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2011-09-13 AK T-110.6120: Publish/Subscribe Internetworking 1 Evolution vs. Revolution Arto Karila Aalto-HIIT T-110.6120 – Special.

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Presentation on theme: "2011-09-13 AK T-110.6120: Publish/Subscribe Internetworking 1 Evolution vs. Revolution Arto Karila Aalto-HIIT T-110.6120 – Special."— Presentation transcript:

1 AK T : Publish/Subscribe Internetworking 1 Evolution vs. Revolution Arto Karila Aalto-HIIT T – Special Course on Data Communications Software: Publish/Subscribe Internetworking

2 AK T : Publish/Subscribe Internetworking 2 Evolution vs. revolution The Internet has evolved from the 1970’s and with no big changes since 1993 This has led into a stagnated situation where it is very hard to make changes to the core protocols It the Internet was redesigned from scratch, it would probably be very different from what the current Internet has evolved to Various clean-slate solutions are current research topics and some of them may lead into a new Internet It is possible that all the protocol layers, including the Internet Protocol, will change However, any new solution will have to operate as overlay on the existing IP infrastructure to succeed The publish/subscribe paradigm (pub/sub) is one of the most promising new paradigms

3 AK T : Publish/Subscribe Internetworking 3 Some evolutionary approaches A brief look at some evolutionary solutions proposed to the Internet’s shortcomings: IPv6 IPSEC Mobile IP (v4 and v6) HIP DiffServ DHT

4 AK T : Publish/Subscribe Internetworking 4 IPv6 IPv6 was born in 1995 after long work There are over 30 IPv6-related RFCs The claimed improvements in IPv6 are: –Large 128-bit address space –Stateless address auto-configuration –Multicast support –Mandatory network layer security (IPSEC) –Simplified header processing by routers –Efficient mobility (no triangular routing) –Extensibility (extension headers) –Jumbo packets (up to 4 GB)

5 AK T : Publish/Subscribe Internetworking 5 IPv6 Major operating systems and many ISPs support IPv6 The use of IPv6 is slowly increasing in Europe and North America but more rapidly in Asia In China, CERNET 2 runs IPv6, interconnecting 25 points of presence in 20 cities with 2.5 and 10 Gbps links, with each PoP providing 1 to 10 Gbps speeds to an access network ( IPv6 really only solves the exhaustion of Internet address space

6 AK T : Publish/Subscribe Internetworking 6 IPSEC IPSEC is the IP-layer security solution of the Internet to be used with IPv4 and IPv6 Authentication Header (AH) only protects the integrity of an IP packet Encapsulating Security Payload (ESP) also ensures confidentiality of the data IPSEC works within a Security Association (SA) set up between two IP addresses ISAKMP (Internet Security Association and Key Management Protocol) is a very complicated framework for SA mgmt

7 AK T : Publish/Subscribe Internetworking 7 Encapsulating Security Payload (IPv4) Original IPv4 Header Security Parameter Index (SPI) Sequence Number Coverage of Authentication UDP/TCP Header Data Padding Pad Len Next Hdr Authentication Data Coverage of Confidentiality ESP Header ESP Payload ESP Trailer

8 AK T : Publish/Subscribe Internetworking 8 Encapsulating Security Payload (IPv6) ESP Payload Hop-by-Hop Extensions Security Parameter Index (SPI) Sequence Number Coverage of Authentication End-to-End Extensions Data Padding Authentication Data Coverage of Confidentiality ESP Header ESP Trailer Original IPv6 Header UDP/TCP Header

9 AK T : Publish/Subscribe Internetworking 9 Mobile IPv4 Basic concepts: –Mobile Node (MN) –Correspondent Node (CN) –Home Agent (HA) –Foreign Agent (FA) –Care-of-Address (CoA) Problems: –Firewalls and ingress filtering –Triangular routing

10 AK T : Publish/Subscribe Internetworking 10 Mobile IP Triangular Routing Home Agent Correspondent Host Foreign Agent Mobile Host Ingress filtering causes problems for IPv4 (home address as source), IPv6 uses CoA so not a problem. Solutions: (reverse tunnelling) or route optimization Foreign agent left out of MIPv6. No special support needed with IPv6 autoconfiguration DELAY! Care-of-Address (CoA) Source: Professor Sasu Tarkoma

11 AK T : Publish/Subscribe Internetworking 11 Ingress Filtering Home Agent Correspondent Host Packet from mobile host is deemed "topologically incorrect“ (as in source address spoofing) With ingress filtering, routers drop source addresses that are not consistent with the observed source of the packet Source: Professor Sasu Tarkoma

12 AK T : Publish/Subscribe Internetworking 12 HIP Host Identity Protocol (HIP, RFC4423 & others) defines a new global Internet name space The Host Identity name space decouples the name and locator roles, both of which are currently served by IP addresses The transport layer now operates on Host Identities instead of IP addresses The network layer uses IP addresses as pure locators (not as names or identifiers)

13 AK T : Publish/Subscribe Internetworking 13 HIP Architecture Source:

14 AK T : Publish/Subscribe Internetworking 14 HIP HIs are self-certifying (public keys) HIP is a fairly simple technique based on IPSEC ESP and HITs (128-bit HI hashes) It addresses several major issues: –Security –Mobility –Multi-homing –IPv4/IPv6 interoperation HIP is ready for large-scale deployment See for more info

15 AK T : Publish/Subscribe Internetworking 15 Base exchange InitiatorResponder I1HIT I, HIT R or NULL R1HIT I, [HIT R, puzzle, DH R, HI R ] sig I2[HIT I, HIT R, solution, DH I,{HI I }] sig R2[HIT I, HIT R, authenticator] sig ESP protected TCP/UDP, no explicit HIP header User data messages solve puzzle verify, authenticate, replay protection Based on the SIGMA family of key exchange protocols standard authenticated Diffie- Hellman key exchange for session key generation Select precomputed R1. Prevent DoS. Minimal state kept at responder! Does not protect against replay attacks. Source: Dr. Pekka Nikander

16 AK T : Publish/Subscribe Internetworking 16 HIP Mobility Mobility is easy – retaining the SA for ESP

17 AK T : Publish/Subscribe Internetworking 17 HIP in Combining IPv4 and IPv6 IPv4 access network Internet HIP MN Music Server WWW Proxy HIP CN An early demo seen at L.M. Ericsson Finland (source: Petri Jokela, LMF)

18 AK T : Publish/Subscribe Internetworking 18 DiffServ Differentiated Services (DiffServ, RFC 2474) redefines the ToS octet of the IPv4 packet or Traffic Class octet of IPv6 as DS The first 6 bits of the DS field are used as Differentiated Services Code Point (DSCP) defining the Per-Hop Behavior of the packet DiffServ is stateless (like IP) and scales Service Profiles can be defined by ISP for customers and by transit providers for ISPs DiffServ is very easily deployable and could enable well working VoIP and real-time video Unfortunately, it is not used between operators

19 AK T : Publish/Subscribe Internetworking 19 DHT) Distributed Hash Table (DHT) Distributed Hash Table (DHT) is a service for storing and retrieving key-value pairs There is a large number of peer machines Single machines leaving or joining the network have little effect on its operation DHTs can be used to build e.g. databases (new DNS), or content delivery systems BitTorrent is using a DHT The real scalability of DHT is still unproven All of the participating hosts need to be trusted (at least to some extent)

20 AK T : Publish/Subscribe Internetworking 20 DHT The principle of Distributed Hash Table (source: Wikipedia)

21 AK T : Publish/Subscribe Internetworking 21 Some More Revolutionary Approaches 1.ROFL M. Caesar, T. Condie, J. Kannan, K. Lakshminarayanan, I. Stoica, and S. Shenker, ROFL: Routing on Flat Labels, In ACM SIGCOMM, Sep. 2006, pp. 363–374 2.DONA T. Koponen, M. Chawla, B.-G. Chun, A. Ermolinskiy, K. H. Kim, S. Shenker, and I. Stoica, A Data-Oriented (and Beyond) Network Architecture, In SIGCOMM ’07: Proceedings of the 2007 conference on Applications, technologies, architectures, and protocols for computer communications, New York, NY, USA, 2007, pp

22 AK T : Publish/Subscribe Internetworking 22 ROFL ROFL routes directly on host identities, leaving aside the locations of the hosts Self-certifying identifiers (tied to public keys) Create a network layer with no locations Advantages: –No new infrastructure (no name resolution) –Packet delivery only depends on the data path –Simpler allocation of identifiers (just need to ensure uniqueness) –Access control based on identifiers

23 AK T : Publish/Subscribe Internetworking 23 ROFL Three classes of hosts: –Routers –Stable hosts –Ephemeral hosts Each ID is resident to its Hosting Router (the host’s first-hop router) The hosts form a two-way ring – each with pointers to its successor and predecessor There can be shorter routes cached OSPF-like routing protocol (w/ network map) is assumed for recovering from routing failures Global ROFL-ring for inter-domain routing

24 AK T : Publish/Subscribe Internetworking 24 DONA DONA replaces the hierarchical DNS namespace with a cryptographic, self-certifying namespace for naming data This enables entirely distributed namespace control The namespace is not totally flat but consists of two parts: the principal’s identifier and a label This two-tier hierarchy helps make DONA scalable Clean-slate naming and name resolution

25 AK T : Publish/Subscribe Internetworking 25 DONA Strict separation between naming (persistence and authenticity) and name resolution (availability) Each principal has a public-key pair Each datum (or any other named entity) is associated with a principal Names of the form P:L (Principal:Label), where P is a cryptographic hash of the principal’s public key and L is a locally unique label Name resolution by Resolution Handlers, primitives: FIND(P:L), REGISTER(P:L)

26 AK T : Publish/Subscribe Internetworking 26 Networking Named Content Based on: Van Jacobson, V.; Smetters, D. K.; Thornton, J. D.; Plass, M. F.; Briggs, N.; Braynard, R. Networking named content. Proceedings of the 5th ACM International Conference on Emerging Networking Experiments and Technologies (CoNEXT 2009); 2009 December 1-4; Rome, Italy. NY: ACM; 2009; Warm thanks to Van for providing the figures and allowing me to use them!

27 AK T : Publish/Subscribe Internetworking 27 Content-Centric Networking (CCN) CCN – a communication architecture built on named data “Address” named content – not location Preserve the design decisions that make TCP/IP simple, robust and scalable From IP to chunks of named content Only layer 3 requires universal agreement

28 AK T : Publish/Subscribe Internetworking 28 TCP/IP and CCN Protocol Stacks Source: Van Jacobson, PARC, 2009

29 AK T : Publish/Subscribe Internetworking 29 Interest and Data packets There are two types of CCN packets: –Interest packets –Data packets Source: Van Jacobson, PARC, 2009

30 AK T : Publish/Subscribe Internetworking 30 CCN Node Model There are two types of CCN packets: –Interest packets –Data packets Consumer broadcasts its Interest over all available connectivity Data is transmitted only in response to and Interest and consumes that Interest Data satisfies an Interest if ContentName in the Interest is a prefix of that in the Data

31 AK T : Publish/Subscribe Internetworking 31 CCN Node Model Hierarchical name space (cmp w/ URI) When a packet arrives on a face a longest- match lookup is made Forwarding engine with 3 data structures: –Forwarding Information Base (FIB) –Content Store (buffer memory) –Pending Interest Table (PIT)

32 AK T : Publish/Subscribe Internetworking 32 CCN Node Model FIB allows a list of outgoing interfaces – multiple sources of data Content Store w/ LRU or LFU replacement PIT keeps track of Interest forwarded up-stream => Data can be sent downstream Interest packets are routed upstream – Data packets follow the same path down Each PIT entry is a “bread crumb” marking the path and is erased after it’s been used

33 AK T : Publish/Subscribe Internetworking 33 CCN Forwarding Engine Source: Van Jacobson, PARC, 2009

34 AK T : Publish/Subscribe Internetworking 34 CCN Node Model When an Interest packet arrives, longest-match lookup is done on its ContentName ContentStore match is preferred over a PIT match, preferred over a FIB match –Matching Data packet in ContentStore => send it out on the Interest arrival face –Else, if there is an exact-match PIT entry => add the arrival face to the PIT entry’s list –Else, if there is a matching FIB entry => send the Interest up-stream towards the data –Else => discard the Interest packet

35 AK T : Publish/Subscribe Internetworking 35 CCN Transport CCN transport is designed to operate on unreliable packet delivery services Senders are stateless Receivers keep track of unsatisfied Interests and ask again after a time-out The receiver’s strategy layer is responsible for retransmission, selecting faces, limiting the number of unsatisfied Interests, priority One Interest retrieves at most one Data packet => flow balance

36 AK T : Publish/Subscribe Internetworking 36 Reliability and Flow Control Flow balance allows for efficient communication between machines with highly different speeds It is possible to overlap data and requests In CCN, all communication is local and flow balance is maintained over each hop This leads into end-to-end flow control without any end-to-end mechanisms

37 AK T : Publish/Subscribe Internetworking 37 Naming CCN is based on hierarchical, aggregatable names at least partly meaningful to humans The name notation used is like URI Source: Van Jacobson, PARC, 2009

38 AK T : Publish/Subscribe Internetworking 38 Naming and Sequencing An Interest can specify the content exactly Content names can contain automatically generated endings used like sequence #s The last part of the name is incremented for the next chunk (e.g. a video frame) The names form a tree which is traversed in preorder In this way, the receiver can ask for the next Data packet in his Interest packet

39 AK T : Publish/Subscribe Internetworking 39 Intra-Domain Routing Like IPv4 and IPv6 addresses, CCN ContentNames are aggregateable and routed based on longest match However, ContentNames are of varying length and longer than IP addresses The TLV (Type Label Value) of OSPF or IS-IS can distribute CCN content prefixes Therefore, CCN Interest/Data forwarding can be built on existing infrastructure without any modification to the routers

40 AK T : Publish/Subscribe Internetworking 40 Intra-Domain Routing An example of intra-domain routing Source: Van Jacobson, PARC, 2009

41 AK T : Publish/Subscribe Internetworking 41 Inter-Domain Routing The current BGP version has the equivalent of the IGP TLV mechanism Through this mechanism, it is possible to learn which domains serve Interests in some prefix and what is the closest CCN-capable domain on the paths towards those domains Therefore, it is possible to deploy CCN in the existing BGP infrastructure

42 AK T : Publish/Subscribe Internetworking 42 Content-Based Security In CCN, the content itself (rather than its path) is protected One can retrieve the content from the closest source and validate it All content is digitally signed Signed info includes hash of the public key used for signing We still need some kind of a Public Key Infrastructure (PKI)

43 AK T : Publish/Subscribe Internetworking 43 Trust Establishment Associating name spaces with public keys Source: Van Jacobson, PARC, 2009

44 AK T : Publish/Subscribe Internetworking 44 Evaluation The CCN architecture described has been implemented and evaluated Voice over CCN and Content Distribution were tested with small networks The results are interesting but not alone convincing regarding the scalability of the design There still are some fundamental questions that remain unanswered

45 AK T : Publish/Subscribe Internetworking 45 Voice over CCN Secure Voice over CCN was implemented using Linphone 3.0 and its performance evaluated Caller encodes SIP INVITE as CCN name and sends it as an interest On receipt of the INVITE, the callee generates a signed Data packet with the INVITE name as its name and the SIP response as its payload From the SIP messages, the parties derive paired name prefixes under which they write RTP packets There is a separate paper on Voice over CCN

46 AK T : Publish/Subscribe Internetworking 46 Merits of CCN Very simple and understandable scheme Shown to work also with streamed media Clever reuse of existing mechanisms Easy to implement based on current routing software Easy to deploy on existing routing protocols and IP networks Easy, human-readable naming scheme

47 AK T : Publish/Subscribe Internetworking 47 Concerns about CCN The simple hierarchical (URI-like) naming scheme is built deep into the design Will it scale to hundreds of billions of nodes? –Flooding (send out through all available faces) –Flow balance – an Interest for every Data –How large can the FIB grow (soft state)? –Data takes the same (possibly non-optimal) path as Interest – assuming two-way links Are the performance measurements made with only a couple of hosts convincing? Security architecture looks quite conventional

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