights that can guide the analysis and design of protocols involved in the process. A set of recommendations for modifications of the existing protocols is provided which would allow for a range of new traffic control approaches to be deployed in packet-switched networks. For future routing solutions which comply with the proposed recommendations two new algorithms are presented in the thesis. They are called the Link Mask Topology (LMT) algorithm, and the Link Cost Topology (LCT) algorithm. The two algorithms define a set of routing topologies and assign network traffic to routes available in these topologies aiming to simultaneously achieve high network throughput and fair resource allocation. While there are similarities in the operation of the two algorithms, their applicability is different as they allocate resources to multiple paths between two network nodes which are available in the defined routing topologies according to a different rule set. The LMT algorithm directs traffic sent between any pair of network nodes to a single route. The LCT algorithm directs traffic sent between a pair of network nodes to a number of routes. The performance of the two proposed algorithms is evaluated in the thesis with calculations comparing them to the shortest path routing algorithm in a number of test cases. The test results demonstrate the potentials of the two proposed algorithms in improving the performance of networks which employ shortest path routing

On forwarding state control in VPN multicast based on MPLS multipoint LSPs

This work is at: 2012 IEEE 13th International Conference on High Performance Switching and Routing took place June 24-27,2012 in Belgrade, Serbia. Web to event: http://hpsr2012.etf.bg.ac.rs/index.phpThe demand for multicast-capable VPN services, like Virtual Private LAN Service (VPLS), has grown quickly in the last years. In order to save bandwidth, MPLS point-to-multipoint LSPs could be used, but the VPN-specific state information to be handled inside the network may exceed the capacity of core nodes. A well-known solution for this is to aggregate the multicast/broadcast traffic of multiple VPNs into shared p2mp LSP trees. In shared trees, although some bandwidth is wasted because a fraction of the packets are delivered to non-member leaves (either not in the VPN broadcast or multicast group), there is wide working range where a good state vs. bandwidth trade-off is achieved. In this paper we enhance and improve previous works that analyze this trade-off. We propose new techniques for multicast traffic aggregation of VPNs in MPLS-based networks, with the objective of observing the behavior of the aggregation philosophy for different aggregation degrees, which should be very useful for network design and deployment purposes. We assess the aggregation heuristics over different reference networks and VPN geographic distributions. Simulations give a quantitative indication of the relevance of intelligent aggregation, of geographical distribution and group sizes.The work described in this paper was carried out with the support of MEDIANET PRICIT 2009/TIC-1468, from the Community of Madrid; and Fundación Carolina, Spain.Publicad

Topological Design of Multiple Virtual Private Networks UTILIZING SINK-TREE PATHS

With the deployment of MultiProtocol Label Switching (MPLS) over a core backbone networks, it is possible for a service provider to built Virtual Private Networks (VPNs) supporting various classes of services with QoS guarantees. Efficiently mapping the logical layout of multiple VPNs over a service provider network is a challenging traffic engineering problem. The use of sink-tree (multipoint-to-point) routing paths in a MPLS network makes the VPN design problem different from traditional design approaches where a full-mesh of point-to-point paths is often the choice. The clear benefits of using sink-tree paths are the reduction in the number of label switch paths and bandwidth savings due to larger granularities of bandwidth aggregation within the network. In this thesis, the design of multiple VPNs over a MPLS-like infrastructure network, using sink-tree routing, is formulated as a mixed integer programming problem to simultaneously find a set of VPN logical topologies and their dimensions to carry multi-service, multi-hour traffic from various customers. Such a problem formulation yields a NP-hard complexity. A heuristic path selection algorithm is proposed here to scale the VPN design problem by choosing a small-but-good candidate set of feasible sink-tree paths over which the optimal routes and capacity assignments are determined. The proposed heuristic has clearly shown to speed up the optimization process and the solution can be obtained within a reasonable time for a realistic-size network. Nevertheless, when a large number of VPNs are being layout simultaneously, a standard optimization approach has a limited scalability. Here, the heuristics termed the Minimum-Capacity Sink-Tree Assignment (MCSTA) algorithm proposed to approximate the optimal bandwidth and sink-tree route assignment for multiple VPNs within a polynomial computational time. Numerical results demonstrate the MCSTA algorithm yields a good solution within a small error and sometimes yields the exact solution. Lastly, the proposed VPN design models and solution algorithms are extended for multipoint traffic demand including multipoint-to-point and broadcasting connections

Signalling of Point to Multipoint Trees in Metro Ethernet and Core Networks

Diplomityössä tutustuttiin IPTV-kanavien siirtoon Core-verkosta MetroEthernet-verkon asiakasta lähinnä olevalle laidalle. Tavoitteena oli kehittää nopeampi ratkaisu monilähetyspuiden konfigurointiin laitevalmistajan toteuttamilla protokollilla. Nykyinen ratkaisu, jossa käytetään Resource reSerVation Protocol:ia MultiProtocol Label Switching-tunneleiden signaloimiseen, Internet Group Management Protocol Snooping:ia halukkaiden vastaanottajien kartoittamiseen sekä Protocol Independent Multicast-Source Specific Multicast:ia runkoverkon monilähetykseen on liian työläs. Uudet ratkaisut, joissa yhdistellään RSVP:tä, point-to-multipoint RSVP:tä, Fast ReRoutea ja PIM-SSM:ia testataan TeliaSoneran tietoverkkolaboratoriossa. Tulosten perusteella ei voida sanoa paljoa varmasti, mutta FRR ME-verkossa vaikuttaa helppokäyttöiseltä ja toimivalta ratkaisulta. Lisäksi P2MP RSVP-TE herätti toiveita nopeammin vikatilanteista toipuvasta monilähetysratkaisusta runkoverkosta, kunhan ilmenneiden vikojen syyt saadaan selville.This master's thesis studies the distribution of IPTV channels from a core network to the edges of a MetroEthernet network. The goal is to find a faster solution for configuring multicast trees using protocols implemented by vendors. The current solution which uses Resource reSerVation Protocol for signalling MultiProtocol Label Switched tunnels, Internet Group Management Protocol Snooping for mapping receivers and Protocol Independent Multicast-Source Specific Multicast for core multicast creates too much work. The new solutions combine RSVP, point-to-multipoint RSVP, Fast ReRoute and PIM-SSM and they are tested in the TeliaSonera networking laboratory. Based on test results there is not much certainty about many things but it can be said that FRR seems to be working well and it is easy to use. Furthermore, P2MP RSVP seemed promising for the core network with faster convergence times in failure cases than PIM-SSM. However, there are few problems to be solved before the protocol is ready for use in the production network

Quality of Service over Specific Link Layers: state of the art report

The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service