>
 
   
 
Peer-to-peer 
 systems for autonomic VoIP and web hotspot handling 
 
 
Kundan Singh, Weibin 
 Zhao and Henning Schulzrinne
 
Internet Real Time 
 Laboratory
 
Computer Science 
 Dept., Columbia University, New York
 

     
       identifier lookup
       NAT traversal: media 
       traversal
       
     OpenDHT (and similar) 
     as emerging common infrastructure?
     Non-DHT systems with 
     smaller scope 00web hotspot rescue
     Network management 
     (see our IRTF slides)
 
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
3  
 
 
Aside: 
 autonomic characteristics 
 
   Autonomic characteristics 
   (self-*) determine success for consumer applications:
   
     web-based email programs
     consumer IM
     Skype
     Apple Rendezvous, DHCP
     
   IETF and IEEE slowly 
   starting to take note:
   
     old techniques (ICMP) 
     no longer working
     netconf: XML-based 
     network configuration instead of CLI and (rarely) SNMP
     XCAP: generic XML configuration 
     manipulation
     SIP auto-configuration 
     work
     IEEE 802.1 network 
     discovery (LLDP, 00
     concerns about network 
     complexity
 
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
4  
 
 
What 
 is SIP? Why P2P-SIP? 
 
Bob00 host 
 
 
Alice00 host
 
128.59.19.194 
 
 
(1) REGISTER
 
      
 alice@columbia.edu =>128.59.19.194 
 
(2) INVITE  alice@columbia.edu 
 
 
(3) Contact: 128.59.19.194 
 
 
columbia.edu 
 
Problem in client-server: 
 maintenance, configuration, controlled infrastructure 
 
 
Peer-to-peer network 
 
 
Alice
 
128.59.19.194 
 
 
(1) REGISTER 
 
(2) INVITE alice 
 
 
(3) 128.59.19.194 
 
 
No central server, but 
 more lookup latency
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
5  
 
 
How 
 to 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 
 
 
SIP 
 
 
P2P 
 
 
Lookup 
 
SIP 
 
 
P2P 
 
 
P2P 
 
 
Maintenance 
 
 
P2P-over-SIP 
 
 
P2P 
 SIP proxies 
 
SIP-using-P2P
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
6  
 
 
Deployment 
 scenarios 
 
P 
 
P 
 
P 
 
P 
 
P 
 
P2P proxies 
 
P 
 
P 
 
P 
 
P 
 
P 
 
P2P database 
 
P 
 
P 
 
P 
 
P 
 
P 
 
P2P clients 
 
Plug and play; 
 
May use adaptors;
 
Untrusted peers 
 
Zero-conf server farm; 
 
Trusted servers and 
 
user identities 
 
Global, e.g., OpenDHT; 
 
Clients or proxies can use;
 
Trusted deployed peers (?) 
 
 
Interoperate among these!
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
7  
 
 
Hybrid 
 architecture 
 
   Cross register, or 
   Locate during call 
   setup
   
     DNS, or
     P2P-SIP hierarchy
 
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
8  
 
 
What 
 else can be P2P? 
 
   Rendezvous/signaling 
   (SIP)
   Configuration storage
   Media storage (e.g., 
   voice mail)
   Identity assertion 
   (?)
   PSTN gateway (?)
   NAT/media relay 
   (find best one) 
 
  
 
Trust models are different 
 for different components!
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
9  
 
 
What 
 is our P2P-SIP? 
 
   Unlike 
   server-based SIP architecture
   Unlike proprietary 
   Skype architecture
   
     Robust and 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 and security
 
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
10  
 
 
Implementation: SIPpeer 
 
 
   Platform: Unix (Linux), 
   C++
   Modes:
   
     Chord: 
     using SIP for P2P maintenance
     OpenDHT: 
     using external P2P data storage
     
   Scenarios:
   
     P2P 
     client, P2P proxies
     Adaptor 
     for existing phones
     
       Cisco, 
       X-lite, Windows Messenger, SIPc
       
     Server 
     farm
 
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
11  
 
 
Implementation: SIPpeer 
 
 
User interface (buddy list, etc.) 
 
 
SIP 
 
 
ICE 
 
RTP/RTCP 
 
 
Codecs 
 
 
Audio devices 
 
 
DHT (Chord) 
 
 
On startup 
 
Discover 
 
 
User location 
 
 
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
 
 
 
  
 
Dagstuhl 
 Seminar on Autonomic Systems (Jan. 2006)  
 
12  
 
 
SIP 
 p2p summary and open issues 
 
   Advantages
   
     Out-of-box experience
     Robust 
     
       catastrophic failure-unlikely
       
     Inherently 
     scalable
     
       more 
       with more nodes
       
   Status
   
     IETF involvement
     Columbia SIPpeer
 
  
 
   Security issues
   
     Trust, reputation
     malicious node, sybil 
     attack
     SPAM, 
     DDoS
     Privacy, 
     anonymity (?)
     
   Other issues
   
     Lookup 
     latency,proximity
     P2P-SIP 
     vs SIP-using-P2P
     Why should I run as 
     super-node?