Survivable Design of Multi-Domain Multi-Layer Backbone Networks

可靠的通信网络和服务对现代社会至关重要。我们的重点是评估和提高主干网的可靠性，这些主干网承载着城域内、跨区域或国家、或跨大陆的聚合用户通信流量。目前，骨干网在技术上采用层次结构，由多层组成。在上层，基于IP （Internet Protocol）的用户流量占主导地位，由数据包承载。许多IP业务需要一定的服务质量，包括服务可靠性，因此作为IP流而不是单独的数据包进行传输。上层的IP链路在下层以可重构电路的形式实现，如波分复用（WDM）网络中的光路。对IP流的保护可以通过在上层提供备份IP路径，或在下层提供备份光路，或两者的组合来完成。虽然单层网络和业务可靠性已经被广泛研究了二十年，但在多层网络环境中，许多重要问题仍然没有得到解决，例如，当IP链路与下层电路的映射复杂，导致IP链路故障不独立时，如何量化IP流的可用性，如何找到网络故障或攻击的位置并隔离网络故障或攻击，如何防止多重网络故障或攻击等。独立于技术层次结构，骨干网也作为多个管理域或由不同的网络运营商管理。对于终端用户来说，最重要的是端到端的业务可靠性，而不是网络链路或网段的可靠性。因此，跨多个域的保护设计和协调非常重要，然而，由于跨域的信息共享有限以及网络运营商之间有时存在竞争关系，这也非常具有挑战性。本课题将探讨多域多层网络环境下服务保护的设计问题。

Reliable communication networks and services are critical to modern societies. Our focus is to assess and improve reliability of backbone networks carrying aggregated user communication traffic within a metropolitan area, or across a region or country, or among continents. Currently, backbone networks are technologically organized in a hierarchy, which consists of multiple layers. At an upper layer, Internet Protocol (IP)-based user traffic is dominant, carried by data packets. Many IP services require certain quality of service, including service reliability, and thus are carried as IP flows, as opposed to individual packets. IP links in the upper layer are implemented in lower layers as reconfigurable circuits, such as lightpaths in Wavelength Division Multiplexing (WDM) networks. Protections to IP flows can be accomplished by providing backup IP paths at the upper layer, or providing backup lightpaths at lower layers, or a combination of both. Although single layer network and service reliability has been extensively studies for two decades, in a multi-layer network environment, a lot of important problems remain unsolved, for example, how to quantify the availability of IP flows when IP-link failures are not independent as a result of complicated mappings of IP links to lower-layer circuits, how to find the locations and then isolate network faults or attacks, how to protect against multiple network failures or attacks, etc. Independent of technological hierarchy, backbone networks also are administered as multiple administration domains or by different network operators. For end users, it is end-to-end service reliability that matters, not the reliability of network links or segments. Therefore, design and coordination of protections across multiple domains are important, however, also very challenging due to limited information sharing across domains and sometime competitive relations among network operators. This proposed project will investigate the design issues of service protection in a multi-domain multi-layer network environment.