Showing papers on "Static routing published in 2001"

Split multipath routing with maximally disjoint paths in ad hoc networks

Abstract: In recent years, routing has been the most focused area in ad hoc networks research On-demand routing in particular, is widely developed in bandwidth constrained mobile wireless ad hoc networks because of its effectiveness and efficiency Most proposed on-demand routing protocols however, build and rely on a single route for each data session Whenever there is a link disconnection on the active route, the routing protocol must perform a route recovery process In QoS routing for wired networks, multiple path routing is popularly used Multiple routes are however, constructed using link-state or distance vector algorithms which are not well-suited for ad hoc networks We propose an on-demand routing scheme called split multipath routing (SMR) that establishes and utilizes multiple routes of maximally disjoint paths Providing multiple routes helps minimizing route recovery process and control message overhead Our protocol uses a per-packet allocation scheme to distribute data packets into multiple paths of active sessions This traffic distribution efficiently utilizes available network resources and prevents nodes of the route from being congested in heavily loaded traffic situations We evaluate the performance of our scheme using extensive simulation

Maximum battery life routing to support ubiquitous mobile computing in wireless ad hoc networks

Abstract: Most ad hoc mobile devices today operate on batteries. Hence, power consumption becomes an important issue. To maximize the lifetime of ad hoc mobile networks, the power consumption rate of each node must be evenly distributed, and the overall transmission power for each connection request must be minimized. These two objectives cannot be satisfied simultaneously by employing routing algorithms proposed in previous work. We present a new power-aware routing protocol to satisfy these two constraints simultaneously; we also compare the performance of different types of power-related routing algorithms via simulation. Simulation results confirm the need to strike a balance in attaining service availability performance of the whole network vs. the lifetime of ad hoc mobile devices.

On inferring autonomous system relationships in the internet

Abstract: The Internet consists of rapidly increasing number of hosts interconnected by constantly evolving networks of links and routers. Interdomain routing in the Internet is coordinated by the Border Gateway Protocol (BGP). The BGP allows each autonomous system (AS) to choose its own administrative policy in selecting routes and propagating reachability information to others. These routing policies are constrained by the contractual commercial agreements between administrative domains. For example, an AS sets its policy so that it does not provide transit services between its providers. Such policies imply that AS relationships are an important aspect of the Internet structure. We propose an augmented AS graph representation that classifies AS relationships into customer-provider, peering, and sibling relationships. We classify the types of routes that can appear in BGP routing tables based on the relationships between the ASs in the path and present heuristic algorithms that infer AS relationships from BGP routing tables. The algorithms are tested on publicly available BGP routing tables. We verify our inference results with AT&T internal information on its relationship with neighboring ASs. As much as 99.1% of our inference results are confirmed by the AT&T internal information. We also verify our inferred sibling relationships with the information acquired from the WHOIS lookup service. More than half of our inferred sibling-to-sibling relationships are confirmed by the WHOIS lookup service. To the best of our knowledge, there has been no publicly available information about AS relationships and this is the first attempt in understanding and inferring AS relationships in the Internet. We show evidence that some routing table entries stem from router misconfigurations.

Energy efficient routing in wireless sensor networks

Abstract: Wireless sensor nodes can be deployed on a battlefield and organize themselves in a large-scale ad-hoc network. Traditional routing protocols do not take into account that a node contains only a limited energy supply. Optimal routing tries to maximize the duration over which the sensing task can be performed, but requires future knowledge. As this is unrealistic, we derive a practical guideline based on the energy histogram and develop a spectrum of new techniques to enhance the routing in sensor networks. Our first approach aggregates packet streams in a robust way, resulting in energy reductions of a factor 2 to 3. Second, we argue that a more uniform resource utilization can be obtained by shaping the traffic flow. Several techniques, which rely only on localized metrics are proposed and evaluated. We show that they can increase the network lifetime up to an extra 90% beyond the gains of our first approach.

Power-aware localized routing in wireless networks

Abstract: A cost aware metric for wireless networks based on remaining battery power at nodes was proposed for shortest-cost routing algorithms, assuming constant transmission power. Power-aware metrics, where transmission power depends on distance between nodes and corresponding shortest power algorithms were also proposed. We define a power-cost metric based on the combination of both node's lifetime and distance-based power metrics. We investigate some properties of power adjusted transmissions and show that, if additional nodes can be placed at desired locations between two nodes at distance d, the transmission power can be made linear in d as opposed to d/sup /spl alpha// dependence for /spl alpha/ /spl ges/ 2. This provides basis for power, cost, and power-cost localized routing algorithms where nodes make routing decisions solely on the basis, of location of their neighbors and destination. The power-aware routing algorithm attempts to minimize the total power needed to route a message between a source and a destination. The cost-aware routing algorithm is aimed at extending the battery's worst-case lifetime at each node. The combined power-cost localized routing algorithm attempts to minimize the total power needed and to avoid nodes with a short battery's remaining lifetime. We prove that the proposed localized power, cost, and power-cost efficient routing algorithms are loop-free and show their efficiency by experiments.

Delayed Internet routing convergence

Abstract: This paper examines the latency in Internet path failure, failover, and repair due to the convergence properties of interdomain routing. Unlike circuit-switched paths which exhibit failover on the order of milliseconds, our experimental measurements show that interdomain routers in the packet-switched Internet may take tens of minutes to reach a consistent view of the network topology after a fault. These delays stem from temporary routing table fluctuations formed during the operation of the border gateway protocol (BGP) path selection process on the Internet backbone routers. During these periods of delayed convergence, we show that end-to-end Internet paths will experience intermittent loss of connectivity, as well as increased packet loss and latency. We present a two-year study of Internet routing convergence through the experimental instrumentation of key portions of the Internet infrastructure, including both passive data collection and fault-injection machines at major Internet exchange points. Based on data from the injection and measurement of several hundred thousand interdomain routing faults, we describe several unexpected properties of convergence and show that the measured upper bound on Internet interdomain routing convergence delay is an order of magnitude slower than previously thought. Our analysis also shows that the upper theoretic computational bound on the number of router states and control messages exchanged during the process of BGP convergence is factorial with respect to the number of autonomous systems in the Internet. Finally, we demonstrate that much of the observed convergence delay stems from specific router vendor implementation decisions and ambiguity in the BGP specification.

The performance of query control schemes for the zone routing protocol

Abstract: In this paper, we study the performance of route query control mechanisms for the Zone Routing Protocol (ZRP) for ad hoc networks. ZRP proactively maintains routing information for a local neighborhood (routing zone), while reactively acquiring routes to destinations beyond the routing zone. This hybrid routing approach can be more efficient than traditional routing schemes. However, without proper query control techniques, the ZRP cannot provide the expected reduction in the control traffic.Our proposed query control schemes exploit the structure of the routing zone to provide enhanced detection and prevention of overlapping queries. These techniques can be applied to single- or multiple-channel ad hoc networks to improve both the delay and control traffic performance of ZRP. Our query control mechanisms allow ZRP to provide routes to all accessible network nodes, with less control traffic than purely proactive link state or purely reactive route discovery, and with less delay than conventional flood searching.

System and method to provide routing control of information over networks

Abstract: A system and method for controlling routing of data. It is determined whether at least one data flow is active, the at least one data flow having an ingress portion of a current ingress path to a first point from a second point and an egress portion of a current egress path to the second point from the first point. Another data flow is routed via a next ingress portion of a next path to the first point from the second point.

Compact routing schemes

Abstract: We describe several compact routing schemes for general weighted undirected networks. Our schemes are simple and easy to implement. The routing tables stored at the nodes of the network are all very small. The headers attached to the routed messages, including the name of the destination, are extremely short. The routing decision at each node takes constant time. Yet, the stretch of these routing schemes, i.e., the worst ratio between the cost of the path on which a packet is routed and the cost of the cheapest path from source to destination, is a small constant. Our schemes achieve a near-optimal tradeoff between the size of the routing tables used and the resulting stretch. More specifically, we obtain: A routing scheme that uses only O (n 1/2) bits of memory at each node of an n-node network that has stretch 3. The space is optimal, up to logarithmic factors, in the sense that every routing scheme with stretch n2), and every routing scheme with stretch n3/2). The headers used are only (1 + O(1)) log2> n-bits long and each routing decision takes constant time. A variant of this scheme with [log2 n] -bit headers makes routing decisions in O(log log n) time. Also, for every integer k > 2, a general handshaking based routing scheme that uses O (n1/k) bits of memory at each node that has stretch 2k - 1. A conjecture of Erdos from 1963, settled for k = 3, 5, implies that the routing tables are of near-optimal size relative to the stretch. The handshaking is similar in spirit to a DNS lookup in TCP/IP. Headers are O(log2 n) bits long and each routing decision takes constant time. Without handshaking, the stretch of the scheme increases to 4k - 5. One ingredient used to obtain the routing schemes mentioned above, may be of independent practical and theoretical interest: A shortest path routing scheme for trees of arbitrary degree and diameter that assigns each vertex of an n-node tree a (1 + O(1)) log2 n-bit label. Given the label of a source node and the label of a destination it is possible to compute, in constant time, the port number of the edge from the source that heads in the direction of the destination. The general scheme for k > 2 also uses a clustering technique introduced recently by the authors. The clusters obtained using this technique induce a sparse and low stretch tree cover of the network. This essentially reduces routing in general networks into routing problems in trees that could be solved using the above technique.

Online power-aware routing in wireless Ad-hoc networks

Abstract: This paper discusses online power-aware routing in large wireless ad-hoc networks for applications where the message sequence is not known. We seek to optimize the lifetime of the network. We show that online power-aware routing does not have a constant competitive ratio to the off-line optimal algorithm. We develop an approximation algorithm called max-min zPmin that has a good empirical competitive ratio. To ensure scalability, we introduce a second online algorithm for power-aware routing. This hierarchical algorithm is called zone-based routing. Our experiments show that its performance is quite good.

Performance of multipath routing for on-demand protocols in mobile ad hoc networks

Abstract: Mobile ad hoc networks are characterized by multi-hop wireless links, absence of any cellular infrastructure, and frequent host mobility. Design of efficient routing protocols in such networks is a challenging issue. As class of routing protocols called on-demandprotocols hs recently found attention because of their low routing overhead. The on-demand protocols depend on query floods to discover routes whenever a new route is needed. Such floods take up a substantial portion of network bandwidth. We focus on a particular on-demand protocol, called Dynamic Source Routing, and show how intelligent use of multipath techniques can reduce the frequency of query floods. We develop an analytic modeling framework to determine the relative frequency of query floods for various techniques. Our modeling effort shows that while multipath routing is significantly better than single path routing, the performance advantage is small beyond a few paths and for long paths lengths. It also shows that providing all intermediate nodes in the primary (shortest) route with alternative paths has a significantly better performance than providing only the source with alternate paths. We perform some simulation experiments which validate these findings.

Issues for routing in the optical layer

Abstract: Optical layer control planes based on MPLS and other Internet protocols hold great promise because of their proven scalability, ability to support rapid provisioning, and auto discovery and self-inventory capabilities and are under intense study in various standards bodies. To date however little attention has been paid to aspects of the optical layer which differ from those found in data networking. We study three such aspects which impact routing: network elements which are reconfigurable, but in constrained ways; transmission impairments which may make some routes unusable; and diversity. We conclude that if emerging optical technology is to be maximally exploited, heterogeneous technologies with dissimilar routing constraints are likely. Four alternative architectures for dealing with this eventuality are identified and some trade-offs between centralizing or distributing some aspects of routing are discussed.

Minimum-energy broadcast routing in static ad hoc wireless networks

Abstract: Energy conservation is a critical issue in ad hoc wireless networks for node and network life, as the nodes are powered by batteries only. One major approach for energy conservation is to route a communication session along the routes which requires the lowest total energy consumption. This optimization problem is referred to as minimum-energy routing. While minimum-energy unicast routing can be solved in polynomial time by shortest-path algorithms, it remains open whether minimum-energy broadcast routing can be solved in polynomial time, despite the NP-hardness of its general graph version. Previously three greedy heuristics were proposed in Wieselthier et al. (2000): MST (minimum spanning tree), SPT (shortest-path tree), and BIP (broadcasting incremental power). They have been evaluated through simulations in Wieselthier et al.], but little is known about their analytical performance. The main contribution of this paper is the quantitative characterization of their performances in terms of approximation ratios. By exploring geometric structures of Euclidean MSTs, we have been able to prove that the approximation ratio of MST is between 6 and 12, and the approximation ratio of BIP is between /sup 13///sub 3/ and 12. On the other hand, the approximation ratio of SPT is shown to be at least /sup n///sub 2/, where n is the number of receiving nodes. To our best knowledge, these are the first analytical results for minimum-energy broadcasting.

Vehicle routing and reverse logistics: The vehicle routing problem with simultaneous delivery and pick-up

Abstract: Recently, the increasing focus on environmental protection has led to significant changes in logistics processes In addition to the distribution process to the customers, re-usable packaging and goods to be recycled or remanufactured have to be transported in the reverse direction If both tasks have to be performed simultaneously at the customers' locations which are serviced by a fleet of vehicles stationed in a depot or distribution/redistribution center, the vehicle routing problem with simultaneous delivery and pick-up arises In this paper, the relation between this problem and other vehicle routing problems is investigated A heuristic construction procedure is suggested The proposed algorithm is successfully applied to a real-life problem as well as test instances introduced in the literature earlier In addition, randomly generated instances are tackled in order to try to determine favorable settings for the parameters used in the solution approach

Router and methods using network addresses for virtualization

Abstract: A router for use in a network includes a scalable architecture and performs methods for implementing quality of service on a logical unit behind a network port; and for implementing storage virtualization. The architecture includes a managing processor, a supervising processor; and a plurality of routing processors coupled to a fabric. The managing processor has an in-band link to a routing processor. A routing processor receives a frame from the network, determines by parsing the frame, the protocol and logical unit number, and routes the frame to a queue according to a traffic class associated with the logical unit number in routing information prepared for the processors. An arbitration scheme empties the queue in accordance with a deficit round robin technique. If a routing processor detects the frame's destination is a virtual entity, and so is part of a virtual transaction, the router conducts a nonvirtual transaction in concert with the virtual transaction. The nonvirtual transaction accomplishes the intent of the virtual transaction but operates on an actual network port, for example, a storage device.

Dynamic load-aware routing in ad hoc networks

Abstract: Ad hoc networks are deployed in situations where no base station is available and a network has to be built impromptu. Since there is no wired backbone, each host is a router and a packet forwarder. Each node may be mobile, and topology changes frequently and unpredictably. Routing protocol development has received much attention because mobility management and efficient bandwidth and power usage are critical in ad hoc networks. No existing protocol however, considers the load as the main route selection criteria. This routing philosophy can lead to network congestion and create bottlenecks. We present dynamic load-aware routing (DLAR) protocol that considers intermediate node routing loads as the primary route selection metric. The protocol also monitors the congestion status of active routes and reconstructs the path when nodes of the route have their interface queue overloaded. We describe three DLAR algorithms and show their effectiveness by presenting and comparing simulation results with an ad hoc routing protocol that uses the shortest paths.

Geometric spanner for routing in mobile networks

Abstract: We propose a new routing graph, the Restricted Delaunay Graph (RDG), for ad hoc networks. Combined with a node clustering algorithm RDG can be used as an underlying graph for geographic routing protocols. This graph has the following attractive properties: (1) it is a planar graph; (2) between any two nodes there exists a path in the RDG whose length, whether measured in terms of topological or Euclidean distance, is only a constant times the optimum length possible; and (3) the graph can be maintained efficiently in a distributed manner when the nodes move around. Furthermore, each node only needs constant time to make routing decisions. We also show by simulation that the RDG outperforms the previously proposed routing graphs under the Greedy Perimeter Stateless Routing (GPSR) protocol. In addition, we investigate theoretical bounds on the quality of paths discovered using GPSR

Lagrange relaxation based method for the QoS routing problem

Abstract: In this paper a practically efficient QoS routing method is presented, which provides a solution to the delay constrained least cost routing problem. The algorithm uses the concept of aggregated costs and provides an efficient method to find the optimal multiplier based on Lagrange relaxation. This method is proven to be polynomial and it is also efficient in practice. The benefit of this method is that it also gives a lower bound on the theoretical optimal solution along with the result. The difference between the lower bound and the cost of the found path is very small proving the good quality of the result. Moreover, by further relaxing the optimality of paths, an easy way is provided to control the trade-off between the running time of the algorithm and the quality of the found paths. We present a comprehensive numerical evaluation of the algorithm, by comparing it to a wide range of QoS routing algorithms proposed in the literature. It is shown that the performance of the proposed polynomial time algorithm is close to the optimal solution computed by an exponential algorithm.

Methods, apparatuses and systems facilitating deployment, support and configuration of network routing policies

Abstract: Methods, apparatuses and systems relating to the control and application of policies for routing data over a computer network, such as the Internet. Some implementations of the invention facilitate the configuration, deployment and/or maintenance of network routing policies. Some implementations of the invention are particularly useful for controlling the routing of data among autonomous systems or organizations. Certain implementations allow for dynamic modification of routing policy based on such factors as current Internet performance, load sharing, user-defined parameters, and time of day.

Dynamic lightpath establishment in wavelength routed WDM networks

Abstract: In wavelength-routed WDM networks, a control mechanism is required to set up and take down all-optical connections. Upon the arrival of a connection request, this mechanism must be able to select a route, assign a wavelength to the connection, and configure the appropriate optical switches in the network. The mechanism must also be able to provide updates to reflect which wavelengths are currently being used on each link so that nodes may make informed routing decisions. In this work, we review control mechanisms proposed in the literature. We also investigate and compare two different distributed control mechanisms for establishing all-optical connections in a wavelength-routed WDM network: an approach based on link-state routing, and one based on distance-vector routing.

High-performance addressing and routing of data packets with semantically descriptive labels in a computer network

Abstract: A method, system and apparatus for routing data through a network based on the content or semantics of data. Semantic routing engines route the data through the network based upon information maintained in routing tables. The routing tables used to route the content through the network are derived by aggregating information about either content consumers or content producers into ontological trees.

The impact of Internet policy and topology on delayed routing convergence

Abstract: This paper examines the role inter-domain topology and routing policy play in the process of delayed Internet routing convergence. In previous work, we showed that the Internet lacks effective inter-domain path fail-over. Unlike circuit-switched networks which exhibit fail-over on the order of milliseconds, we found Internet backbone routers may take tens of minutes to reach a consistent view of the network topology after a fault. In this paper, we expand an our earlier work by exploring the impact of specific Internet provider policies and topologies on the speed of routing convergence. Based on data from the experimental injection and measurement of several hundred thousand inter-domain routing faults, we show that the time for end-to-end Internet convergence depends on the length of the longest possible backup autonomous system path between a source and destination node. We also demonstrate significant variation in the convergence behavior of Internet service providers, with the larger providers exhibiting the fastest convergence latencies. Finally, we discuss possible modifications to BGP and provider routing policies which if deployed, would improve inter-domain routing convergence.

MP-DSR: a QoS-aware multi-path dynamic source routing protocol for wireless ad-hoc networks

Abstract: Routing in wireless ad-hoc networks has received significant attention in the literature due to the fact that the dynamic behavior of these networks poses many technical challenges on the design of an effective routing scheme. Though on-demand routing approaches have been shown to perform well, they generally lack the support for quality-of-service (QoS) with respect to data transmission. In order to select a subset of end-to-end paths to provide increased stability and reliability of routes, a new QoS metric, end-to-end reliability, is defined and emphasized. We present a distributed multi-path dynamic source routing protocol (MP-DSR)for wireless ad-hoc networks to improve QoS support with respect to end-to-end reliability. Our protocol forwards outgoing packets along multiple paths that are subject to a particular end-to-end reliability requirement. A simulation study is performed to demonstrate the effectiveness of our proposed protocol, particularly the fact that MP-DSR achieves a higher rate of successful packet delivery than existing best-effort ad-hoc routing protocols, such as the dynamic source routing (DSR).

Multipath routing in the presence of frequent topological changes

Abstract: In this article we propose a framework for multipath routing in mobile ad hoc networks and provide its analytical evaluation. The instability of the topology (e.g., failure of links) in these types of networks, due to nodal mobility and changes in wireless propagation conditions, makes transmission of time-sensitive information a challenging problem. To combat this inherent unreliability of these networks, we propose a routing scheme that uses multiple paths simultaneously by splitting the information among the multitude of paths, to increase the probability that the essential portion of the information is received at the destination without incurring excessive delay. Our scheme works by adding some overhead to each packet, which is calculated as a linear function of the original packet bits. The resulting packet (information and overhead) is fragmented into smaller blocks and distributed over the available paths. Our goal is, given the failure probabilities of the paths, to find the optimal way to fragment and then distribute the blocks to the paths so that the probability of reconstructing the original information at the destination is maximized. Our algorithm has low time complexity, which is crucial since the path failure characteristics vary with time and the optimal block distribution has to be recalculated in real time.

Internet traffic engineering without full mesh overlaying

Abstract: The overlay approach has been widely used by many service providers for traffic engineering in large Internet backbones. In the overlay approach, logical connections are set up between edge nodes to form a full mesh virtual network on top of the physical topology. IP routing is then run over the virtual network. Traffic engineering objectives are achieved through carefully routing logical connections over the physical links. Although the overlay approach has been implemented in many operational networks, it has a number of well-known scaling issues. This paper proposes a new approach, which we call the integrated approach, to achieve traffic engineering without full-mesh overlaying. In the integrated approach, IP routing runs natively over the physical topology rather than over the virtual network. Traffic engineering objectives are realized by setting appropriate link metrics in IP routing protocols. We first illustrate our approach with a simple network, then present a formal analysis of the integrated approach and a method for deriving the appropriate link weights. Our analysis shows that for any given set of optimal routes of the overlay approach with respect to a set of traffic demands, the integrated approach can achieve exactly the same result by reproducing them as shortest paths. We further extend the result to a more generic one: for any arbitrary set of routes, as long as they are not loopy, they can be converted to shortest-paths with respect to some set of positive link weights. A theoretical insight of our result is that the optimal routing (with respect to any objective function) is always shortest path routing with respect to some appropriate positive link weights.

Dynamic routing of locally restorable bandwidth guaranteed tunnels using aggregated link usage information

Abstract: We consider a new QoS routing problem which requires the on-line routing of a bandwidth guaranteed path along with the setting up of bypass paths for every link or node traversed by the primary active path. The bypass paths are used for fast local restoration where upon a link or node failure, the first upstream node re-establishes path continuity (with bandwidth guarantees) by switching to the bypass path for the failed node or link, The routing objective is to minimize the bandwidth usage for each connection so as optimize use of network resources while protecting against single node or link failure. Bandwidth efficiency is achieved by exploiting the potential for inter-demand and intra-demand backup bandwidth sharing. We develop a new algorithm for this routing problem which only uses aggregated link usage information (total bandwidth consumed on each link by active paths, total bandwidth consumed on each link by backup paths, and the residual bandwidths) that is easily obtainable by proposed routing protocol extensions. We show that the algorithm performs well in terms of the number of rejected requests and the total bandwidth used, The main use of this algorithm is for MPLS network routing and for wavelength routing in optical networks with wavelength conversion.

Router and routing protocol redundancy

Abstract: A router and routing protocol redundancy are disclosed to reduce service outage or degradation for a network device and thus to increase service availability on a network due to software and hardware failures of the network device. A network device such as router includes a redundancy platform having an active controller system and a standby controller system. A routing protocol state change is received or generated by the active controller system. The received or generated routing protocol state change is replicated to the standby controller system. By replicating the routing protocol state change, the standby controller system can maintain the routing protocol sessions for the network device if a failure occurs in the active controller system. Furthermore, the routing protocol states are maintained in realtime to handle the dynamic changes created by routing protocols.

Enhancing ad hoc routing with dynamic virtual infrastructures

Abstract: Several routing algorithms for mobile ad hoc networks (MANETs) have been proposed previously. With the exception of a few, these protocols (i) involve all nodes in the route management process, (ii) rely on the use of broadcast relays for route computation, and (iii) are primarily reactive in nature. Related work has shown that the capacity utilization in ad hoc networks decreases significantly when broadcast relays or "broadcast storms" are performed frequently. This effect is compounded when all nodes in the network take part in the route computation. We propose and study an approach based on overlaying a virtual infrastructure adaptation of the core, proposed by Sivakumar, Sinha and Bharghavan (see IEEE Journal on Selected Areas in Communications, vol.17, no.8, p.1454-65, 1999) on an ad hoc network and operating routing protocols over the infrastructure. The core enables routing protocols to use only a subset of nodes in the network for route management and avoid the use of broadcast relays. Using the ns-2 simulator we evaluate the performance of two ad hoc routing protocols, dynamic source routing (DSR) and ad hoc on demand distance vector (AODV), when they are operated over the core and compare their performance against those of their basic versions.

The impact of routing policy on Internet paths

Abstract: The impact of routing policy on Internet paths is poorly understood. In theory, the policy can inflate shortest-router-hop paths. To our knowledge, the extent of this inflation has not been previously examined. Using a simplified model of the routing policy in the Internet, we obtain approximate indications of the impact of policy routing on Internet paths. Our findings suggest that the routing policy does impact the length of Internet paths significantly. For instance, in our model of the routing policy, some 20% of Internet paths are inflated by more than five router-level hops.