The proof of AODV loop freedom

Zhou, Ming; Yang, Huabing; Zhang, Xingyuan; Wang, Jinshuang

doi:10.1109/wcsp.2009.5371479

Cited by 15 publications

(25 citation statements)

References 4 publications

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“…As mentioned before, AODV "uses destination sequence numbers to ensure loop freedom at all times" [19,Page 2]. Moreover, it has been "proven" at least twice that AODV is loop free [22,26].…”

Section: Proofs Based On Sequence Numbersmentioning

confidence: 99%

“…]. A RFC is authored by engineers and computer scientists in the form of a memorandum describing methods, behaviors, research, or innovations applicable to the working 4 In [26] the model is only given partially. 5 Again only snippets of the proofs can be found in [26].…”

Section: Ambiguities In the Aodv Rfcmentioning

confidence: 99%

“…1 A proof of loop freedom of AODV has been provided in [22]. Another, more recent proof is [26]. 2 It is therefore a common belief that the use of sequence numbers in this context guarantees loop freedom.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Sequence numbers do not guarantee loop freedom

Glabbeek¹,

Höfner²,

Tan³

et al. 2013

Proceedings of the 16th ACM International Conference on Modeling, Analysis &Amp; Simulation of Wireless and Mobile Systems

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In the area of mobile ad-hoc networks and wireless mesh networks, sequence numbers are often used in routing protocols to avoid routing loops. It is commonly stated in protocol specifications that sequence numbers are sufficient to guarantee loop freedom if they are monotonically increased over time. A classical example for the use of sequence numbers is the popular Ad hoc On-Demand Distance Vector (AODV) routing protocol. The loop freedom of AODV is not only a common belief, it has been claimed in the abstract of its RFC and at least two proofs have been proposed. AODV-based protocols such as AODVv2 (DYMO) and HWMP also claim loop freedom due to the same use of sequence numbers.In this paper we show that AODV is not a priori loop free; by this we counter the proposed proofs in the literature. In fact, loop freedom hinges on non-evident assumptions to be made when resolving ambiguities occurring in the RFC. Thus, monotonically increasing sequence numbers, by themselves, do not guarantee loop freedom.

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Section: Proofs Based On Sequence Numbersmentioning

confidence: 99%

Section: Ambiguities In the Aodv Rfcmentioning

confidence: 99%

See 1 more Smart Citation

Sequence numbers do not guarantee loop freedom

Glabbeek¹,

Höfner²,

Tan³

et al. 2013

Proceedings of the 16th ACM International Conference on Modeling, Analysis &Amp; Simulation of Wireless and Mobile Systems

View full text Add to dashboard Cite

show abstract

“…Analysis and proof for this property of AODV have been proposed in [7], [1] using different methods. According to the analysis in [7], to prove loop freedom, Property 2 below should be proved first. We can apply rely-guarantee rules to its proof similar to Property 1.…”

Section: Analyzing On Aodvmentioning

confidence: 99%

Formal Analysis of AODV Using Rely-Guarantee

Zhu

2013

2013 International Symposium on Theoretical Aspects of Software Engineering

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Mobile Ad-hoc Networks (MANETs) are increasingly deployed in infrastructureless scenarios. Routing protocol is a crucial solution for MANETs to establish network connections. This paper presents a formal description of the AODV routing protocol and analyzes its properties using relyguarantee method. In our approach the network is specified as a shared variable concurrent program, where communication is modelled by assignment on shared variables. Each parallel component of this program is a specification of route discovery process. The rely-guarantee method allows us to express and verify properties of the protocol on the basis of specifications of its constituent components.

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“…does not capture the full behaviour of the routing protocol; and[35] is based on a subset of AODV that does not cover the "intermediate route reply" feature, a source of loops. In[25] a draft of a new version of AODV is modelled, without intermediate route reply.…”

mentioning

confidence: 99%

A Timed Process Algebra for Wireless Networks with an Application in Routing

Bres

Glabbeek

Höfner

2016

Programming Languages and Systems

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This paper proposes a timed process algebra for wireless networks, an extension of the Algebra for Wireless Networks. It combines treatments of local broadcast, conditional unicast and data structures, which are essential features for the modelling of network protocols. In this framework we model and analyse the Ad hoc On-Demand Distance Vector routing protocol, and show that, contrary to claims in the literature, it fails to be loop free. We also present boundary conditions for a fix ensuring that the resulting protocol is indeed loop free.7 An expression p is guarded if each call of a process name X(exp 1 , . . . , exp n ) occurs with a subexpression [ϕ]q, [[var := exp]]q, α.q or unicast(dest, ms).q ◮ r of p.A Timed Process Algebra for Wireless Networks 7 A Language for Networks. We model network nodes in the context of a wireless mesh network by node expressions of the form ip : PP : R. Here ip ∈ IP is the address of the node, PP is a parallel process expression, and R ⊆ IP is the range of the node-the set of nodes that are currently within transmission range of ip.A partial network is then modelled by a parallel composition of node expressions, one for every node in the network, and a complete network is a partial network within an encapsulation operator [ ] that limits the communication of network nodes and the outside world to the receipt and the delivery of data packets to and from the application layer attached to the modelled protocol in the network nodes. This yields the following grammar for network expressions:M ::= ip : PP : R | M M . The Semantics of T-AWNAs mentioned in the introduction, the transmission of a message takes time.Since our main application assumes wireless links and node mobility, the packet delivery time varies. Hence we assume a minimum time that is required to send a message, as well as an optional extra transmission time. In T-AWN the values of these parameters are given for each type of sending separately: LB, LG, and LU, satisfying LB, LG, LU > 0, specify the minimum bound, in units of time, on the duration of a broadcast, groupcast and unicast transmission; the optional additional transmission times are denoted by ∆B, ∆G and ∆U, satisfying ∆B, ∆G, ∆U ≥ 0. Adding up these parameters (e.g. LB and ∆B) yields maximum transmission times. We allow any execution consistent with these parameters. For all other actions our processes can take we postulate execution times of 0.

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The proof of AODV loop freedom

Cited by 15 publications

References 4 publications

Sequence numbers do not guarantee loop freedom

Sequence numbers do not guarantee loop freedom

Formal Analysis of AODV Using Rely-Guarantee

A Timed Process Algebra for Wireless Networks with an Application in Routing

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