Best Practices Phase Review Template
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Transcript of Best Practices Phase Review Template
© 2006 Avaya Inc. All rights reserved.
Peer-to-Peer SIP TelephonyChristian Stegh,
N. America Practice Leader,
Emerging Technology and IP Telephony
Peer-to-Peer SIP TelephonyChristian Stegh,
N. America Practice Leader,
Emerging Technology and IP Telephony
VoIP Roundtable
2/14/2007
312-634-2404 one #
2© 2006 Avaya Inc. All rights reserved.
Agenda
Why P2PSIP is hot
Tutorial of basic concepts
Review of open issues
Introducing one-X Quick Edition
DRAFT UNTIL LAUNCH
3© 2006 Avaya Inc. All rights reserved.
Household P2P Names
Napster
BitTorrent
Kazza
Skype
Each is an island unto itself, using proprietary algorithms & signaling protocols.
4© 2006 Avaya Inc. All rights reserved.
Why P2PSIP?
No need for a centralized server– Phones self-organize into a telephony network and connect to
the outside via a simple IP/PSTN gateway or SIP trunk.
Cost savings:– No need for central equipment lowers capital expense
– The operating cost to install & maintain, and add users to the system is also low because no administration is necessary
– Inexpensive calling for consumers across the Internet
Redundancy in telephony architectures
Rapid turn-up time: After plugging the phone into a LAN and entering the user’s name into it, you’re ready to call.
5© 2006 Avaya Inc. All rights reserved.
No need for centralized server
Location information about the called party is kept within the endpoints themselves rather than in a server
Peers know about one another directly or by sharing information with other peers in the network
When a caller doesn’t know the exact location of the party it wants to call, it asks other network peers that are closer to the callee
6© 2006 Avaya Inc. All rights reserved.
P2PSIP
A suite of communication protocols that extend SIP to use peer-to-peer techniques for looking up and reaching users and resources.
vs.
Typical SIPP2PSIP
7© 2006 Avaya Inc. All rights reserved.
Redundancy in telephony architectures
P2P networks allow the work to be distributed evenly across peers
As peers leave — perhaps suddenly due to a crash — work is again redistributed
All nodes are working all the time and as such, standard telephony network infrastructure can become more robust by leveraging P2P
One node can backup another’s voicemail service
8© 2006 Avaya Inc. All rights reserved.
Standards Bodies Support is Swelling
IETF Birds of Feather groups started last year
Group’s size increases at each meeting
Numerous drafts have been submitted to the SIPPING (Session Initiation Protocol Project INvestiGation) workgroup
P2P SIP is not yet an official work item within the IETF, but there is a draft charter
9© 2006 Avaya Inc. All rights reserved.
Tutorial of basic concepts
10© 2006 Avaya Inc. All rights reserved.
Basics
P2P layer = distributed database
In Real Time Communications, data items stored are mostly information about a user
– Name
– IP address of phone
– Etc.
Requirements for a P2P layer for Real-Time Communication (RTC) are not the same as the requirements for file sharing
11© 2006 Avaya Inc. All rights reserved.
P2P Layer
The P2P layer is effectively a replacement for the registration, location, and lookup steps of a SIP server
It handles three things:
– How to register a phone or a user with the P2P overlay network (when the phone or user joins the network)
– How to lookup a phone or a user in the P2P overlay network (when a call to the phone or user is made
– How to dynamically shift information when peers join and leave, so that the load is balanced across peers and so the sudden loss of one or more peers doesn’t cause the network to lose track of its current registrants
12© 2006 Avaya Inc. All rights reserved.
Finding Peers
At the heart of the P2P algorithm is an efficient way to search for and retrieve information about the location of peers in the overlay network.
In small networks, all peers know each other
In large networks, too much memory would be required
– Distributed Hash Tables are the answer
13© 2006 Avaya Inc. All rights reserved.
Distributed Hash Tables
A DHT is a structured way of organizing the P2P network so that every peer only knows about some of the peers in the network.
More efficient than knowing about all peers,
A peer can quickly find out about another by asking other network users.
When a user tries to call a peer that is not in its table, it queries other peers, which quickly return the location to the user.
14© 2006 Avaya Inc. All rights reserved.
Popular DHTs include
Pastry
Tapestry
Chord - the basis for some early P2P SIP work
Since there are already many methods and more emerging, DHTs will likely take some time to standardize.
15© 2006 Avaya Inc. All rights reserved.
ChordUses a ring structure for the nodes in the overlay
Each node is assigned a unique ID and keeps a database of IDs of some of the nodes in the network
When a user searches for a node that is not in its own table, the node nearest to the destination address is contacted
The nearby node either returns the location of the callee or it sends the request to a node closer to the destination
Efficiently minimizes lookup table sizes
16© 2006 Avaya Inc. All rights reserved.
Routed queries like Chord
N4
Publisher
ClientN6
N9
N7
N8N3
N2
N1
Lookup(“title”)
Key=“title”Value=MP3 data…
Without more advanced algorithms, # of hops would be linear to # of peers
17© 2006 Avaya Inc. All rights reserved.
The Chord algorithm –Scalable node localization
Each node maintains
– Finger table
• Entry i in the finger table of n is the first node that succeeds or equals n + 2i
– Predecessor node
Search in finger table for the node that most immediatley precedes id
Invoke find_successor from that node
– Guarantees that a file is found in O(log(N)) steps
18© 2006 Avaya Inc. All rights reserved.
Standards Debate
DHT algorithms continue to be refined
But a bigger philosophical difference among early works needs resolution:
– Should the P2P protocol be integrated into SIP by adding new headers?
Or
– Should it be a separate and distinct layer?
19© 2006 Avaya Inc. All rights reserved.
P2PSIP vs. File-sharing
P2P layer for RTC P2P layer for File-sharing
# of data items # of nodes Can be >> # of nodes
Size of data items Small Can be large
Lookups Infrequent -- not a significant portion of a phone’s workload
Can be frequent
Join/Leave frequency Low (especially wireline)
Can be high
20© 2006 Avaya Inc. All rights reserved.
Enterprise vs. Consumer
See (at least) two distinct applications of P2P-SIP
Consumer telephony: Skype-like
Enterprise telephony: PBX systems for enterprises
These two applications have different requirements
21© 2006 Avaya Inc. All rights reserved.
Enterprise vs. Consumer
Enterprise Consumer
Hierarchy Natural groups (office, division, etc) that a P2P layer should respect.
Artificial?
Trust Model -- Authentication (“Can this phone/group join the network?”) is very important.-- Preventing rogue behavior not so important.
-- Authentication is not so important-- Preventing rogue behavior is important.
Scale 10,000 peers is a large network 10,000 peers is a small network
22© 2006 Avaya Inc. All rights reserved.
Merging non-P2P clients into the Model
SIPUAA
UAPeer
E
UAPeer
DProxyPeer
P
RedirPeer
R
PeerQ
GatewayPeer
G
UAPeer
F
NAT
NATUA
ClientC
P2PSIP Overlay with peers speaking Peer protocol
P2PSIPClient Protocol
23© 2006 Avaya Inc. All rights reserved.
Sample Message Flow
Client calling a Peer:1) Client C sends a query to Peer Q for the location of User U.2) Messages are exchanged between peers, and User U is
determined to reside on Peer F3) Peer Q sends response back to Client C.4) Client C sends SIP Invite message to Peer F.
UAPeer
E
UAPeer
DProxyPeer
P
RedirPeer
R
PeerQ
GatewayPeer
G
UAPeer
F
NAT
NATUA
ClientC
P2PSIP Overlay with peers speaking Peer protocol
P2PSIP Client Protocol
SIP Invite
24© 2006 Avaya Inc. All rights reserved.
Some Design Questions
Peer vs Client Protocol: Are these the same things, or not? Do we really need a Client protocol? Are either SIP?
How to find a media relay? Does it have to be network-path optimal?
How best to arrange NAT traversal?
Security: If peers are untrusted, how do we protect sensitive messages flowing through them?
Credentials. Certs from a CA? Self-signed?
Bootstrapping. How to start from zero?
25© 2006 Avaya Inc. All rights reserved.
Small Office Challenges
Very Small Business
Answer: Quick Edition 2.0
Very Small Business
No local tech support, limited technical knowledge
Need solutions that can easily grow with the business
Communications must be completely reliable and secure
Costly moves, adds and changes
More home and remote workers
Branches
No local tech support, limited technical knowledge
Managing branches is a real headache
–Different systems / vendors
–Ability to manage
–Communications must be completely reliable and secure
Costly moves, adds and changes
More home and remote workers
26© 2006 Avaya Inc. All rights reserved.
Avaya one-X™ Quick Edition Release 2.0 Intelligent Communications for the Smallest Office
IP Telephony for Small offices
– SIP-based peer-to-peer technology, no centralized hardware
– Voicemail, auto-attendant, call processing etc – all in the phone
Dramatically simple, cost effective, productive
– Default install in minutes, customize as required
Release 2.0 delivers– SIP Trunking, Multisite
Provisioning Tool, QOS, Call Park, Page and Retrieve, Teleworker
28© 2006 Avaya Inc. All rights reserved.
Avaya one-X Quick Edition Release 2.0 P2PSIP Attributes
Simple – Set up and make calls in minutes, customize as required
– Server-less configuration reduces acquisition costs, TCO
Cost effective– Reduce number of trunk lines
– Commonly used features built into the phone
– Centralized management reduces maintenance costs
Connected– Designed for Branches, or Very Small Business
– Enterprise wide dial plans drive efficiency
– Leverage internet infrastructure while maintaining voice quality
29© 2006 Avaya Inc. All rights reserved. 29© 2006 Avaya Inc. All rights reserved. Avaya Proprietary. Not For Distribution. Use pursuant to Company instructions.
Peer-to-peer discovery, setup
WAN
LAN
Standalone Configuration
Multisite Provisioning
Tool
Teleworker
HTTPS
P2P/SIP
Quick Edition Branch
SIP Service Provider
G10Gateways
PSTN
30© 2006 Avaya Inc. All rights reserved.
WAN
30© 2006 Avaya Inc. All rights reserved. Avaya Proprietary. Not For Distribution. Use pursuant to Company instructions.
PSTN
Peer-to-peer discovery, setup
WAN
LAN
Branch Configuration
Multisite Provisioning
Tool
ConvergedCommunication
Server,SIP Enablement
Services
CommunicationManager
SIP
Teleworker
HTTPS
SIP
P2P/SIP
G10
Gateways
HQ
Branch
Quick Edition Branch
31© 2006 Avaya Inc. All rights reserved.
Quick Edition Teleworker
WAN
InternetVPN
VPN
Teleworker
Teleworker
Ext 202
Ext 200Ext 201
Ext 204 Ext 203
Ext 202
Ext 201 Ext 200
Ext 203Ext 204
1. The Quick Edition teleworker feature provides Quick Edition functionality to remote workers of local Quick Edition sites
Teleworker over Internet (VPN)
Teleworker over WAN
2. Teleworker is a mode of operation in the 4610 and 4621 phones which allows Quick Edition to have presence as part the local site dial plan via a VPN or WAN connection
3. VPN connectivity over the Internet is provided by VPN routers which provide for secure LAN access to the branch
5. The VPN router is only required to route IP unicast traffic to/from the LAN and remote connection
4. Teleworker mode removes the dependency of IP multicast traffic which is required for operation on the local LAN
8. This same VPN router can be used to provide data connectivity for a PC to the local network if desirable
6. The teleworker phone can then be moved to/from the remote location and the local branch with the retention of all settings, voicemail, with backup while in transition
7. Standard call forwarding rules can also be applied to direct calls from an internal office phone for off-hours or virtual office day transparency
32© 2006 Avaya Inc. All rights reserved.
Features
PBX system for small-med organization
Is P2P; no central component.
– Phones cooperate to produce PBX functionality
Supports many standard PBX features:
– Call forward, call transfer, conference call, etc.
– Corporate directory (built automatically)
– Even features like voicemail, auto attendant, call logs, etc. are done in a distributed fashion.
– See www.nimcatnetworks.com for list of features
33© 2006 Avaya Inc. All rights reserved.
Features (cont.)
Designed for resiliency - system still works if some phones become unavailable.
Designed to be very “plug-and-play”
– For basic operation, the only configuration required is to enter your name on your phone.
Two ways to connect to outside world
– Through an optional PSTN gateway box (TTI)
– Though a SIP service provider
34© 2006 Avaya Inc. All rights reserved.
Implementation
Uses SIP for signaling
Uses a simple proprietary P2P layer
– Uses multicast to locate peers and join overlay
– Uses both multicast and unicast to distribute info about each phone
– Each phone has complete knowledge of other phones
Uses various proprietary schemes for distributing services in the P2P environment
35© 2006 Avaya Inc. All rights reserved.
More information
http://www.p2psip.org/
http://www.cs.rutgers.edu/~rmartin/teaching/fall04/cs552/lectures/p2p.ppt
http://www.mpi-inf.mpg.de/departments/d5/teaching/ws03_04/p2p-data/11-18-paper1.ppt
www.avaya.com/quickedition