RELOAD P2P Overlay Access Protocol. Younghan Kim Soongsil University

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1 RELOAD P2P Overlay Access Protocol Younghan Kim Soongsil University

2 Contents Introduction What is P2P? Why P2P-SIP? P2PSIP overlay network Architecture Operations RELOAD protocol Introduction Protocol structure Usages for RELOAD protocol SIP usage Distributed conference control (DisCo) Service Discovery Other IETF P2P WGs 2

3 What is P2P? Centralized mainframes workstations Computer systems Client-server Distributed Peer-to-peer Share the resources of individual peers CPU, disk, bandwidth, information, Communication and collaboration Magi Groove Skype Flat Hierarchical Pure Hybrid C C RPC HTTP S DNS mount C C Gnutella Chord P P Kazaa Napster Groove P P SETI@Home folding@home Napster Gnutella Kazaa Freenet Overnet File sharing C P Distributed computing 3

4 Why P2P-SIP? INVITE REGISTER => Bob s host Contact: ssu.ac.kr Alice s host Client-server => maintenance, configuration, controlled infrastructure INVITE Alice P2P overlay REGISTER Bob No central server, search latency Alice

5 How to combine SIP + P2P? SIP-using-P2P Replace SIP location service by a P2P protocol Use two separate stacks: a SIP layer for registering users, resource lookup, establishing session, and a P2P layer for maintaining a distributed network P2P-over-SIP SIP messages are used for registering users, resource lookup, establishing session, also used for maintaining a P2P network SIP is mature, using SIP as foundation and carry out P2P traffic on top of it => not cost extra stack and not require much change of SIP itself P2PSIP WG FIND P2P network INSERT INVITE Alice P2P-SIP overlay REGISTER Bob INVITE sip:alice@ Alice Bob Alice

6 The architecture of P2P-SIP overlay network UA Peer E PSTN NAT / Firewall UA Peer F P2PSIP Overlay Gateway Peer G RELOAD P2PSIP Protocol UA Client C NAT / Firewall Peer Q Bootstrap Server Enrollment Server RELOAD P2PSIP Protocol UA Peer D SIP Proxy Peer P SIP domain SIP Redirect Peer R SIP UA A SIP UA B (*) draft-ietf-p2psip-concepts-03 October

7 Component definitions Peer: A node in overlay that provides storage and transport services to other nodes in that P2PSIP overlay Client: A node in overlay does not store information or forward messages Overlay name: a human-friendly name identifies a specific P2PSIP overlay Service: a capability contributed by a peer to an overlay or to the members of an overlay Peer protocol: the protocol used between P2PSIP overlay peers to share information and organize the P2PSIP overlay network Client protocol: the protocol used between clients and peers Enrollment server: provide peer-id and credentials for joining peer 7

8 P2PSIP overlay operations The joining procedure Joining Peer Bootstrap Server Bootstrap Peer Admitting Peer Joining Peer 5 Overlay information exchange P2PSIP Overlay ssu.ac.kr Bootstrap Peer Admitting Peer (5) (3) Credentials (1) & (4) (2) ICE Enrollment Server Joining Peer Bootstrap Server REGISTER (1) (2) ICE (3) (5) Credentials INVITE 200 OK ACK BYE/200 OK REGISTER INVITE 200 OK ACK ICE Connectivity Checks Peer Ptotocol connection from A to C established INVITE (Replaces) 200 OK ACK BYE/200 OK Overlay information exchange INVITE 200 OK ACK BYE/200 OK 8

9 The resource registration procedure Peer A (3) 200 OK P2PSIP Overlay (ssu.ac.kr) (3) 200 OK Peer C Peer B sip:alice@ssu.ac.kr (1) REGISTER (2) REGISTER (forward) P2P SIP Peer C is responsible of the mapping to sip:alice@ssu.ac.kr, because the URI hashes to its key space part (1) Standard SIP REGISTER message is sent to the overlay (2) Routing mechanism of the overlay handles to forward the message to peer responsible for the resource-id (Peer C) (3) On the reverse path, responsible peer sends 200 OK message to the peer providing the resource 9

10 P2PSIP Lookup SIP session establishment NAT P2P SIP NAT P2P SIP P2P SIP A P2P SIP P2P SIP A P2P SIP sip:bob@ssu.ac.kr P2PSIP Overlay (ssu.ac.kr) (3) 200 OK (bob (3) 200 OK (2) REGISTER (forward) (1) REGISTER (for resource lookup) B sip:bob@ssu.ac.kr (2) ICE (3) 200 OK P2PSIP Overlay (3) Media (ssu.ac.kr) (1) INVITE bob@ssu.ac.kr (3) 200 OK (1) INVITE (bob (forward) (2) REGISTER (forward) (1) REGISTER (for resource lookup) B P2P SIP NAT D C Peer C is responsible of the mapping to sip:bob@ssu.ac.kr, because it hashes to its key space part P2P SIP NAT D C 10

11 P2PSIP Peer Protocol (RELOAD) The first goal of P2PSIP WG is to develop and standardize a P2PSIP peer protocol This protocol is used between P2PSIP overlay peers, and define how the P2PSIP peers collectively provide for user and resource location in a SIP environment with no or minimal centralized servers Provide a distribution location service for RFC 3263 (locating SIP servers). The location service determines the correct destination of SIP requests without centralized servers, using only peers Resource Location And Discovery (RELOAD) protocol is proposed 11

12 RELOAD Introduction REsource LOcation And Discovery (RELOAD) A peer-to-peer (P2P) signaling protocol for use on the Internet Provides a generic, self-organizing overlay network service, allowing nodes to efficiently route messages and to efficiently store and retrieve data in the overlay. RELOAD provides several features Security Framework: central enrollment server. Usage Model: support a variety of applications, or new application usages (own data types, its rules). NAT Traversal: using ICE. High Performance Routing: a simple, lightweight forwarding header. Pluggable overlay Algorithms: a variety of structured (DHT) and unstructured overlay algorithms. (*) draft-ietf-p2psip-base-13 March

13 Architecture Usage Layer: each application defines a RELOAD usage (set of data kinds and behaviors that describe how to use the services provided by RELOAD) Message Transport: handles end-to-end reliability. Storage: processing messages relating to the storage and retrieval of data. Topology Plug-in: implement the specific overlay algorithm. Forwarding and Link Management Layer: store and implement routing table, establish new links (NAT using ICE) Overlay Link Layer: transporting traffic directly between nodes SIP Usage Message Transport Application XMPP Usage Forwarding & Link Management TLS DTLS... Storage Topology Plugin CHORD... Messaging API Overlay Link API 13

14 Message Transport Provides a generic message routing service for the overlay Each peer is identified by its location in the overlay as determined by its Node-ID Two basic functions that a component which is a client of the Routing Layer can perform : Send a message to a given peer, specified by Node-Id or responsible for a Resource-Id Receive messages that other peers sent to a Node-Id or Resource-Id for which this peer is responsible SIP Usage Message Transport Application XMPP Usage Forwarding & Link Management TLS DTLS... Messaging API Storage Topology Plugin CHORD... Overlay Link API 14

15 Storage and Topology Plug-in Storage Responsible for processing messages relating to the storage and retrieval messages from other peers A peer s Node-ID determines the set of resources that it will be responsible for storing Topology Plug-in 15 Responsible for implementing and maintaining the specific overlay algorithm being used SIP Usage Message Transport Application XMPP Usage Forwarding & Link Management TLS DTLS... Messaging API Storage Topology Plugin CHORD... Overlay Link API

16 Forwarding & Link Management Layer Responsible for getting a packet to the next peer, as determined by the Routing and Storage Layer Establishes and maintains the network connections as required by the Topology Plug-in Allows the topology plug-in to control the overlay and resource operations and messages. Responsible for setting up connections to other peers through NATs and firewalls using ICE Utilizes a framing header to encapsulate messages as they are forwarding along each hop. SIP Usage Message Transport Application XMPP Usage Forwarding & Link Management TLS DTLS... Messaging API Storage Topology Plugin CHORD... Overlay Link API 16

17 Data Storage Each kind is identified by a kind-id Base Routing Scheme Symmetric Recursive Protocol designers may define constraints Limits on size, on the values which may be stored Resource-ID Kind 1 Kind 2 Value Value Value Value Value 17

18 P2PSIP Integration Overview The SIP Usage of RELOAD allows SIP user agents to provide a peer-to-peer telephony service without the requirement for permanent proxy or registration servers The RELOAD overlay itself performs the registration and rendezvous functions The basic function of the SIP usage To allow Alice to start with a SIP URI (e.g., "bob@dht.ssu.ac.kr") End up with a connection which Alice's SIP UA can use to pass SIP messages back and forth to Bob's SIP UA The example of this is shown on next page 18

19 An SIP usage for RELOAD Peer Alice (5678) Peer1 Overlay Peer2 Peer Bob (1234) 1. Bob, operating Node-ID 1234, stores a mapping from his URI to his Node-ID in the overlay I.e., "sip:bob@dht.ssu.ac.kr -> 1234" Connect Connect Connect 2. Alice, operating Node-ID 5678, ConnectAns ConnectAns ConnectAns decides to call Bob. She looks up "sip:bob@dht.ssu.ac.kr" in the overlay ICE Checks INVITE OK ACK and retrieves "1234" 3. Alice uses the overlay to route a ICE Checks for media Connect message to Bob's peer RTP Bob responds with his own Connect and they set up a direct connection 19

20 RELOAD Message Flow Example JP PPP PP AP NP NNP BP Attach Dest = JP Attach Dest = JP Attach Dest = JP AttachAns AttachAns AttachAns TLS PPP PP JP: Joining Peer AP: Admitting Peer PP: Previous Peer (before AP) NP: Next Peer (after AP) BP 2.Attach Dest = JP 5.AttachAns 1.Attach Dest = JP 6.AttachAns 3.Attach Dest = JP 4.AttachAns AP NP JP NNP 20

21 PPP PP JP 4.AttachAns 1.Attach AP+1 AP BP NP 3.AttachAns 2.Attach AP+1 NNP JP PPP PP AP NP NNP BP Attach AP+1 Attach AP+1 AttachAns AttachAns TLS 21

22 XX PPP PP AP 1.JoinReq 4. StoreAns 6. StoreAns 8. UpdateAns JP 2. JoinAns 3.StoreReq Data A 5. StoreReq Data B 7. UpdateReq TP NP NNP JP PPP PP AP NP NNP JoinReq JoinAns StoreReq Data A StoreAns StoreReq Data B StoreAns UpdateReq UpdateAns 22

23 JP PPP PP AP NP NNP Attach Dest=PP AttachAns TLS UpdateReq Attach Dest=PP AttachAns UpdateAns UpdateReq UpdateAns UpdateReq UpdateAns 23

24 A RELOAD Usage for Distributed Conference Control (DisCo) User Agent E Peer C SIP SIP Access List Focus Peer A Storing Peer SP RELOAD Instance Conf. Events Call delegation Reference Model DisCo-Registration Focus Peer B Peer D Overlay Comm. Client F (*) draft-knauf-p2psip-disco-02, March 2011 SIP Peers A and B managing a single multiparty conference, fulfilling the role of the focus The storing peer SP of the distributed conference resource holds a mapping of conference URI to the responsible focus peers Focus peers maintain SIP signaling relations to conference participants: Peer A is the focus for the RELOAD peer C and plain user agent E Peer B is the focus for RELOAD peer D and RELOAD client F 24

25 Joining a Conference (initiating peer) RELOAD (joining peer) Store mapping (ConfURI, Alice) Alice stores her mapping to register a conference Lookup ConfURI Bob requests the list of potential focus peers Result list of conf. focus Bob establishes transport connection to Alice AppAttach AppAttach INVITE OK ACK Media Store mapping(confuri, Bob) Bob stores his mapping to become a focus peer too 25

26 Service Discovery Usage for K V RELOAD K 1 : a particular service V 1 : Peer-ID K V K V K V k 1,v 2 k 1,v 1 K V k 1,v 3 list(v 1 V 2 V 3 ) k 1 K V K V store(k 1,v 1 ) K V store(k 1,v 3 ) store(k 1,v 2 ) General service discovery mechanism: a peer wants to use a particular service S (key=k1) will find peers that are providing that service from the Overlay (Peer-ID: v1, v2, v3) K V K V req(k 1 ) 26

Motivation of a new service discovery mechanism The limitation of this general mechanism: scales linearly in case the number of nodes that provide the service largely, leading the problems: The Node

27 Motivation of a new service discovery mechanism The limitation of this general mechanism: scales linearly in case the number of nodes that provide the service largely, leading the problems: The Node X is responsible for service S(key k) becomes traffic overloaded easily, because all service lookup requests for service s are answered by node X Doesn t provide load balancing between nodes in overlay that providing a service Defining a service discovery mechanism for base protocol in P2PSIP wg (RELOAD): Using Recursive Distributed Rendezvous (ReDir) service discovery mechanism used in OpenDHT applied to RELOAD overlays ReDir builds a tree structure of nodes that provide a particular service, then embedding into the RELOAD overlay 27

28 The DHT accessed as a Service in OpenDHT CFS (MIT) PAST (MSR/ Rice) OStore (UCB) psearch (HP) Coral (NYU) i3 (UCB) PIER (UCB) Overnet (open) Chord DHT Pastry DHT Tapestry DHT CAN DHT Kademlia DHT Chord DHT Bamboo DHT Kademlia DHT indirection DHT Every application deploys its own DHT (DHT as a library) OpenDHT: one DHT, shared across applications (DHT as a service) connectivity IP 28

29 OpenDHT architecture Interface (Puts/Gets) Infrastructure nodes run the OpenDHT server code. Client nodes are outside the set of infrastructure nodes and access DHT using RPC over TCP Client OpenDHT Client Interface is simple put/get: Put(key/value) stores value under key Get(key) returns all the values stored under key Client Client 29

30 Recursive Distributed Rendezvous (ReDiR) put/get interface cannot meet the needs of some applications using another DHT interface: lookup Goal: Implement two functions using put/get: join(namespace, node) node = lookup(namespace, identifier) Procedure Functionality Join(host, id, namespace) adds(host, id) to the list of hosts providing functionality of namespace Lookup(key, namespace) returns(host, id) in namespace whose id most immediately follows key The lookup interface provided using ReDiR 30

31 Recursive Distributed Rendezvous (ReDiR) Each service provided in the overlay has established own ReDiR tree Each service provided in the overlay is identified by an identifier, namespace ns Each tree node in ReDiR tree contains a list of node-id providing a service At level 0: node (0,0) responsible for two intervals Level 1: two nodes (1,0), (1,1), each of which is responsible for half of the id space Level 2, 3, interval for keyspace Level 0 Level 1 Level 2 Level 3 ReDiR tree 31

32 Other P2P WGs related in IETF PPSP: Peer to Peer Streaming Protocol ALTO: Application-Layer Traffic Optimization DECADE: Decoupled Application Data Enroute (*) draft-seedorf-ppsp-design-considerations-02, April 2011 (*) draft-gu-ppsp-tracker-protocol-03, March 2011 (*) draft-ietf-alto-protocol-07, March 2011 (*) draft-ietf-decade-arch-00, March

protocol: among the peers Tracker Request Data Networks PPSP Transmission and return A/B/C Register Data Networks Chunk

33 PPSP WG Peer-to-peer Streaming Protocol (PPSP) WG develops two signaling and control protocols for a P2P streaming system for transmitting live media content that satisfy real-time delivery constraints: Tracker protocol: between trackers and peers Peer protocol: among the peers Tracker Request Data Networks PPSP Transmission and return A/B/C Register Data Networks Chunk Description, A Peer List, Peer Status, etc. Requestor Chunk Data B Content Registration and/or Peer List Request PPSP Signaling Swarm C 33

34 Tracker protocol components Peer Peer signaling CONNECT/ DISCONNECT/JOIN/ JOIN_CHUNK/LEAVE/FI ND/ KEEPALIVE/ STAT_REPORT Communication Layer Data management Swarm ID -Chunk ID -Peer list -Buffer map Tracker Tracker signaling JOIN/LEAVE/ KEEPALIVE/PUT/G ET/STAT_QUERY/ STAT_REPORT Peer status Peer ID Online time Peer property Link status Data management on Tracker Content status Swarm ID Chunk ID Peer list 34

35 Flow of Peer protocol 35

ALTO WG Design and specify an application-layer traffic optimization (ALTO) service that provide applications by perform better-than-random initial peer selection ALTO Protocol

36 ALTO WG Design and specify an application-layer traffic optimization (ALTO) service that provide applications by perform better-than-random initial peer selection ALTO Protocol defines communication between ALTO Client and ALTO Server ALTO Client Routing Protocols ALTO Server Provisioning Policy ALTO Service Discovery ALTO Protocol Dynamic Network Info... 36

37 ALTO Service Model ALTO Server provides ALTO Information to ALTO Clients Indicates preferences amongst Resource Consumers and Resource Providers ALTO Client (P2P Client) ALTO Client (P2P Tracker) Resource Consumers and Providers ALTO Server 37

38 ALTO (Application-Layer Traffic Optimization) A request/response protocol for querying the ALTO service to obtain information useful for peer selection 38

39 DECADE WG DECADE intended to improve network efficiency of P2P apps Storage Storage by introducing storage into the Network network Develop an architecture for accessing in-network storage Standard Protocol Standard Protocol WG identifies the requirements to enable target applications to utilize in-network storage P2P Peer P2P Protocols Peer P2P Peer 39

40 Architectural entities: applications Typical characteristics: Divide content into smaller objects for distribution Multiple sources for content 40

41 Q & A Thank you! 41

P2PSIP, ICE, and RTCWeb

P2PSIP, ICE, and RTCWeb T-110.5150 Applications and Services in Internet October 11 th, 2011 Jouni Mäenpää NomadicLab, Ericsson Research AGENDA Peer-to-Peer SIP (P2PSIP) Interactive Connectivity Establishment