On Content Indexing for Off-Path Caching in Information-Centric - PowerPoint PPT Presentation

On Content Indexing for Off-Path Caching in Information-Centric Networks Suzan Bayhan, Liang Wang, Jörg Ott, Jussi Kangasharju, Arjuna Sathiaseelan, Jon Crowcroft University of Helsinki (Finland), TU Munich (Germany), University of Cambridge (UK) ACM ICN, Kyoto, Japan, September 26-28, 2016 1

Where is the ( nearest copy of the ) requested content? Request for content 2

Name resolution service in ICN • Standalone service (look-up by name) o Directory service, Name Resolution Server (NRS) o NRS maps names to locators and routing is done using locators 🙃 Nearest-copy routing ☹ Scalability (temporary copies, update, storage, lookup) • Name-based routing o Route on names 🙃 No need for a particular infrastructure support ☹ Nearest-copy routing? 3

Our contribution • Can we have an NRS that indexes only some of the content but brings most of the benefits? • Partial NRS to balance the tradeoff between scalability and nearest copy routing • We model the content delivery with and without NRS, and formulate an optimization problem to identify which items to index • Our optimal NRS setting aims to minimize the content delivery cost under a limit on maximum number of items to be indexed 4

NRS-based operation in ICN NRS state update, if cache population changes 4 4 NRS request Nearest 2 3 copy location 4 Retrieve content from Content Edge router 1 the nearest provider provider (CP) Request for content 5

Operation without an NRS in ICN CP- 2 CP- 2 2 2 2 3 CP- 1 CP- 1 2 2 3 2 3 1 1 Is there a content Request for Request for copy in my content content neighborhood? • Content retrieval: Redundant • Content discovery: transmissions due to multiple content • Search for content in the neighborhood providers in the search scope • Flooding-based search • Time waste if content is NOT in the nw. 6

Operation without an NRS in ICN Unable to discover this CP CP- 1 External ASes AS Inter-domain Origin server routing of the content for external content Request for content Increase in inter-domain traffic for external content: monetary inefficiency 7

Operation without an NRS in ICN CP- 1 External ASes AS Inter-domain Origin server routing of the content for external content Request for content • Data access latency • Bandwidth inefficiency • Monetary inefficiency 8

A closer look from an AS’ viewpoint • Local content: origin server in External networks Local NRS content info the AS, inter-domain AS routing update resolve AS • External content : origin server NRS name AS outside AS AS AS • To improve scalability: • NRS indexes only some inter-domain monetary cost routing intra-domain fraction(w) of all content bandwidth cost AS routing NRS update catalogue (K) bandwidth cost user requests • Routers update the NRS not upon every single change in their cache , but based on calculated rates under certain false positive and negative probabilities according to rate-distortion theory proposed in Azimdoost et al. B. Azimdoost, C. Westphal, and H. R. Sadjadpour. The price of updating the control plane in ICNs. CoRR , abs/1406.1284, 2014. 9

Which items to index by NRS? • Calculate the cost of content delivery with NRS and without NRS • Indexing gain is the difference between the cost • Index the ones with the highest indexing gain 10

Cost of content delivery: discovery and retrieval Does NRS index content c? No Yes Index-based search (IBS) Flooding-based search (FBS) Check the NRS state Search for content, scoped flooding* Is the content is in the network? Is the content discovered? Yes Yes No Route the request to the nearest CP No Content retrieval Is this a False Alarm? Get the content from No Yes the Origin Server Get the content from the Content retrieval Origin Server Assumption: origin server is known Update NRS state of each on-path cache 11 based on content’s NRS update rate * L. Wang et al. Pro-diluvian: Understanding scoped-flooding 
 for content discovery in ICN. In ACM ICN, 2015.

NRS-based content delivery: more formally System state: <Content state, NRS state> Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered • Above steps are taken if the content is NOT in the edge cache • Content is expected to be in the cache with probability 𝞫 : Che’s approximation 12

NRS-based content delivery: more formally Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered False negative False positive 13

NRS-based content delivery: more formally Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered Rely on IBS 14

NRS-based content delivery: more formally Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered Rely on FBS 15

NRS-based content delivery: more formally Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered Cost of IBS, FBS, and fetching from the origin server : # of transmissions of the message x the message size x cost of transmission/bit • IBS: expected hop distance between the nearest content provider and a randomly selected requesting node • FBS: # of nodes receiving the message for a certain search scope (2 or 3 hops) • Origin server: • expected hop distance between a randomly-selected router and a content provider • inter-AS routing cost 16

NRS-based content delivery: more formally Flooding-based search. NRS state, S NRS ( k ) NRS indexes c k NRS does not index c k Content is retrieved from 0 1 NA 0 Fetch from the origin IBS, fetch from the origin FBS, fetch from the origin AS, if local content Content state k )( 1 − ε 1 ) k ) ε 1 p 00 =( 1 − α k )( 1 − P p 01 =( 1 − α k )( 1 − P p 0 na =( 1 − α k )( 1 − P k ) External AS, if external S ( k ) content 1 Fetch from the origin IBS FBS, fetch from the origin AS, if discovered or local k ( 1 − ε 0 ) k ε 0 p 10 =( 1 − α k ) P p 11 =( 1 − α k ) P p 1 na =( 1 − α k ) P External AS, if external k and not discovered Cost for discovery, retrieval and NRS update l req ( α k φ c +( p 11 + p 01 ) φ IBS ( +( 1 − p 11 ) φ ori ) , if x k = 1 (2) k Content discovery cost: φ k = l req ( α k φ c + φ FBS +( p 0 na + p 1 na ( 1 − γ FBS )) φ ori ) , if x k = 0 (3) k s k ( α k φ c + p 11 φ IBS ( +( 1 − p 11 ) φ ori ) , if x k = 1 (4) k Content retrieval cost: β k = s k ( α k φ c + p 1 na γ FBS n k φ IBS +( p 0 na + p 1 na ( 1 − γ FBS )) φ ori ) , if x k = 0 (5) k k k ⇢ R k ( ε 1 , ε 0 ) l up φ up , where l up = log K ω + log N + 1, if x k = 1 (6) NRS update cost: ψ k = if x k = 0 0 , (7) 17