Don't mind the gap: Bridging network-wide objectives and device-level configurations

Beckett, Ryan; Mahajan, Ratul; Millstein, Todd; Padhye, Jitendra; Walker, David

doi:10.1145/3371934.3371965

Cited by 38 publications

(86 citation statements)

References 8 publications

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“…The literature in this field is vast and includes BGP configuration checking (e.g., [7], [44]- [51]), ACL misconfiguration detection (e.g., [52], [53]), firewall checking (e.g., [17], [18], [21], [54]), SDN verification (e.g., [20], [23], [55], [56]), testing (e.g., [2], [57]- [60]), debugging (e.g., [61], [62]), differential analysis (e.g., [63]), concurrency analysis (e.g [64], [65]), automatic repair (e.g., [66]- [68]), synthesis (e.g. [69]- [71]), programming languages (e.g. [72]- [76]), safe network updates (e.g., [77]- [80]), data plane checking (e.g., [10], [11], [16], [25]), real-time checkers [12], [14], [30], [81], and more general network analyses (e.g., [6], [8], [9], [19], [82], [83]) together with suitable levels of abstractions (e.g., [84], [85]).…”

Section: E Discussion: Importance Of Empty Pecsmentioning

confidence: 99%

A Precise and Expressive Lattice-theoretical Framework for Efficient Network Verification

Horn

Kheradmand

Prasad

2019

2019 IEEE 27th International Conference on Network Protocols (ICNP)

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Network verification promises to detect errors, such as black holes and forwarding loops, by logically analyzing the control or data plane. To do so efficiently, the state-of-the-art (e.g., Veriflow) partitions packet headers with identical forwarding behavior into the same packet equivalence class (PEC).Recently, Yang and Lam showed how to construct the minimal set of PECs, called atomic predicates. Their construction uses Binary Decision Diagrams (BDDs). However, BDDs have been shown to incur significant overhead per packet header bit, performing poorly when analyzing large-scale data centers. The overhead of atomic predicates prompted ddNF to devise a specialized data structure of Ternary Bit Vectors (TBV) instead.However, TBVs are strictly less expressive than BDDs. Moreover, unlike atomic predicates, ddNF's set of PECs is not minimal. We show that ddNF's non-minimality is due to empty PECs. In addition, empty PECs are shown to trigger wrong analysis results. This reveals an inherent tension between precision, expressiveness and performance in formal network verification.Our paper resolves this tension through a new latticetheoretical PEC-construction algorithm, #PEC, that advances the field as follows: (i) #PEC can encode more kinds of forwarding rules (e.g., ip-tables) than ddNF and Veriflow, (ii) #PEC verifies a wider class of errors (e.g., shadowed rules) than ddNF, and (iii) on a broad range of real-world datasets, #PEC is 10× faster than atomic predicates. By achieving precision, expressiveness and performance, this paper answers a longstanding quest that has spanned three generations of formal network analysis techniques.

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Section: E Discussion: Importance Of Empty Pecsmentioning

confidence: 99%

A Precise and Expressive Lattice-theoretical Framework for Efficient Network Verification

Horn

Kheradmand

Prasad

2019

2019 IEEE 27th International Conference on Network Protocols (ICNP)

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“…Network configuration synthesis. Propane [45] and Genesis [19] also produce network-wide configurations out of routing requirements. Unlike our approach, however, Propane only supports BGP and Genesis only supports static routes.…”

Section: Related Workmentioning

confidence: 99%

Network-Wide Configuration Synthesis

El-Hassany

Tsankov

Vanbever

et al. 2017

Lecture Notes in Computer Science

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Computer networks are hard to manage. Given a set of highlevel requirements (e.g., reachability, security), operators have to manually figure out the individual configuration of potentially hundreds of devices running complex distributed protocols so that they, collectively, compute a compatible forwarding state. Not surprisingly, operators often make mistakes which lead to downtimes. To address this problem, we present a novel synthesis approach that automatically computes correct network configurations that comply with the operator's requirements. We capture the behavior of existing routers along with the distributed protocols they run in stratified Datalog. Our key insight is to reduce the problem of finding correct input configurations to the task of synthesizing inputs for a stratified Datalog program. To solve this synthesis task, we introduce a new algorithm that synthesizes inputs for stratified Datalog programs. This algorithm is applicable beyond the domain of networks. We leverage our synthesis algorithm to construct the first network-wide configuration synthesis system, called SyNET, that support multiple interacting routing protocols (OSPF and BGP) and static routes. We show that our system is practical and can infer correct input configurations, in a reasonable amount time, for networks of realistic size (> 50 routers) that forward packets for multiple traffic classes.

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“…The boxes denote routers. Using terminology for fat tree networks [3], S [1][2] are spine routers, A [1][2][3][4][5][6][7][8] are aggregation routers, 3 and T [1][2][3][4][5][6][7][8] are top-of-rack (ToR) routers. The spine routers connect to the Internet through neighbors N [1][2].…”

Section: Motivationmentioning

confidence: 99%

Network configuration synthesis with abstract topologies

Beckett

Mahajan

Millstein

et al. 2017

Proceedings of the 38th ACM SIGPLAN Conference on Programming Language Design and Implementation

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We develop Propane/AT, a system to synthesize provablycorrect BGP (border gateway protocol) configurations for large, evolving networks from high-level specifications of topology, routing policy, and fault-tolerance requirements. Propane/AT is based on new abstractions for capturing parameterized network topologies and their evolution, and algorithms to analyze the impact of topology and routing policy on fault tolerance. Our algorithms operate entirely on abstract topologies. We prove that the properties established by our analyses hold for every concrete instantiation of the given abstract topology. Propane/AT also guarantees that only incremental changes to existing device configurations are required when the network evolves to add or remove devices and links. Our experiments with real-world topologies and policies show that our abstractions and algorithms are effective, and that, for large networks, Propane/AT synthesizes configurations two orders of magnitude faster than systems that operate on concrete topologies.

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Don't mind the gap: Bridging network-wide objectives and device-level configurations

Cited by 38 publications

References 8 publications

A Precise and Expressive Lattice-theoretical Framework for Efficient Network Verification

A Precise and Expressive Lattice-theoretical Framework for Efficient Network Verification

Network-Wide Configuration Synthesis

Network configuration synthesis with abstract topologies

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