Modeling complexity of enterprise routing design

Abstract

Enterprise networks often have complex routing designs given the need to meet a wide set of resiliency, security and routing policies. In this paper, we take the position that minimizing design complexity must be an explicit objective of routing design. We take a first step to this end by presenting a systematic approach for modeling and reasoning about complexity in enterprise routing design. We make three contributions. First, we present a framework for precisely defining objectives of routing design, and for reasoning about how a combination of routing design primitives (e.g. routing instances, static routes, and route filters etc.) will meet the objectives. Second, we show that it is feasible to quantitatively measure the complexity of a routing design by modeling individual routing design primitives, and leveraging configuration complexity metrics [5]. Our approach helps understand how individual design choices made by operators impact configuration complexity, and can enable quantifying design complexity in the absence of configuration files. Third, we validate our model and demonstrate its utility through a longitudinal analysis of the evolution of the routing design of a large campus network over the last three years. We show how our models can enable comparison of the complexity of multiple routing designs that meet the same objective, guide operators in making design choices that can lower complexity, and enable what-if analysis to assess the potential impact of a configuration change on routing design complexity.

Minimizing network complexity through integrated top-down design

“…According to recent studies [7,31,32], these dependencies are directly linked to the operational cost as they require substantial manual effort to configure correctly in the initial implementation and manage in subsequent evolutions, and if not maintained properly, can lead to serious issues such as application performance degradation and security breaches.…”

“…To capture this insight in the design process, we leverage the abstraction of "policy groups" introduced by recent works [7,31] including our own for network modeling. A policy group abstracts the set of hosts that are (i) subject to the same reachability policy towards other hosts and (ii) have full reachability among themselves.…”

“…Recent research [7,22,31] and vendor documents [1,27] reveal that multiple, distinct routing designs are possible to meet the same set Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored.…”

Performance Analysis of Route Redistribution among Diverse Dynamic Routing Protocols based on OPNET Simulation

“…The border router may be configured to redistribute routes from one routing protocol to the other, and vice versa. The route redistribution is needed in case of company mergers, multiple departments managed by multiple network administrators, multi−vendor environment, and split of two independent routing domains [1][2]. The route redistribution has two main goals.…”

Towards test-driven software defined networking

“…For example, when an operator configures IGP weights, she indicates her preference for some paths over others, typically for traffic engineering purposes. In enterprise networks, operators often need to force traffic to pass through specific middle-boxes [7] or avoid some parts of the network [10]. For example, traffic to a server may always need to traverse a firewall.…”