Loop-free alternates and not-via addresses: A proper combination for IP fast reroute?
Loop-free alternates and not-via addresses: A proper combination for IP fast reroute?
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DOI：
10.1016/j.comnet.2009.10.020
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发表时间：
2010-06
期刊：
影响因子：
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通讯作者：
M. Menth;Matthias Hartmann;Rüdiger Martin;T. Cicic;Amund Kvalbein
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文献类型：
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作者：
M. Menth;Matthias Hartmann;Rüdiger Martin;T. Cicic;Amund Kvalbein
IETF目前正在讨论IP网络的快速重路由机制（IP FRR）。IP FRR在网络元件故障的情况下加速恢复，并避免重新收敛期间的微环路。提出了几种机制。无环替代（LFA）很简单，但无法覆盖所有单个链路和节点故障。不通过地址可以防止这些故障，但更复杂，特别是，它们使用隧道技术来偏离备份流量。在IETF中，已经提出了将这两种机制联合收割机以合并它们的优点：简单性和完全故障覆盖。这项工作分析了LFA，并根据他们的能力进行分类。我们定性地比较了LFA和非通路地址，并为它们的组合应用开发了一个概念，以实现100%的单一故障覆盖率，同时尽可能使用简单的LFA。现有LFA的适用性取决于网络的弹性要求。我们研究了两种IP FRR方法的备份路径长度和链路利用率，并量化了非经由地址引起的解封装负载和路由表大小的增加。我们的结论是，这两种方法的组合使用没有优势相比，应用程序的非通过地址。
The IETF currently discusses fast reroute mechanisms for IP networks (IP FRR). IP FRR accelerates the recovery in case of network element failures and avoids micro-loops during re-convergence. Several mechanisms are proposed. Loop-free alternates (LFAs) are simple but cannot cover all single link and node failures. Not-via addresses can protect against these failures but are more complex, in particular, they use tunneling techniques to deviate backup traffic. In the IETF it has been proposed to combine both mechanisms to merge their advantages: simplicity and full failure coverage. This work analyzes LFAs and classifies them according to their abilities. We qualitatively compare LFAs and not-via addresses and develop a concept for their combined application to achieve 100% single failure coverage, while using simple LFAs wherever possible. The applicability of existing LFAs depends on the resilience requirements of the network. We study the backup path length and the link utilization for both IP FRR methods and quantify the decapsulation load and the increase of the routing table size caused by not-via addresses. We conclude that the combined usage of both methods has no advantage compared to the application of not-via addresses only.