What is P2P? Overview P2P-SIP Peer so that peer Internet telephony using SIP

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What is P2P? Overview P2P-SIP Peer so that peer Internet telephony using SIP

Bethel College Mishawaka, US has reference to this Academic Journal, P2P-SIP Peer so that peer Internet telephony using SIP Kundan Singh in addition to Henning Schulzrinne Columbia University, New York June 2005 cs.columbia /IRT/p2p-sip Overview Introduction What is P2P? in addition to SIP? Why P2P-SIP? Architecture SIP using P2P vs P2P over SIP; Components that can be P2P Implementation Choice of P2P (DHT); Node join, leave; message routing Conclusions in addition to future work Total 33 slides What is P2P? Share the resources of individual peers CPU, disk, bandwidth, information, ?

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P2P goals Resource aggregation – CPU, disk, ? Cost sharing/reduction Improved scalability/reliability Interoperability – heterogeneous peers Increased autonomy at the network edge Anonymity/privacy Dynamic (join, leave), self organizing Ad hoc communication in addition to collaboration Definition fuzzy both client in addition to server? true in consideration of proxy no need in consideration of central server true in consideration of SIP-based media SIP can be e2e proxy functions distributed among end systems Distributed Hash Table (DHT) Types of search Central index (Napster) Distributed index alongside flooding (Gnutella) Distributed index alongside hashing (Chord) Basic operations find(key), insert(key, value), delete(key), but no search(*) Why P2P-SIP? Bob?s host Alice?s host 128.59.19.194 REGISTER alice@columbia =>128.59.19.194 INVITE alice@columbia Contact: 128.59.19.194 columbia Client-server=> maintenance, configuration, controlled infrastructure

How so that combine SIP + P2P? SIP-using-P2P Replace SIP location service by a P2P protocol P2P-over-SIP Additionally, implement P2P using SIP messaging P2P network Alice 128.59.19.194 INSERT INVITE sip:alice@128.59.19.194 P2P-SIP overlay Alice 128.59.19.194 REGISTER INVITE alice FIND SIP-using-P2P Reuse optimized in addition to well-defined external P2P network Define P2P location service interface so that be used in SIP Extends so that other signaling protocols P2P-over-SIP P2P algorithm over SIP without change in semantics No dependence on external P2P network Reuse in addition to interoperate alongside existing components, e.g., voicemail Built-in NAT/media relays Message overhead

Today?s Topics: 1 . Proof by contraposition Proof by contraposition Truth table in consideration of implication Example Example Example Example Example 2 . Proof by cases Breaking a proof into cases Breaking a proof into cases Breaking a proof into cases Breaking a proof into cases Breaking a proof into cases Breaking a proof into cases Breaking a proof into cases

What else can be P2P? Rendezvous/signaling Configuration storage Media storage Identity assertion (?) Gateway (?) NAT/media relay (find best one) Our P2P-SIP approach Unlike server-based SIP architecture Unlike proprietary Skype architecture Robust in addition to efficient lookup using DHT Interoperability DHT algorithm uses SIP communication Hybrid architecture Lookup in SIP+P2P Unlike file-sharing applications Data storage, caching, delay, reliability Disadvantages Lookup delay in addition to security Background: DHT (Chord) Identifier circle Keys assigned so that successor Evenly distributed keys in addition to nodes Finger table: logN ith finger points so that first node that succeeds n by at least 2i-1 Stabilization in consideration of join/leave 1 8 14 21 32 38 58 47 10 24 30 54 38 42

Design alternatives Use DHT in server farm Use DHT in consideration of all clients – but some are resource limited Use DHT among super-nodes Hierarchy Dynamically adapt servers clients 1 10 24 30 54 38 Architecture of prototype On startup Multicast REGISTER Peer found/ Detect NAT REGISTER REGISTER, INVITE, MESSAGE Signup, Find buddies Join Find Leave On reset Signout, transfer IM, call SIP-over-P2P P2P-using-SIP Naming in addition to authentication SIP URI as node in addition to user identifiers Known node: sip:15@192.2.1.3 Unknown node: sip:17@example User: sip:alice@columbia User name is chosen randomly by the system, by the user, or as user?s email Email the randomly generated password TTL, security

SIP messages DHT (Chord) maintenance Query the node at distance 2k alongside node id 11 REGISTER To: From: SIP/2.0 200 OK To: Contact: ; predecessor=sip:10@128.59.15.55 Update my neighbor about me REGISTER To: Contact: ; predecessor=sip:1@128.59.15.60 1 10 15 22 Find(11) gives 15 7 SIP messages User registration REGISTER To: sip:alice@columbia Contact: sip:alice@128.59.19.194:8094 Call setup in addition to instant messaging INVITE sip:bob@example To: sip:bob@example From: sip:alice@columbia Node startup SIP REGISTER alongside SIP registrar DHT Discover peers: multicast REGISTER SLP, bootstrap, host cache Join DHT using node-key=Hash(ip) Query its position in DHT Update its neighbors Stabilization: repeat periodically User registers using user-key=Hash(alice@columbia ) alice@columbia REGISTER Detect peers columbia 14 32 58 12 42 REGISTER alice=42 REGISTER bob=12

Node leaves Chord reliability Log(N) successors, replicate keys Graceful leave Un-REGISTER Transfer registrations Failure Attached nodes detect in addition to re-REGISTER New REGISTER goes so that new super-nodes Super-nodes adjust DHT accordingly DHT REGISTER key=42 OPTIONS 42 42 REGISTER Implementation sippeer: C++, Unix (Linux), Chord Node join in addition to form the DHT Node failure is detected in addition to DHT updated Registrations transferred on node shutdown 31 15 29 25 31 26 Adaptor in consideration of existing phones Use P2P-SIP node as an outbound proxy ICE in consideration of NAT/firewall traversal STUN/TURN server in the node

Hybrid (federated) architecture Cross register, or Locate during call setup DNS, or P2P-SIP hierarchy Evaluation scalability #messages depends on Keep-alive in addition to finger table refresh rate Call arrival distribution User registration refresh interval Node join, leave, failure rates M={rs+ rf(log(N))2} + c.log(N) + (k/t)log(N) + ?(log(N))2/N #nodes = f(capacity,rates) CPU, memory, bandwidth Verify by measurement in addition to profiling Evaluation reliability in addition to call setup latency User availability depends on Super-node failure distribution Node keep-alive in addition to finger refresh rate User registration refresh rate Replicate user registration Measure effect of each Call setup latency Same as DHT lookup latency: O(log(N)) Calls so that known locations (?buddies?) is direct DHT optimization can further reduce latency User availability in addition to retransmission timers Measure effect of each

P2P vs. server-based SIP Prediction: P2P in consideration of smaller & quick setup scenarios Server-based in consideration of corporate in addition to carrier Need federated system multiple p2p systems, identified by DNS domain name alongside gateway nodes 2000 requests/second ?7 million registered users Explosive growth (further study) Cache replacement at super-nodes Last seen many days ago Cap on local disk usage (automatic) Forcing a node so that become super node Graceful denial of service if overloaded Switching between flooding, CAN, Chord, ? . . . More open issues (further study) Security Anonymity, encryption Attack/DOS-resistant, SPAM-resistant Malicious node Protecting voicemails from storage nodes Optimization Locality, proximity, media routing Deployment SIP-P2P vs P2P-SIP, Intra-net, ISP servers Motivation Why should I run as super-node?

Comparison of P2P in addition to server-based systems Catastrophic failure Server redundancy is well-understood ? can handle single-server failures Catastrophic (system-wide) failure occurs when common element fails Both server-based in addition to P2P: all servers crash based on client stimulus (e.g., common parser bug) Traditional server-based system: servers share same facility, power, OS, ? P2P system less likely share same OS? Conclusions P2P useful in consideration of VoIP Scalable, reliable No configuration Not as fast as client/server P2P-SIP Basic operations easy Implementation sippeer: C++, Linux Interoperates Some potential issues Security Performance cs.columbia /IRT/p2p-sip p2psip /

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Journal Ratings by Bethel College Mishawaka

This Particular Journal got reviewed and rated by P2P vs. server-based SIP Prediction: P2P in consideration of smaller & quick setup scenarios Server-based in consideration of corporate in addition to carrier Need federated system multiple p2p systems, identified by DNS domain name alongside gateway nodes 2000 requests/second ?7 million registered users Explosive growth (further study) Cache replacement at super-nodes Last seen many days ago Cap on local disk usage (automatic) Forcing a node so that become super node Graceful denial of service if overloaded Switching between flooding, CAN, Chord, ? . . . More open issues (further study) Security Anonymity, encryption Attack/DOS-resistant, SPAM-resistant Malicious node Protecting voicemails from storage nodes Optimization Locality, proximity, media routing Deployment SIP-P2P vs P2P-SIP, Intra-net, ISP servers Motivation Why should I run as super-node? and short form of this particular Institution is US and gave this Journal an Excellent Rating.