Content-Oriented Routing and Its Integration

Transcription

1 September 2011 Content-Oriented Routing and Its Integration with ih IP Infrastructure ETSI Future Network Technologies Workshop 26 September 2011 Sophia Antipolis, France Hang Liu Joint work with Xavier De Foy, Osama Lotfallah, Robert Gazda, and Serhad Doken InterDigital Communications LLC

2 Introduction Problem Statement Content distribution and retrieval is the most dominant use of the Internet and mobile networks Today s IP networking protocols were built to interconnect computing nodes (terminals, servers, etc.) with fixed addresses. As a result, consumers identify and access multimedia content based on where is it stored. But as a consumer, I care about what the content is, not where its stored. Content-oriented t t networking decouples location from identity at the networking level retrieves a content object by its name or identifier, not on its storage location Why Allow client devices to more effectively access contents higher QoE. in-network caching to optimize bandwidth Content delivery from the best location(s) along the best path(s) Allow networks to peer content across domains - reduce congestion access more contents and resources Free application and service developers from reinventing application-specific delivery mechanisms Mobility, multi-homing, content security 2

3 Architecture Built-On (Evolution) Identity and location are separated, but co-exist. Both identifier- and addressbased routing mechanisms are used. Maps the identifier to a location (IP address) at some point in the process of content t access and data delivery via a resolution mechanism Clean-Slate (Revolution) IP addressing and networking is replaced by new identifier-based networking Routing directly uses identifiers, instead of addresses. 3

4 Architecture Comparison Built-On No need for identifier- address mapping Name allocation does not have to be structured only need to ensure uniqueness Greenfield deployment IP address routing has its merits: easy to aggregate, scalable, efficient (shortest path) proven success Infrastructure nodes with IP addressing provides a topology map that can greatly improve identifier-based routing IP-based Internet infrastructure does not go away Incremental deployment for existing infrastructure Clean-Slate 4

5 Standardization Standardization Needs Content naming Content routing protocols How to publish the contents by sources/caches How to locate contents and route content requests Content delivery protocols One to one (anycast) One-to-many (multicast) Many-to-one (multisource, multipath) Many-to-many Cooperative caching Content security 5

6 Content Naming Flat OID Hash of a public key + label or hash of the content data Self-certifying, persistent, unique Need mapping between human-readable name and flat OID, Difficult to aggregate Hierarchical OID Similar to binary encoded URL globally-routable name (domain name) organizational name (volume) versioning or segmentation Prefix-based aggregation like IP address aggregation Not effective as contents are cached at many places Suffix hole Type-Length-Value (TLV) encoded OID consist of a set of variable-size information elements (IE), each IE encoded as a TLV The network imposes no restrictions to the OID assignment except the TLV structure hierarchical or peer relationships location independent and flexible E.g. organizationtlv-authortlv-categorytlv-titletlv-formattlv-segmentationtlv

7 Content OID Aggregation Prefix-based Aggregation: aggregate hierarchical OIDs with the common prefix for scalability The effectiveness of aggregation reduces as content t objects are replicated at multiple locations suffix hole : a host may not have all the content objects for a given prefix. Routing uncertainty duplicate responses or long response Prefix X 7

8 Content OID Summarization To mitigate suffix hole problem, we propose Bloom filter based OID summarization apply Bloom filters on each column of TLV elements to be summarized and generate digest elements. 8

9 Integrated Address and Content ID Networking Identifier-based routing on top of IP routing Infrastructure nodes (routers, base stations) with fixed IP addresses maintain location information of content objects. A content object may be cached at multiple locations and a resolution scheme is used to locate the node that stores a particular content object based on the content object ID (OID) If the IP address is known, the IP routing is used. If a better location for the requested object is available or the IP address is not known, the OID routing is performed. OID is long-term identifier, address is transient IP Header OID Header Content server Cache OID/SOID router IP router Cache OID/SOID router Device Cache OID/SOID router Content server Cache OID/SOID router IP router Cache OID/SOID router Device Signature and signed info Payload OID routing IP routing Dynamic caching Link 1 Link 2 Link 3 9

10 Flooding based Proactive: content host announcing On-demand: discover by flooding each content router builds a routing table {next hop, cost} similar to an IP router Pros a content request and its response can use the same path, Content Request Routing (1) making hop-by-hop transport and in-network caching efficient content OIDs with the same prefix may be aggregated to reduce routing entries. Good for small networks Cons Control overhead Prefix-based aggregation becomes less effective with caching and replication 10

11 Content Request Routing (2) Tree based Each network has a rendezvous () s form hierarchical tree with peered links maps to the Internet hierarchy Content Publish Peering Peering Content PUBLISH propagates up along the tree and among peers Each maintains the location information of all the content objects published in its descendants and peers Mapping of OID to next-hop and distance/cost t to the host of this content t copy Content Request is routed to the closest copy along the tree Simple, but scalability is an issue 11

12 Content Request Routing (3) DHT-Based Map content object IDs to node ID in hash space H(3) H(2) H(OID) OID Hash Key H(OID) H(4) Node n Hash Node mapping identifier H(n) H(1) H(5) Store content location object with key H(OID) in the node whose mapping identifier e H(n) is the closest to and not exceeding H(OID) 12

13 Pros better scalability: share routing burden through distributed lookups No flooding DHT-Based Content Routing Cons Most designs simply adopt the DHT algorithms developed for P2P overlays didn t fully exploit underlying physical network topology => not efficient routing paths are typically several times longer than the optimal route. within a merged hierarchical DHT ring, any node may forward messages to another node that belongs to another ISP, makes it difficult to enforce the ISP policy at the border and even violates the ISP provider-customer rules the paths for the request and response are not symmetric the response may experience a different path from the content request intermediate router does not know whether a content request reaches the final destination and cannot try another route if not. Difficult to handle content OID aggregation due to routing uncertainty and looping 13

14 Our Proposal: New Multi-Level Hierarchical DHT Routing To overcome the shortcomings in DHT-based content routing: We propose a new multi-level hierarchical DHT mechanism with name aggregation exploits underlying intra- and inter-domain IP routing to build multi-level one-hop DHTs Maps to the current Internet hierarchy Efficient and robust ensures the symmetric shortest path and locality for both content requests and responses allows enforcement of the domain policies through delegated border routers. ID summarization at each level scalability 14

15 Infrastructure routers run a link-state IP routing protocol, e.g. OSPF Intra-Domain Content Request Routing provides a network topology: a router knows the existence of all other routers in a routing area one-hop DHT maps a content OID to a router ID When a node caches a content object, generate a location object {OID, publisher IP addr, publication scope, timeout, } Node mapping identifier = Hash (IP addr) Send the location object with H(OID) to the node whose H(IP addr) is the closest to and not exceeding H(OID) => location resolver fast recovery from network failures detected by IP routing Content retrieval Client sends a content request to its delegated router (DR) DR queries location resolver in its DHT ring to get location info forward the Request to the next hop Delegated Router request H(2) H(1) H(3) query request H(OID) H(5) H(4) 15

16 Inter-Domain Content Request Routing Mltiti Multi-tier hierarchical one-hop DHTs BGP content routers (CRs) in peered domains form one-hop DHT Flooding based IP routing + DHT-based identifier routing reflects the Internet hierarchy Content OID PUBLISH propagates up the DHT hierarchy via gateway routers Bloom filter aggregation at each level maintain the first t TLVs of an OID and the remaining N-t TLVs are summarized Summary location object (LO): {summarized OID, publisher IP address, scope, timeout} mapping the summarized OID to a responsible BGP CR in an one-hop DHT a router may say I have the location info of certain contents created by a specific publisher or an author, and their digest is 16

17 Inter-Domain Content Request Routing (Cont.) To retrieve a content object across domains Content Request propagates up through a set of delegated routers (border gateway CRs) A delegated router (DR) resolve the content location by sending a Query to a location resolver in its DHT ring forward the Request to next hop Next hop becomes a DR for this request Forwarding rule: If one matching (summary) LO next hop = the publisher of the (summary) LO If more than one, based on the local policy Forward the Request to all the matching summary LO publishers in parallel or Forward the Request to one of the matching summary LO publishers (closest or most matched digest) If receiving i an error message send the request to the publisher of another matching summary LOs continues until the content object is located or all the matching LOs are tried. 17

18 Content retrieval across domains Inter-Domain Content Request Routing (Cont.) CR9 CR8 Area 3 CR10 Query Content Server 2 ABR3 Backbone Area ABR4 response request Query CR4 CR1 CR3 ABR2 request request ABR1 response response response Query request Query CR 2 Area 1 Area 2 CR5 Client CR 7 CR 6 Content Server 1 18

19 Standardization Aspects Content Naming Flat Hierarchical TLV Aggregation Prefix Bloom filter Content ID routing gprotocols Intra-domain, Inter-domain Flooding (proactive, on-demand) Tree DHT Standardization Bodies ETSI TISPAN, 3GPP, IETF InterDigital will continue developing new technologies and contributing to the standards. Standardization 19 19

20 References T. Koponen et al., A Data-Oriented (and Beyond) Network Architecture, SIGCOMM 07, 2007, pp M. Caesar, T. Condie, J. Kannan, K. Lakshminarayanan, I. Stoica, and S. Shenker, ROFL: Routing on Flat Labels, SIGCOMM, V. Jacobson et al., Networking Named Content, CoNEXT 09, New York, NY, 2009, pp D. Cheriton and M. Gritter, TRIAD: A New Next-Generation Internet Architecture, Technical report, January M. Gritter and D. R. Cheriton, An Architecture for Content Routing Support in the Internet, 3rd Usenix Symp. Internet Technologies and Sys., 2001, pp K. Visala et al., An Inter-Domain Data-Oriented Routing Architecture, Wksp on Rearchitecting the Internet, New York, NY, 2009, pp A. Carzaniga et al., A Routing Scheme for Content-Based Networking, IEEE INFOCOM 04, Hong Kong, China, Mar D. Clark, R. Braden, A. Falk, V. Pingali, FARA: reorganizing the addressing architecture, SIGCOMM FDNA Workshop, August L. Dong, H. Liu, Y. Zhang, S. Paul and D. Raychaudhuri, On the Cache-and-Forward Network Architecture, IEEE ICC L. Fan, P. Cao, J. Almeida, A. Z. Broder, "Summary Cache: A Scalable Wide-Area Web Cache Sharing Protocol", ACM SIGCOMM '98. J. Eriksson, M. Faloutsos, S. Krishnamurthy, PeerNet: Pushing Peer-to-Peer Down the Stack, In IPTPS 03, February 20-21, D. Raychaudhuri, MobilityFirst Vision & Technical Approach Summary, MobilityFirst External Advisory Board Meeting, Feb I. Stoica, D. Adkins, S. Zhuang, S. Shenker, S. Surana, Internet Indirection Infrastructure, ACM SIGCOMM, August J. Choi, et al, A Survey on Content-Oriented Networking for Efficient Content Delivery, IEEE Communications Magazine, March P. Ganesan, K. Gummadi, H. Garcia-Molina, Canon in G major: designing DHTs with hierarchical structure, ICDCS, March I. Stoica, et al, Chord: a scalable peer-to-peer lookup service for Internet applications, SIGCOMM A. Gupta, B. Liskov, and R. Rodrigues, Efficient routing for peer-to-peer overlays, NSDI, March

21 Thank You!