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Evaluation of Fairness in ICN. X. De Foy, JC. Zuniga, B. Balazinski InterDigital (first.last@interdigital.com). Motivation.
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Evaluation of Fairness in ICN X. De Foy, JC. Zuniga, B. Balazinski InterDigital (first.last@interdigital.com)
Motivation As part of the ongoing discussion on the Evaluation Methodology draft, should we measure how “fair” is the usage of network resources in ICN? Is this a real issue? If so, what should we measure?
Potential Fairness Issues in ICN • Since ICNs share resources… • Network resources: bandwidth, in-network storage, NRS, Topology Managers, etc. • Individual nodes resources: CPU, RAM, NIC, Storage, etc. • … a network entity can trick the system to get a larger amount of resources • Receivers, publishers, even routers • … an ICN system design may have a bias • E.g. a too large a bias towards popular content may starve unpopular content objects
Fairness Measures in ICN • Fairness between end users • Throughputs between several competing flows on bottleneck links are compared for interest shaping evaluation in [4] • Fairness between classes of content (e.g. popular vs. unpopular) • Number of replicas depending on popularity in [2] • In these scenarios it is assumed that all users will get similar service for a same class of content: • Response time depending on popularity in [1] • Ratio of throughput gain with/without cache depending on popularity in [3] • … any other examples?
Fairness in a Generic Context • Strategies/Criteria: between fairness and efficiency • Basic strategy is max-min fairness – the goal is to maximize the minimum allocation among all agents • Proportional fairness – compromise between efficiency and a minimal level of fairness between users • Other efficiency-fairness tradeoffs (e.g. α-fairness used in [9] ranging from utilitarian α=0, proportional α=1, max-min α→∞) • Examples of Qualities used to Evaluate Fairness • Share Guarantee: every arriving agent gets at least an equal split of the resources if it wants it • Strategy Proof-ness: no agent may misreport its demand and be better off regardless of demands from other agents • Envy Freeness: an agent would never prefer the allocation of another agent • Pareto Efficiency: changing allocation to make one agent better off would result in making another agent worse
Fairness in Relevant Domains • Sharing of resources in data centers between tenants • Run jobs with resource usage vector (CPU, Memory, etc.), measure number of jobs per tenant • Example: Dominant Resource Fairness [5] • Middle box resource allocation • Multiple resources within a single node, more dynamic allocation (queue scheduling) [6] • Sharing of Resources in P2P Systems • Some peers can use strategies to optimize their gain and minimize their own resource usage [7] • Scheduling in Wireless Ad Hoc networks • Single resource (bandwidth/time slots) allocated at each node in a distributed manner [8]
Evaluation of Fairness in ICN 1/2 • ICN should be fair to end users/receivers. Should it be fair to other entities like publishers and individual content objects as well? • Some resources may be “traded” for others, especially Bandwidth vs. Storage • Multiple content sources/replicas can lead to a distribution of bottlenecks (e.g. network links, routers storage, routers CPU, etc.)
Evaluation of Fairness in ICN 2/2 • Is there an acceptable set of reference setups… • nr receivers, np publishers, no content objects • A network topology with caches/routers/links and placement of receivers/publishers • Some of the topologies used in evaluations are bus, ring, caching tree, topologies with a single congested link, mesh with certain probability of inter-connections. • A usage pattern • … and associated fairness criteria? • General criteria, qualities • Specific agents (receivers, etc.)
Questions to the RG • Is there a common, agreeable definition of fairness for ICN? • Is there a content-oriented aspect of fairness? • Do ICN particularities actually make a difference on how to evaluate fairness (multiple sources, caching vs. bandwidth equivalence)? • Should we include a section on this aspect in the Evaluation Methodology draft?
References [1] Carofiglio et al. “Bandwidth and Storage Sharing Performance in Information Centric Networking”, 2010, Link [2] Tortelli et al. “A Fairness Analysis of Content Centric Networks”, 2012, Link [3] Saucez et al. “Congestion control and in-network caching” (ICNRG IETF84 presentation), 2012, Link [4] Wang et al. “An Improved Hop-by-hop Interest Shaper for Congestion Control in Named Data Networking”, 2013, Link [5] Ghodsi et al. “Dominant Resource Fairness: Fair Allocation of Heterogeneous Resources in Datacenters”, 2010, Link [6] Ghodsi et al. “Multi-resource fair queueing for packet processing”, 2012, Link [7] Piatek et al. “Do incentives build robustness in BitTorrent?”, 2007, Link [8] Tassiulas & Sarkar“Maxmin Fair Scheduling in Wireless Ad Hoc Networks”, 2005, Link [10] Bertsimas et al., “A Characterization of the Efficiency-Fairness Tradeoff”, 2010, Link