Transiently Secure Network Updates
Transiently Secure Network Updates
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DOI：
10.1145/2896377.2901476
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Arne Ludwig;S. Dudycz;Matthias Rost;S. Schmid
中科院分区：
文献类型：
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作者：
Arne Ludwig;S. Dudycz;Matthias Rost;S. Schmid
计算机网络已经成为重要的基础设施。特别是在数据中心这样的共享环境中，任何时候都要保证正确、一致和安全的网络操作，甚至在路由策略更新期间也是如此。特别是，在任何时间点上都不应该让数据包绕过安全关键的路径点（例如防火墙或IDS）或沿着循环转发。本文研究了如何以瞬时一致的方式改变路由策略的问题。暂态一致性网络更新被认为是一种快速且资源高效的替代方案，可以替代每包一致性更新。我们的主要结果是一个消极的：我们表明，在一些设置中，路点强制和循环自由这两个基本属性不能同时得到满足。更糟糕的是，我们严格地证明了决定一个路点强制、无环路的网络更新计划是否存在是np困难的。这些结果适用于文献中使用的两种循环自由：强循环自由和松弛循环自由。本文还提出了优化的精确混合整数程序来计算最优更新计划。我们报告了广泛的模拟结果，并开始讨论需要确保多个路点（也称为服务链）的场景。
Computer networks have become a critical infrastructure. Especially in shared environments such as datacenters it is important that a correct, consistent and secure network operation is guaranteed at any time, even during routing policy updates. In particular, at no point in time should it be possible for packets to bypass security critical waypoints~(such as a firewall or IDS) or to be forwarded along loops. This paper studies the problem of how to change routing policies in a transiently consistent manner. Transiently consistent network updates have been proposed as a fast and resource efficient alternative to per-packet consistent updates. Our main result is a negative one: we show that there are settings where the two basic properties waypoint enforcement and loop-freedom cannot be satisfied simultaneously. Even worse, we rigorously prove that deciding whether a waypoint enforcing, loop-free network update schedule exists is NP-hard. These results hold for both kinds of loop-freedom used in the literature: strong and relaxed loop-freedom. This paper also presents optimized, exact mixed integer programs to compute optimal update schedules. We report on extensive simulation results and initiate the discussion of scenarios where multiple waypoints need to be ensured (also known as service chains).