Showing papers on "Virtual routing and forwarding published in 2015"

Central Control Over Distributed Routing

Abstract: Centralizing routing decisions offers tremendous flexibility, but sacrifices the robustness of distributed protocols. In this paper, we present Fibbing, an architecture that achieves both flexibility and robustness through central control over distributed routing. Fibbing introduces fake nodes and links into an underlying link-state routing protocol, so that routers compute their own forwarding tables based on the augmented topology. Fibbing is expressive, and readily supports flexible load balancing, traffic engineering, and backup routes. Based on high-level forwarding requirements, the Fibbing controller computes a compact augmented topology and injects the fake components through standard routing-protocol messages. Fibbing works with any unmodified routers speaking OSPF. Our experiments also show that it can scale to large networks with many forwarding requirements, introduces minimal overhead, and quickly reacts to network and controller failures.

Optimized network traffic engineering using segment routing

Abstract: Segment Routing is a proposed IETF protocol to improve traffic engineering and online route selection in IP networks. The key idea in segment routing is to break up the routing path into segments in order to enable better network utilization. Segment routing also enables finer control of the routing paths and can be used to route traffic through middle boxes. This paper considers the problem of determining the optimal parameters for segment routing in the offline and online cases. We develop a traffic matrix oblivious algorithm for robust segment routing in the offline case and a competitive algorithm for online segment routing. We also show that both these algorithms work well in practice.

SNAMP: Secure namespace mapping to scale NDN forwarding

Abstract: Named Data Networking (NDN) is a proposed information-centric design for the future Internet architecture, where application names are directly used to route requests for data This key component of the architecture raises concerns about scalability of the forwarding system in NDN network, ie, how to keep the routing table sizes under control given unbounded nature of application data namespaces In this paper we apply a well-known concept of Map-and-Encap to provide a simple and secure namespace mapping solution to the scalability problem More specifically, whenever necessary, application data names can be mapped to a set of globally routable names that are used to retrieve the data By including such sets in data requests, we are informing (more precisely, hinting) the forwarding system of the whereabouts of the requested data, and such hints can be used when routers do not know from where to retrieve the data using application data names alone This solution enables NDN forwarding to scale with the Internet's well-understood routing protocols and operational practice, while keeping all the benefits of the new NDN architecture

Corrections to "Link-state routing with hop-by-hop forwarding can achieve optimal traffic engineering"

Abstract: Presents corrections to the paper, “Link-state routing with hop-by-hop forwarding can achieve optimal traffic engineering,” (Xu, D., et al)IEEE/ACM Trans. Netw., vol. 19, no. 6, pp. 1717–1730, Dec. 2011).

Towards a flexible data center fabric with source routing

Abstract: An emerging architecture for software-defined data centers andWANs is the network fabric, where complex application-sensitive functions are factored out, leaving the network itself to provide a simple, robust high-performance data delivery abstraction. This requires performing route optimization, in real time and across a diverse choice of paths. A large variety of techniques have been proposed to provide path diversity for network fabrics. But, running up against the constraint of forwarding table size, these proposals are topology-dependent, complex, and still only provide limited path choice which (we show) can impact performance.We propose a simple approach to realize the vision of a flexible, high-performance fabric: the network should expose every possible path, allowing a controller or edge device maximum choice. To this end, we observe that source routing can be encoded and processed compactly into a single field, even in large networks, with OpenFlow 1.3. We show that, in addition to the expected decrease in required forwarding table size, source routing supports optimal throughput performance, in some cases significantly higher than some past proposals. We thus believe source routing offers a clean abstraction and efficient implementation for future network fabrics.

Poptrie: A Compressed Trie with Population Count for Fast and Scalable Software IP Routing Table Lookup

Abstract: Internet of Things leads to routing table explosion. An inexpensive approach for IP routing table lookup is required against ever growing size of the Internet. We contribute by a fast and scalable software routing lookup algorithm based on a multiway trie, called Poptrie. Named after our approach to traversing the tree, it leverages the population count instruction on bit-vector indices for the descendant nodes to compress the data structure within the CPU cache. Poptrie outperforms the state-of-the-art technologies, Tree BitMap, DXR and SAIL, in all of the evaluations using random and real destination queries on 35 routing tables, including the real global tier-1 ISP's full-route routing table. Poptrie peaks between 174 and over 240 Million lookups per second (Mlps) with a single core and tables with 500--800k routes, consistently 4--578% faster than all competing algorithms in all the tests we ran. We provide the comprehensive performance evaluation, remarkably with the CPU cycle analysis. This paper shows the suitability of Poptrie in the future Internet including IPv6, where a larger route table is expected with longer prefixes.

BEEINFO: Interest-Based Forwarding Using Artificial Bee Colony for Socially Aware Networking

Abstract: Socially aware networking (SAN) provides a promising paradigm for routing and forwarding data packets by exploiting social properties of involved entities, for example, in vehicular social networks (VSNs). The mobility of individuals often features some regularity in location and time, particularly in vehicular environments. However, individuals' learning capability and awareness to the dynamic environments have not been well explored in the literature. Inspired by the artificial bee colony, we present BEEINFO, which is a set of interest-based forwarding schemes for SAN, which consists of BEEINFO-D, BEEINFO-S, and BEEINFO-D&S. BEEINFO adopts the food foraging behavior of bees to detect the environment information and to optimize the forwarding procedure. BEEINFO takes advantage of individuals' perceiving and learning capability to gather information of density and social ties. BEEINFO-D, BEEINFO-S, and BEEINFO-D&S are distinct from each other according to different utilization of density and social ties. This enhances the adaptability to dynamic environments. Additionally, BEEINFO performs message scheduling and buffer management to improve the forwarding performance. Extensive simulations have been conducted to compare BEEINFO with two representative protocols, i.e., PRoPHET and Epidemic. The results illustrate that BEEINFO outperforms PRoPHET and Epidemic with higher message delivery ratio, less overhead, and fewer hop counts.

Scalable handling of bgp route information in vxlan with evpn control plane

Abstract: A method for programming a MAC address table by a first leaf node in a network comprising a plurality of leaf nodes is provided. Each leaf node comprises one or more Virtual Tunnel End Points (“VTEPs”) and instantiates a plurality of Virtual Routing and Forwarding elements (“VRFs”), with a corresponding Bridge Domain (“BD”) assigned to each VRF. The method includes obtaining information indicating one or more VTEP Affinity Groups (VAGs), each VAG comprising an identification of one VTEP per leaf node, obtaining information indicating assignment of each VRF to one of the VAGs, assigning each VAG to a unique Filtering Identifier (“FID”), thereby generating one or more FIDs, and programming the MAC address table, using FIDs instead of BDs, by populating the MAC address table with a plurality of entries, each entry comprising a unique combination of a FID and a MAC address of a leaf node.

A fault-tolerant forwarding strategy for interest-based information centric networks

Abstract: We show that the forwarding strategies in the named data networking (NDN) architecture and the original content centric networking (CCN) architecture cannot ensure that Interests return the requested data objects when routing-table loops exist in a stable or dynamic network. We also show that no correct Interest forwarding strategy that allows Interest aggregation can be designed solely on the basis of identifying Interests uniquely in order to detect Interest loops. We introduce SIFAH (Strategy for Interest Forwarding and Aggregation with Hop-Counts). SIFAH prevents or detects Interest loops when Interests are aggregated or forwarded over one or multiple paths. As a result, it is far more efficient than the forwarding strategy in NDN and the original CCN proposal. SIFAH operates by having forwarding information bases (FIB) store the next hops and number of hops to named content prefixes, and by using Interests that state the names of requested content and hop counts that reflect the information in their FIBs.

A Joint Multi-Layer Planning Algorithm for IP Over Flexible Optical Networks

Abstract: We consider the multi-layer network planning problem for IP over flexible optical networks, which consists of three subproblems at two layers: the Routing problem at the IP-layer (IPR), the routing, modulation level (RML), and the spectrum allocation (SA) problems at the optical layer. The input includes the IP end-to-end traffic matrix, the modular model of the IP/MPLS routers, and the feasible transmission configurations of the flexible optical transponders. Demands are served for their requested rates by selecting the IP/MPLS routers modules to be used, the routes in the IP (virtual) topology, and the corresponding paths and spectrum slots in the underlying optical topology, together with the optical transponders' configurations. The proposed algorithm follows a multi-cost approach that solves jointly the IPR, the RML, and the SA problems. It serves demands one-by-one, reusing existing equipment and favoring the deployment of new equipment that could also be reused by subsequent connections, aiming to minimize the total network cost. The problem definition is generic and the proposed algorithm is applicable to both fixed- and flex-grid optical networks. We evaluate the performance gains that can be obtained by the proposed joint multi-layer network planning solution, as opposed to a sequential planning solution that separately plans the IP and optical layers. We also compare a flexible network, using flex-grid optical switches and flexible optical transponders, to a mixed line rate (MLR) network, using fixed-grid or flex-grid optical switches but fixed optical transponders.

An entropy-based probabilistic forwarding strategy in Named Data Networking

Abstract: The forwarding strategy is the key to the resiliency and efficiency of Named Data Networking (NDN), which is a new and fundamental research area. For forwarding strategy, dynamically selecting an optimal interface from multiple alternative interfaces to forward an Interest packet is indeed a multiple attribute decision making (MADM) problem. In this paper, an entropy-based probabilistic forwarding (EPF) strategy is proposed to make a stochastic interface selection based on the combination of interfaces' dynamic availabilities and static routing information, which achieves better load balance in comparison with deterministic interface selection. By objectively assigning weights to attributes and considering multiple real-time network condition metrics, EPF can obtain the availabilities of interfaces more accurately and comprehensively. Since additional network metrics can be easily added and integrated into interfaces' assessment model, EPF provides good extensibility. In addition, we innovatively define two parameters (γ, δ) which can be used to trade off the effect factors between static routing information and dynamic running status of interfaces to customize EPF strategy for different network and application scenarios. Experiments show that EPF can realize preferable load balance and achieve higher throughput compared to the representative BestRoute forwarding strategy.

CAMF: Context-Aware Message Forwarding in Mobile Social Networks

Abstract: In mobile social networks (MSN), with the aim of conserving limited resources, egotistic nodes might refuse to forward messages for other nodes. Different from previous work which mainly focuses on promoting cooperation between selfish nodes, we consider it from a more pragmatic perspective in this paper. Be specific, we regard selfishness as a native attribute of a system and allow nodes to exhibit selfish behavior in the process of message forwarding. Apparently, selfishness has a profound influence on routing efficiency, and thus novel mechanisms are necessary to improve routing performance when self-centered nodes are considered. We first put forward a stateless approach to measure encounter opportunities between nodes, and represent forwarding capabilities of nodes by combining the acquired encounter opportunities with node selfishness. We then quantify receiving capabilities of nodes based on their available buffer size and energy. Taking both forwarding and receiving capabilities into account, we finally present a forwarding set mechanism, which could be deduced to a multiple knapsack problem to maximize the forwarding profit. Consequently, we take all the above studies into the design of a context-aware message forwarding algorithm (CAMF). Extensive trace-driven simulations show that CAMF outperforms other existing algorithms greatly. In fact, it achieves a surprisingly high routing performance while consumes low transmission cost and resource in MSN.

Load balancing in IP networks using generalized destination-based multipath routing

Abstract: Intradomain traffic engineering (TE) has become an indispensable tool for Internet service providers (ISPs) to optimize network performance and utilize network resources efficiently. Various explicit routing TE methods were recently proposed and have been able to achieve high network performance. However, explicit routing has high complexity and requires large ternary content addressable memories (TCAMs) in the routers. Moreover, it is costly to deploy explicit routing in IP networks. In this paper, we present an approach, called generalized destination-based multipath routing (GDMR), to achieve the same high performance as explicit routing. The main contribution of this paper is that we prove that an arbitrary explicit routing can be converted to a loop-free destination-based routing without any performance penalty for a given traffic matrix. We present a systematic approach including a heuristic algorithm to realize GDMR. Extensive evaluation demonstrates the effectiveness and robustness of GDMR.

A Virtual Coordinate-Based Bypassing Void Routing for Wireless Sensor Networks

Abstract: To solve the routing void problem in geographic routing, high control overhead and transmission delay are usually taken in wireless sensor networks. Inspired by the structure composed of edge nodes around which there is no routing void, an efficient bypassing void routing protocol based on virtual coordinates is proposed in this paper. The basic idea of the protocol is to transform a random structure composed of void edges into a regular one by mapping edge nodes coordinates to a virtual circle. By utilizing the virtual circle, the greedy forwarding can be prevented from failing, so that there is no routing void in forwarding process from source to destination and control overhead can be reduced. Furthermore, the virtual circle is beneficial to reduce average length of routing paths and decrease transmission delay. Simulations show the proposed protocol has higher delivery ratio, shorter path length, less control packet overhead, and energy consumption.

Hybrid information forwarding in VANETs through named data networking

Abstract: This paper investigates the issue of multi-hop forwarding in Vehicular Ad hoc Networks (VANETs), which is suffering from rapidly changing topology, short-lived and intermittent connectivity. Designed to replace TCP/IP using named data, Named Data Networking (NDN) has natural advantages to greatly overcome those challenges because of its multi-source and in-network caching characteristics. However, in the wireless environment the Interest and Data, proposed in NDN, are usually flooded because of the absence of Forwarding Information Base (FIB). To tackle this problem, we propose HVNDN, a hybrid forwarding strategy through NDN. More specifically, HVNDN introduces opportunistic and probabilistic forwarding strategy for location-dependent and location-independent information, respectively, which takes full advantage of geographic information and the characteristics of named data in VANETs. To make Vehicle-to-Vehicle (V2V) communication more effective and reliable, we design elaborate Interest and Data packets formats, retransmission and acknowledgement mechanism in HVNDN. Simulation results from NS-3 demonstrate that the proposed forwarding strategy outperforms the state-of-art scheme with less end-to-end delay and overhead.

Forwarding Schemes for EM-based Wireless Nanosensor Networks in the Terahertz Band

Abstract: Electromagnetic-based Wireless NanoSensor Networks (EM-WNSNs) operating in the TeraHertz (THz) band (0.1 THz--10 THz) has been in focus recently because of potential applications in nano-scale scenarios. However, one major hurdle for advancing nano-scale communications is the lack of suitable networking protocols to address current and future needs of nanonetworks. Working together with routing that finds the path from a source to destination, forwarding is a networking task of sending a packet to the next-hop along its path to the destination. While forwarding has been straightforward in traditional wired networks, forwarding schemes now play a vital role in determining wireless network performance. In this paper, we propose a channel-aware forwarding scheme and compare it against traditional forwarding schemes for wireless sensor networks. To fit the peculiarity of EM-WNSNs, the channel-aware forwarding scheme makes forwarding decision considering the frequency selective pecularities of the THz channel which are undesirable from a networking perspective. It is shown through simulation that the proposed channel-aware forwarding scheme outperforms traditional forwarding schemes in terms of the end-to-end capacity while maintaining comparable performance for delay.

Enabling Correct Interest Forwarding and Retransmissions in a Content Centric Network

Abstract: We show that the mechanisms used in the name data networking (NDN) and the original content centric networking (CCN) architectures may not detect Interest loops, even if the network in which they operate is static and no faults occur. Furthermore, we show that no correct Interest forwarding strategy can be defined that allows Interest aggregation and attempts to detect Interest looping by identifying Interests uniquely. We introduce SIFAH (Strategy for Interest Forwarding and Aggregation with Hop-Counts), the first Interest forwarding strategy shown to be correct under any operational conditions of a content centric network. SIFAH operates by having forwarding information bases (FIBs) store the next hops and number of hops to named content, and by having each Interest state the name of the requested content and the hop count from the router forwarding an Interest to the content. We present the results of simulation experiments using the ndnSIM simulator comparing CCN and NDN with SIFAH. The results of these experiments illustrate the negative impact of undetected Interest looping when Interests are aggregated in CCN and NDN, and the performance advantages of using SIFAH.

On Exploring Data Forwarding Problem in Opportunistic Underwater Sensor Network Using Mobility-Irregular Vehicles

Abstract: Data forwarding techniques in opportunistic underwater sensor networks (OUSNs) are significantly different from those of wireless sensor networks or delay-tolerant networks, due to the irregular mobility of nodes. To this end, an Opportunistic Forwarding Algorithm based on Irregular Mobility (OFAIM) is proposed hereby, which intermittently computes and chooses the appropriate paths of an end-to-end data session. In OFAIM, the contacting probabilities among nodes are estimated according to current nodes statuses. OFAIM is particularly suitable for heterogeneous networks composed of nodes with different communication and movement ranges. The performance of OFAIM is also analyzed through simulations, which indicate that OFAIM achieves a satisfactory delivery ratio (larger than 67% at the worst case) within a limited duration, while the message cost is largely reduced (the number of forwarding copies at every slot is restricted to two or three) compared with epidemic forwarding, motion vector forwarding, and predict and spread forwarding.

Exploiting Small World Properties for Message Forwarding in Delay Tolerant Networks

Abstract: In Delay Tolerant Networks (DTNs), the connections between mobile nodes are always disrupted and constant end-to-end paths rarely exist. In order to cope with these communication challenges, most existing DTN routing algorithms favour the “multi-hop forwarding” fashion where a message can be forwarded by multiple relay nodes in the hope that one of the employed relay nodes can deliver the message to the destination node. Since aggressively employing relay nodes may incur the intolerable delivery cost in DTNs, it is meaningful to design a cost-efficient routing algorithm that can achieve a high delivery performance. In this paper, we first design a novel delivery metric to measure the forwarding capability of nodes. Then, we utilize small-world properties to design the principles of relay node selection, e.g., limiting the number of relays and finding the appropriate relay nodes, and further develop a cost-efficient social-aware forwarding algorithm called TBSF. Extensive simulations on real mobility traces are conducted to evaluate the performance of TBSF, and the results demonstrate its efficiency and usefulness.

Control device discovery in networks having separate control and forwarding devices

Abstract: A Software Defined Network (SDN) includes a plurality of forwarding devices and a routing control device located separate from the forwarding devices. The routing control device, establishes paths to and from the network forwarding devices. Using such paths, forwarding devices send the routing control device information reflecting the topology if the network. Embodiments disclosed herein enable automatic discovery of the topology of the network and the paths to and from the routing control device.

A Novel Hybrid Routing Forwarding Algorithm in SDN Enabled Wireless Mesh Networks

Abstract: As an essential part of next generation Internet, Wireless Mesh Networks (WMNs) have attracted much research attention due to its potential advantages including low up-front cost, ease of deployment, enhanced capacity and service coverage. However, the inherit features of wireless multi-hop networks have put forward a severe challenge for traffic engineering problem. Conventional traffic engineering techniques either locally manipulate network traffic or adopt unreliable best-effort delivery mechanism. Software Defined Networking (SDN) is a new networking paradigm that separates the network control plane from the packet forwarding plane and provides applications with an abstracted centralized view of the distributed network state. A logically centralized controller that has a global network view is responsible for all the control decisions and it communicates with the network-wide distributed forwarding elements via standardized interfaces. Considering the current price of SDN equipments and deployment cost, this paper proposes an idea that gradually increases the number of SDN forwarding element in the networks. In other words, partly deployment of the SDN forwarding element in the networks can achieve fast forwarding traffic. On this basis, a new traffic engineering algorithms named Hybrid Routing Forwarding Algorithm (HRFA) which is based on SDN forwarding and OSPF (Open Shortest Path First) protocol is designed. This hybrid routing scheme divides the network nodes into conventional nodes and SDN forwarding elements (SDN-FE), and chooses effective forwarding strategies for different network elements, which will improve the overall performance of the networks. In order to verify the performance of the proposed algorithms, a number of simulation experiments are carried out in the NS-2 simulation platform. The results show that compared with the traditional routing forwarding method, HRFA can well increase the normalized throughput, and reduce the delay and packet loss.

Maintaining IP tables

Abstract: Data including a set of one or more resources and one or more associated IP addresses is updated based on monitored DNS responses. A request is received from a client device for a resource identified by an IP address. The IP address is matched to one of the IP addresses in the set of one or more IP addresses. A particular resource associated with the matched IP address is identified. A particular network policy that applies is identified. The identified particular network policy is applied to the received request.

Managing dynamic ip address assignments

Abstract: Various systems and processes may be used to manage Internet Protocol (IP) addresses that are dynamically assigned. In particular implementations, systems and processes for managing IP addresses that are dynamically assigned may include the ability to determine whether an identifier for a web service has been received from a customer having one or more virtual machines in a service provider network, the web service being accessible by the customer's virtual machines over an external communication network. The systems and processes may also include the ability to determine a number of IP addresses for the web service, identify virtual machines of the customer that are allowed to communicate with the web service, generate one or more IP address lists for the identified virtual machines, and update security tables for the identified virtual machines with the IP address lists at server computers hosting the identified virtual machines.

An Efficient Bypassing Void Routing Protocol Based on Virtual Coordinate for WSNs

Abstract: Inspired by the structure composed of edge nodes without routing voids, a routing protocol based on virtual coordinates is proposed in this letter. The basic idea of the proposed protocol is to transform a random structure composed of edge nodes into a regular one by mapping edge nodes to virtual nodes on a virtual circle. The virtual circle can prevent greedy forwarding from failing by proposed strategies, so that control overhead and the average length of routing paths can be reduced. Simulations show the proposed protocol has higher delivery ratio, shorter path length, and less control packet overhead and energy consumption.

Full protection made easy: the DisPath IP fast reroute scheme

Abstract: A major concern in IP networks is to ensure that any topology changes, whether planned or unplanned, do not disrupt network performance. IP Fast Reroute (IP FRR) is a general approach to address this issue by promptly forwarding an IP packet to a predetermined alternate next-hop as soon as the primary next-hop to the destination becomes unavailable. Among the numerous IP FRR schemes proposed to date, the simplest ones do not guarantee protection against every component failure, while more sophisticated ones tend to be difficult to implement due to various inherent complexities, such as nontrivial modifications of IP packets or high resource requirements. This paper presents a simple and efficient IP FRR scheme called DisPath, which leverages several fundamental properties of minimum-cost node-disjoint paths for determining the alternate next-hop toward a given destination. We show that DisPath ensures full coverage, meaning protection against all single link or node failures, with low computational overhead and without the practical complications encountered by other schemes that offer the same level of protection. Our simulations on several realistic instances reveal that DisPath usually creates shorter (and, at worst, not much longer) alternative paths than existing solutions adopted by the industry. Combined with the aforementioned protection guarantee and simplicity of implementation, these results provide strong evidence that DisPath is a most compelling choice of IP FRR scheme.

Rethinking virtual private networks in the software-defined era

Abstract: Multi Protocol Label Switching (MPLS) Virtual Private Networks (VPNs) have seen an unparalleled increasing adoption in the last decade. Although their flexibility as transport technology and their effectiveness for traffic engineering are well recognized, VPNs are difficult to set up and manage, due to the complexity of configurations, to the number of involved protocols, and to the limited control and predictability of network behaviors. On the other hand, Software-Defined Networking (SDN) is a consolidated, yet still emerging paradigm by which the control plane logic of a network device is implemented by an arbitrarily programmed software that runs outside the device itself. We conjugate the effectiveness of traditional VPNs with the programmability of SDN, proposing a novel and improved realization of MPLS VPNs based on SDN. With our approach, provisioning and setup of VPNs are accomplished by using a simple and flexible configuration language. Management and troubleshooting are facilitated because only a minimal set of technologies (notably, just MPLS) is retained. Control and predictability of network behaviors are enhanced by the centralized coordination enforced by the SDN controller. Besides illustrating our proposed approach and specifying the configuration language, we describe a prototype implementation of a controller and the outcome of tests we conducted in several configuration scenarios.

Geographical forwarding methods in vehicular ad hoc networks

Abstract: Vehicular ad hoc networks are new and emerging technology and special class of mobile ad hoc networks that provide wireless communication between vehicles without any fixed infrastructure. Geographical routing has appeared as one of the most scalable and competent routing schemes for vehicular networks. A number of strategies have been proposed for forwarding the packets in geographical direction of the destination, where information of direct neighbors is gained through navigational services. Due to dynamically changing topologies and high mobility neighbor information become outdated. To address these common issues in network different types of forwarding strategies have been proposed. In this review paper, we concentrate on beaconless forwarding methods and their forwarding methods in detail.

Prefix-aware weighted cost multi-path group reduction

Abstract: Methods and systems for generating a forwarding table for a packet switch. The system includes a route manager for the packet switch, configured to identify a plurality of multi-path groups each corresponding to a respective initial set of routing entries in the forwarding table and generate, for one or more multi-path groups, at least one replacement set of routing entries with fewer routing entries than the initial set corresponding to the respective multi-path group. The route manager selects, based on a traffic reduction cost metric, one or more of the replacement sets of routing entries, each corresponding to a different respective multi-path group, and updates the forwarding table with the selected replacement sets. In some implementations, the traffic reduction cost metric includes a traffic characteristic. In some implementations, the packet switch participates in a software-defined network (SDN) and the route manager is part of an SDN controller.