Content Delivery Infrastructures for Live Streaming progress report

Content Delivery Infrastructures for Live Streaming Progress Report

held at the TF-VVC Face 2 Face meeting of 18 May 2006, Catania

Outline

OpenCDN is an application-level Content Delivery Network for replication and splitting of live multimedia content, based on the deployment of a Streaming Relay Overlay Network. It has grown as an OpenSource project, and can be adapted to different kinds of streaming technology. Participation can be in the form of development and testing, set up of remote replication nodes, and contribution of live feeds.

Architecture

OpenCDN is made of the following entities:

a Request Routing and Distribution Manager (RRDM) performing a centralized control
some replication Nodes
some content Origins
an Announcement Portal where viewers can browse a list of contents provided by the Origins, and retrieve the Surrogate Node which is nearest to the client

Features

New replication nodes and contributing sources may be independently added, without the need of inter-administrator coordination

Resilience to network partitions, node failures, and RRDM reboot

Viewers don't need a special application: a browser and a movie player are enough

Different streaming technologies (Real, QuickTime, WM) can co-exit

Distribution root is located near the encoder

The edge server is located near the requesting client

These two year achievements

adaptation to the Helix server by Real

Windows Media can be delivered through Helix

authentication infrastructure

inter-entity authentication

edge surrogate <-> client RTSP authentication

UDP probes optimization

use of single-thread asynchronous I/O instead of the forking of many sub-processes

a convergence layer allows for co-existence of different streaming technologies within the same host

presence of Origin entities allow

independent registration of the available contents metadata
determination of the FirstHop Node which is nearest to the Origin

first mile (near to the Origin) and last mile links are traversed only once by media streams

determination of the LastHop node which is nearest to the client

it was proposed by Cineca and there called PYTE
is based on an objective latency measure, i.e. the RTT in between the viewer and candidate edge nodes
global LastHop nodes can now be deployed

Things to do next

a content provider kit offering a simple web interface, and based on VLC

an adaptation layer for Windows Media Server (an open source project encourage interested parties to develop code by their own)

documentation (now in the form of sparse README files, should be unified)

aging of state information

policy for a public use by (independent) content providers and supporting nodes

a network topology aware deployment of the distribution tree

many refinements

a better announcement portal layout
embedding of the viewer
configuration GUI
graphic sketch of the resulting topology