Network-Wide Configuration Synthesis

Abstract

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.

Network configuration synthesis with abstract topologies

“…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].…”

“…The spine routers connect to the Internet through neighbors N [1][2]. The ToR routers attach to a set of servers ("a rack") that host services with address prefixes P [1][2][3][4][5][6][7][8].…”

Reachability Analysis for AWS-Based Networks

“…Related Work. Several previous tools using automated theorem proving have been developed in an effort to answer questions about software defined networks (SDNs) [1,2,5,12,13,16,19,25]. Similar to our approach, these tools reduce the problems to automated reasoning engines.…”

“…In some cases, they employ overapproximative static analysis [18,19]. In other cases, they use general purpose reasoning engines such as Datalog [12,15], BDD [1], SMT [5,16], and SAT Solvers [2,25]. VeriCon [2], NICE [8], and VeriFlow [19] verify network invariants by analyzing software-defined-network (SDN) programs, with the former two applying formal software verification techniques, and the latter using static analysis to split routes into equivalence classes.…”

“…Anteater performs SAT-based bounded model checking [4], while ConfigChecker uses BDD-based fixed-point model checking [7]. Previous work has applied Datalog to reachability analysis in either software or network contexts [12][13][14]24]. The approach used in Batfish [13,24] and SyNET [12] is similar to our Datalog approach; they allow users to express general queries about whole-network reachability properties using an expressive logic language.…”