The Internet is a collection of interconnected Autonomous Systems (ASes) that use the Border Gateway Protocol (BGP) to exchange reachability information. In this regard, BGP stability and scalability in the inter-domain scope have been matters of major concern for many years, and network engineers have been applying several techniques to cope with these issues. BGP is also used intra-domain (internal BGP - iBGP), to disseminate reachability information inside each AS, and works together with the Interior Gateway Protocols (IGPs) such as OSPF or IS-IS, to build routing tables. Route reflection is a widely adopted technique to tackle BGP scalability in the intra-domain scope, and choosing which routers will play the reflector role and which BGP sessions will be established among reflectors and clients (i.e. the routers which are not elected as reflectors), building an overlay of iBGP sessions, is known as the iBGP overlay design problem. The design of an optimal iBGP overlay is known to be a NP-Hard problem, and we proposed solutions for pure IP networks (i.e. best effort traffic forwarding) in our previous work. However, most Internet providers implement their backbones by combining IP routing with MPLS (Multiprotocol Label Switching) for QoS-aware traffic forwarding. MPLS forwarding incorporates traffic engineering and more efficient failover mechanisms; under this traffic forwarding paradigm, the design of traffic-engineered Label Switched Paths (LSPs, also referred as MPLS tunnels) shall be combined with the aforementioned iBGP overlay design. The present work introduces a coordinated design of both the iBGP overlay and the IP/MPLS substrates. Our contribution is the proposal of an optimal and resilient topology design for an IP/MPLS Internet backbone, which takes advantage of traffic engineering features to optimize the demands, while guaranteeing iBGP overlay optimality. We present a complete solution for a real world scenario, and we study the scalability of the solution for synthetic topologies, achieving encouraging results.

互联网是使用边界网关协议 (BGP) 交换可达性信息的互连自治系统 (AS) 的集合。在这方面，域间范围内的 BGP 稳定性和可扩展性多年来一直是主要关注的问题，网络工程师一直在应用多种技术来应对这些问题。BGP 还用于域内（内部 BGP - iBGP），在每个 AS 内部传播可达性信息，并与 OSPF 或 IS-IS 等内部网关协议 (IGP) 一起构建路由表。路由反射是一种广泛采用的技术，用于解决域内范围内的 BGP 可扩展性，并选择哪些路由器将扮演反射器角色以及将在反射器和客户端之间建立哪些 BGP 会话（即 没有被选为反射器的路由器），构建 iBGP 会话的覆盖，被称为 iBGP 覆盖设计问题。已知最佳 iBGP 覆盖的设计是一个 NP-Hard 问题，我们在之前的工作中为纯 IP 网络（即尽力而为的流量转发）提出了解决方案。然而，大多数互联网提供商通过将 IP 路由与 MPLS（多协议标签交换）相结合来实现其骨干网，以实现 QoS 感知流量转发。MPLS 转发结合了流量工程和更有效的故障转移机制；在这种流量转发范式下，流量工程标签交换路径（LSP，也称为 MPLS 隧道）的设计应与上述 iBGP 重叠设计相结合。目前的工作介绍了 iBGP 覆盖和 IP/MPLS 基板的协调设计。我们的贡献是为 IP/MPLS 互联网骨干网提出了一种最优且有弹性的拓扑设计方案，它利用流量工程特性来优化需求，同时保证 iBGP 覆盖的最优性。我们为现实世界的场景提供了一个完整的解决方案，我们研究了合成拓扑解决方案的可扩展性，取得了令人鼓舞的结果。