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IETF-72 P2PSIP Routing Modes

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IETF-72 P2PSIP Routing Modes

  1. 1. Discussion On Routing Modes IETF72 P2PSIP WG draft-jiang-p2psip-sep-01 <ul><li>Jiang XingFeng Jiang.x.f@huawei.com </li></ul><ul><li>Carlos Macian carlos.macian@upf.edu </li></ul><ul><li>Victor Pascual victor.pascual@tekelec.com </li></ul>
  2. 2. Routing Modes <ul><li>Symmetric Recursive </li></ul><ul><ul><li>Request and corresponding response follow the same path; </li></ul></ul><ul><ul><li>Adopted in the current RELOAD draft </li></ul></ul><ul><li>Direct Response </li></ul><ul><ul><li>Send response directly back if the requesting peer allows it (e.g. it is publicly reachable) </li></ul></ul><ul><li>Relay Peer </li></ul><ul><ul><li>With help from relay peers with unrestricted connections, the response could go through the relay peer to reach the request originator </li></ul></ul><ul><li>Forward Response </li></ul><ul><ul><li>Response is considered as a distinct transaction from request and routed through the overlay based on the Node ID of request originator, (i.e. routing based on the underlying P2P algorithm) </li></ul></ul><ul><li>Iterative </li></ul><ul><ul><li>where the intermediate peers merely return a response indicating the next hop, but do not actually forward the message to that next hop themselves </li></ul></ul>
  3. 3. Why Relay Peer And Direct Response? Improve Success Rate <ul><li>NOT meant to REPLACE symmetric recursive </li></ul><ul><ul><li>Enhancement to symmetric recursive </li></ul></ul><ul><ul><li>Could work together with symmetric recursive </li></ul></ul><ul><li>Main Benefit </li></ul><ul><ul><li>Reduce the number of hops of response path to </li></ul></ul><ul><ul><ul><li>Number of hops = 1 - Direct Response </li></ul></ul></ul><ul><ul><ul><li>Number of hops = 2 - Relay Peer </li></ul></ul></ul><ul><ul><li>Improve success rate of P2PSIP transaction </li></ul></ul>
  4. 4. Where Is Relay/Direct Response Helpful? Dynamic Scenarios <ul><li>Concerns about routing in P2P systems </li></ul><ul><ul><li>Node’s stability </li></ul></ul><ul><ul><li>Connectivity stability between peers </li></ul></ul><ul><li>Where Symmetric MAY NOT Work Well </li></ul><ul><ul><li>Heavy churn </li></ul></ul><ul><ul><li>Path with larger hop count </li></ul></ul><ul><ul><ul><li>The number of hops often follows a uniform distribution within [0, M]; M: lookup complexity of the specific algorithm in use </li></ul></ul></ul><ul><ul><ul><li>Symmetric works well with smaller hop count </li></ul></ul></ul><ul><ul><li>Stability of TURN peers has an impact on the connectivity stability between peers </li></ul></ul><ul><ul><li>Overlays with large scales, for example, over 1000 peers </li></ul></ul>
  5. 5. How Relay Peer Works - 1 A B C D Z X Y Request Originator Intermediate Peer Destination Peer Relay Peer Pre-established connection 1 2 3 4 5 5 5 6 7 8 Request Symmetric Recursive Relay Peer
  6. 6. How Relay Peer Works - 2 <ul><li>A typical message sequence </li></ul><ul><ul><li>Originator discovers relay peers first </li></ul></ul><ul><ul><li>Originator carries info about relay peers in the request to be routed around the overlay </li></ul></ul><ul><ul><li>Destination peer sends the responses to the relay peers which forwards the response toward the request originator </li></ul></ul><ul><li>When Relay Peer is triggered </li></ul><ul><ul><li>The destination peer decides whether or not Relay Peer is used </li></ul></ul><ul><ul><li>Possible criteria </li></ul></ul><ul><ul><ul><li>The request has traversed so many hops that it is highly probable that one of reverse connections broke down </li></ul></ul></ul>
  7. 7. Concerns – Relay Peer <ul><li>Relay Peer </li></ul><ul><ul><li>Considered as a kind of service, just like STUN/TURN service; </li></ul></ul><ul><ul><li>Unrestricted connection – Identify Relay Peer </li></ul></ul><ul><ul><ul><li>Possible to decide whether a peer is on the public Internet in P2PSIP, for example, with the help from bootstrap peer or enrollment server who are already on public Internet; </li></ul></ul></ul><ul><ul><ul><li>While being on the public Internet, a peer can use Direct Response to determine whether or not it is behind a firewall or address-independent firewall; </li></ul></ul></ul>
  8. 8. Concerns – DoS Attack <ul><li>Attack 1 </li></ul><ul><ul><li>A large number of responses are sent to the Relay peer to overload the Relay peer </li></ul></ul><ul><ul><ul><li>Relay peer only forwards response to the peer with whom (peer) it has direct connections; </li></ul></ul></ul><ul><li>Attack 2 </li></ul><ul><ul><li>Malicious peers send a great number of requests and indicate to use a Relay Peer to route responses besides using symmetric recursive routing , which will amplify the number of the response to the request originator </li></ul></ul><ul><ul><ul><li>Destination peer will base response on some criteria treated as a parameter, such as total hops the request’s traversed, to decide whether relay peers are used to route the response; </li></ul></ul></ul><ul><ul><ul><li>This mitigates the impact from the response amplification </li></ul></ul></ul>
  9. 9. Next Step <ul><ul><li>Adopted as a WG item (Direct Response and Relay Peer)? </li></ul></ul><ul><li>Or </li></ul><ul><ul><li>The choice of Routing modes be a open issue and need more investigation? (including symmetric recursive) </li></ul></ul>

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