P2P (Point to Point)

Online video has emerged as the most badwidth hungry application.Some researches have state that video services ocupy 60% of P2P traffic,which each file averaging around 1GB.
Hence VOD and downloads use huge amounts of network bandwidth and this is exerbated if a video is particularly popular.A singel video report covering 9.11,for instance, had a click rate exceeding 100 million

P2P connects peoples in a network and users can communicate directly via the internet rather than though any intermediary.Its application enable users to directly exchange and share file instead of connecting to servers for file browses and downloads..Significanly P2P alters the reality that the internet is the dominant power core as P2P devolves power to users via decentralization, while greatly enhancing the value of online services

However,the wide range of P2P appplicaitons on the internet describes a trend for which it is complicated for carriers to strategize.Its advantages are fairly evident.Firstly,P2P creates new opportunities as it can attract more users to broadband networks that provide these applications.Secodnly,P2P technologies can be used to optimize existing services and networks to increases perfomance and decrease cost.P2P and online TV for example represent a good combination.

Based on existing services, carriers can explore new P2P operation and profit models to render these application managable and profitable, and allows them to develop in a constructive,sustaibale way that caters to user requirements

The most obviously negative aspect is that if P2P applications are all interconnected in parralel, network bandwidth increase tremendously.In extreme cases, this may result in network congestion and the perfomance degradation of other internet application.Moreover, P2P based voice communicaiton technologies such as Skype have direclly threatened carrier's traditional voice communicaiton services

Given these considerations,carriers are left with two broad strategies:Prevent the use of P2P or develop and guide sustainable usage.Since P2P represents an irreversible trend,logic dictates that usage guidance is the better long term option,despite the fact that the challenges currently outweigh the opportunities.Correct decision making and implementation will be the tool to heighten the potential benefits

Many carrier have in fact started developing solutions for P2P apllication.Carriers should prevent illegal network resource usage,while exploting P2P applications' inherent advantages and transform then into something useful

Three strategies can be followed to reach this goal.The first is to limit overall bandwidth.Traffic should be localized to reduce pressure on the backbone network.The second is to employ P2P technologies to reconstruct existing networks,thereby increasing perfomance and reducing cost.Thirdly,P2P technologies can be used as a platform to develop new services and increase income.Some carriers have already started expanding network bandwidth


Adjust MAN architecture


Both P2P software download such as Bit Torrent, and live broadcast P2P software including PPLive are executed via applicaiton layer duplcations between node.In the present MAN architecture,users exist in a dual layer separation mode in the acces network.

Application layer duplication between users can only occur through the core convergence layer of the MAN or the backbone network and the bandwidht consumed on the MAN core convergence is proprotionate to the numbers of users

The present MAN see data traffic passing the convergence swtiches and BRAS before arriving at the MAN egress.No fixed bandwidth is reserved for each users from the access layer to the MAN egress and whenever a large amount of traffic exists on the access layer,much bandwidth will occupied on the convergence layer or the backbone network.Moreover ADSL bandwidth in the access network is asymmetrical as uplink bandwidth is fast less than downlink bandwidth.If application layer duplications are implemented,uplink bandwidth demands are increased,which would exeed present access network capacities.

If P2P services become mainstream services over present network architecture,badwidth on the MAN core convergence netwrok will see the greatest bottleneck,while access layer bandwidth will be continously occupied.In terms of online TV applications, P2P duplications on the application layer are not cost effective in term of bandwidth usaged compared with multicast.Network access can only adjust MAN architecture so that it can adapt to the P2P application layer duplication model and reduce pressure on the MAN convergence layer's P2P derived bandwidth demands.

To make the MAN architecture suitable for P2P applications layer duplications, the following principles should be obsreved:

1. Selecting symmetrycal access equipment

DSLAM is continously used by carriers but possesses asymmetrical access equipment that cause significanly more downlink abdwidth than uplink. It is rather suitable for C/S model than P2P.Therefore a shift toward symmetrical access technologies such as LAN,ADSL2+ or EPON is recommended

2. Flattering the access network

The nature P2P traffic means that placing the layer 3 gateway closer to users will increase bandidth saving on the MAN core convergence layer

3. Building a full meshed structure at the core convergence layer

MAN currently adopts a dual start,tree structure.All traffic passing MAN must cross two routers at he MAN core.This is unsuitable for P2P traffic,adaptation to which necessitates the adoption of multi node architecture at the MAN core layer under which different nodes network via the full meshed