Touring ICEBERG -- An Overview and Tutorial Helen J. Wang January 10, 2000.

Touring ICEBERG-- An Overview and Tutorial

Helen J. Wang

http://iceberg.cs.berkeley.edu/

January 10, 2000

Outline

• Design goals

• ICEBERG Architecture

• ICEBERG Signaling System

• Fault Tolerance in ICEBERG

• ICEBERG perspectives on data path creation

• Service Creation

• Security

• Our testbed

• Related Work

• Conclusions and Future Work

Design Goals

• Potentially Any Network Services (PANS): beyond just the two party telephone call service; requires a network/device independent system

• Personal Mobility: person as communication endpoint; requires a single identity for an individual - iUID

• Service Mobility: seamless mobility across different devices in the middle of a service session

• Easy Service Creation and Customization

• Scalability, Availability and Fault Tolerance

• Operation in the Wide Area

• Security, Authentication and Privacy

PSTN GSM PagerAccess Network

Plane

ICEBERG Network

Plane

ISP Plane

A

B

IAP IAP

ISP1 ISP2 ISP3

IAP

SF iPOP

NY iPOP

NY iPOP

SF iPOP PRCA

PACAPCNMSClearing House

ICEBERG Architecture: An Overview

IAP IAP IAP

iPOP on Ninja Base

• Scalability, 24x7 availability, fault tolerance, cost effective -> NOW

• NOW computing platforms mask away cluster management problems: Ninja, AS1

• Ninja: highly available service initiation– Redirector stub

– Good for long running services such as web servers

• AS1: fault tolerant service session– Client heartbeat with session state

– Good for session-based services such as video conferencing

iPOP on Ninja Base, Cont.

• Long running services of ICEBERG: – Name Mapping Service, Preference Registry,

Personal Activity Coordinator, Automatic Path Creation Service

• Session-based service of ICEBERG: -- calls• iPOP on Ninja Base augmented with client stateful

heartbeat support from AS1• iPOP: ICEBERG-capable Ninja Base

ICEBERG Components

• ICEBERG Access Point (IAP): a gateway that interconnects an access network with the ICEBERG network, outside iPOP, has call state machine

• Call Agent (CA): call setup and control• Name Mapping Service: mapping between communication

endpoint and the iUID• Preference Registry: stores user profile including service

subscription, configuration, and customization.• Personal Activity Coordinator (PAC): tracks dynamic info

of a person that is of her interest• Automatic Path Creation Service (APC): establishes and

manipulates data flow

An Illustration

Alice Bob

Carol

IAP

8 9

IAP 1516

iPOP

Call Agent

3

PR NMS

iPOP

Call Agent

5

PR NMS

iPOP

Call Agent

13

1. Call Bob

24

67

10

11

12

14

Outline

• Design goals

• ICEBERG Architecture

• ICEBERG Signaling System

• Fault Tolerance in ICEBERG

• ICEBERG perspective on data path creation

• Service Creation

• Security

• Our testbed

• Related Work

• Conclusions and Future Work

ICEBERG Signaling System

• A signaling system is a collection of network elements (CAs) that speak a signaling protocol to effect call setup, routing, and control.

• Signaling protocol: designed to support a basic call service -- primitives for additional services

• Traditional Basic Call Service: two-party call with homogeneous devices

• ICEBERG Basic Call Service: multi-device call, anyone can invite new member, invitation-based instead of subscription-based call participation

Challenges for Signaling

• Maintain accurate call membership in a highly dynamic call session– centralized approach not scalable and robust

– member list in invitation approach not accurate

• Capture the complete call state– centralized approach not scalable and robust

– must cope with component failure

• Key to a robust wide-area system

Our Approach

• Call session: – group communication over a shared channel among Call

Agents rather than pair-wise communication between CA pairs.

– The channel offers a level of indirection hiding CA identity and location -> tackles dynamic membership

• Call state as Soft State• Shared group channel + soft state

= Light Weight Sessions• Signaling protocol = call session establishment + call

session maintenance and control

Call Session Establishment

• Instantiating Call Agents to form call session. Pairwise communication at this stage

• Key techniques– Idempotent, stateful, keep-alive call request from IAP to

iPOP (AS1 style)

– State machine-aware, but soft state Call Agents

– Call Agents advance call state machines on IAPs through periodic install-state message until receiving new call request with the new state

– Idempotent and soft state inter-iPOP communication

Call Session Maintenance/ Control

• What can happen in an established call session:– user interaction with the device (e.g., hangup, new

invitation, service handoff, put on hold …)– components may fail

• Involves altering/propagating call state (call party identities, devices/status, data path endpoint info, time)

• CAs announce and listen call state to the the shared group channel (group communication in this phase). Receiving new/modified call state at a Call Agent triggers data path creation/modification

Call Session Mtce/Ctl, Cont.iPOP

Call Agent

APC

Call state

iPOP

APC

Call state

iPOP

Call Agent

APC

Call state

Call Session

Call AgentAnnounce

Listen

Announce

Announce

Listen

Listen

IAP

IAP

IAP

Stateful call request

Fault Tolerance in ICEBERG

• An iPOP detects IAP faults: periodic call requests from the IAP. Cannot recover IAP faults.

• An IAP detects network partition from an iPOP: iPOP heartbeats to the IAP

• Call Agents are kept alive by periodic IAP call requests

• Transient component failures or network outage are masked away by soft state refreshes; prolonged failures lead to call drops and cleanup actions

• Ninja Base provides fault detection and recovery for the PR, NMS, PAC, and the APC

Outline

• Design goals

• ICEBERG Architecture

• ICEBERG Signaling System

• Fault Tolerance in ICEBERG

• ICEBERG perspectives on data path creation

• Service Creation

• Security

• Our testbed

• Related Work

• Conclusions and Future Work

A Glimpse of Data Path Creation from the ICEBERG Perspective

• Treating the APC as a black box creates mystery:– What are the appropriate interactions with the

path creation service? – How are the data path maintained robustly

throughout the call session? and how should clients assist this?

– Who owns a path, who gets to create a path, and who gets to destroy? How should this be synchronized

A Glimpse of Data Path Creation from the ICEBERG perspective, Cont.

• The key challenge: fault tolerant wide area path• Centralized APC service, even on a Base, not fit

– cannot stand network partition from that Base– not practical for a world of multiple ISPs

• Distributed APC service pose difficult questions of ownership and access control:– From ICEBERG perspective, synchronized

path creation/manipulation not compatible with the ICEBERG signaling protocol

An Idea on Wide-area Path with the ICEBERG Perspective

• Reduce the difficulty of wide area path by:– one owner per path -> no synchronization– two communicators two paths: output format of

caller path = input format of callee path– need negotiation of caller and callee on the

intermediate data format -- a separate problem from the APC

– iPOP level negotiation sufficient as an iPOP can keep track of the data formats it can support

Outline

• Design goals

• ICEBERG Architecture

• ICEBERG Signaling System

• Fault Tolerance in ICEBERG

• ICEBERG perspective on data path creation

• Service Creation

• Security

• Our testbed

• Related Work

• Conclusions and Future Work

Service Creation in ICEBERG

• Facilitators for service creation in ICEBERG:– ICEBERG signaling protocol primitives– ICEBERG components such as PR, PAC – The APC’s flexible composition of

computation units.

Signaling Primitives Facilitate Service Creation

• Multi-device call operations are building blocks for services:– add a communication endpoint in the middle of a call– remove a communication endpoint in the mid of a call

• Simplify implementation of services that require communication endpoint changes– change an endpoint = remove + add

• Service handoff: generalized call transfer, switch device in a call, achieved by the user inviting another device, then hanging up the first device.

Service Creation, Cont.

• Universal In-box: (more later)– enables the user to receive or retrieve voice

mail, e-mail, phone-calls, fax, instant-messages, etc. in a unified fashion

• Ninja Jukebox service on ICEBERG endpoints• Room Control Service:

– multi-modal control of smart spaces from various devices.

Outline

• Design goals

• ICEBERG Architecture

• ICEBERG Signaling System

• Fault Tolerance in ICEBERG

• ICEBERG perspective on data path creation

• Service Creation

• Security

• Our testbed

• Related Work

• Conclusions and Future Work

Security, Authentication and Privacy

• Assume the existence of PKI– asymmetric crypto to establish shared session

key– symmetric crypto for session security and

privacy• Name Mapping Service:

– public info -> only reply needs authentication

In/outdoorCoverage

In/outdoorCoverageIndoor Coverage

The ICEBERG Testbed

ICEBERG

IAPIAP

IAP

H.323 Gateway

PSTNPSTN

1900 MHz GSM Cellular Base Station

Outdoor Coverage

1800 MHz GSM Cellular Base Station

Data Converter

ControllerPaging BS

Related Work

• Intelligent Network: – separate service logic from call processing; – standardize basic call model (failed); – Problems: inter-operability among switches; integration

with mobile networks, service creation by network operators only

• IETF PINT, WebIN:– IN service logic in the Internet with non-proprietary

languages– service implementation easier, but other problems

remain

Related Work, Cont.

• Hybrid Services– Internet-core approach– “Clouds” interconnected by edge routers

• TOPS: directory service for name mapping, preference, and location tracking

• Mobile People Architecture: person layer, personal proxy as person level router

• H.323: complex, hard to extend, non-scalable, limited in perference support

• SIP: does not address fault tolerance, dynamic call session membership

Conclusion

• ICEBERG: an Internet-core network architecture for integrated communications– Islands of Ninja Bases that offer scalable, available, and

robust services on the Bases

– Signaling protocol: lightweight sessions and soft state approach for scalable and robust wide area call services

– Easy service creation through powerful multi-device call primitives, ICEBERG components, and the APC service

– The Clearing House approach for wide area QoS, scalable resource reservation and integrated billing

Future Work

• Operations, Administrations, and Maintenance• Experiment with more services and generalize a

service creation model• Metrics for a more quantitative evaluation of

ICEBERG architecture• Plan to address the incremental wide area

deployment of ICEBERG architecture