DBMS Simulator M. Bucur, R. Cacoveanu and S. CiochinaINC2005, Samos, Greece Dynamic Bandwidth...

DBMS SimulatorM. Bucur, R. Cacoveanu and S. Ciochina

INC2005, Samos, Greece

Dynamic Bandwidth Management System Simulator

M. Bucur, R. Cacoveanu and S. [email protected]

Electronics and Telecommunications Faculty, UPB



Simulator for the Dynamic Bandwidth Management System

in the ATENA project

ATHENA project:– Digital Switchover – Broadband Internet Access for all

Careful planning of the former may help solving the latter issue



ATHENA infrastructure

• Regenerative DVB-T configuration• DVB-T as a virtual backbone, IP over MPEG2

encapsulated data• Broadcasting area is divided into cells, each

connected to a Cell Main Node (CMN)• Fixed wireless links used as uplink from the

CMNs to the Central Broadcasting Point (CBP)



ATHENA infrastructure as presented in ATHENA Technical

Annex



Dynamic Bandwidth Management System

• ATHENA requires a Bandwidth Management System governing the sharing of the IP bandwidth by the CMN connected users

• Traffic stemming from each user suffers continuous variation and also users bandwidth reservations begin and end in time, making necessary the deployment of an Dynamic Bandwidth Management System



Decentralized approach

• Passive and active bandwidth consumers are to be considered, different classes of service are required

• Each traffic flow from each user has to be classified in a certain class of service

• By treating all users’ traffic flows at the CBP issues of scalability and maintenance appear

• A decentralized approach is provided, by managing bandwidth and treating flows at CMN level



DBMS location in the system



DBMS Simulator

• The amount of bandwidth reserved to the users of a CMN is variable in time

• The bandwidth allocated to a certain CMN for treating user reservation requests should be fixed or variable also ?

• The implied answer is variable but the fixed solution could be valid and also easier to implement

• For answering this question a DBMS Simulator has been devised



DBMS Simulator

• In order to choose and validate the DBMS architecture a simulation of the real DBMS has been developed

• The simulated DBMS acts on the same rules as the real DBMS

• The reservation requests from CMN users are simulated by randomly generating one of the following events:

- bandwidth reservation request- bandwidth reservation modification- bandwidth reservation end



DBMS Simulator

• The number of users per CMN can be chosen at the beginning of the simulation

• The number of CMNs, the fixed wireless bandwidth and the available bandwidth at the CBP can also be modified

• In order to maintain intelligibility of the results, only one class of service is defined in the simulation

• The simulation outputs a series of bar-graphs representing the bandwidth levels at different moments in time



• Fixed bandwidth allocation scenario- the bandwidth at the CMN is fixed and no

dynamic management of the CMN bandwidth is made, the total bandwidth being equally shared to each CMN

• Dynamic bandwidth allocation scenario

- the dynamic bandwidth management system is operational and each CMN receives as much bandwidth as it needs at a certain moment

Evaluated scenarios



Fixed bandwidth allocation scenario

• A dynamic bandwidth management module is operational but only at CMN level

• Each CMN has a predefined, fixed, amount of bandwidth that it can use to solve user reservation requests (equal shares to each CMN are used in the simulation)

• User reservation requests are solved locally:- If there is enough bandwidth they are accepted- If all the CMN bandwidth is used, the reservation fails

• Unused bandwidth at one CMN cannot be borrowed by another CMN; bandwidth is wasted



Fixed bandwidth allocation scenario



Dynamic bandwidth allocation scenario

• This was the solution chosen for the DBMS architecture

• The CMNs receive only as much bandwidth as they need; a DBMS module located at the CBP is governing the CMN allocation requests resolution

• Allocation requests are only refused when all the bandwidth available at the CBP is already used; no bandwidth is wasted



Dynamic bandwidth allocation scenario



Conclusions

• The simulation underlined the benefits and limitations of each method of implementing the DBMS:- the fixed allocation solution has the benefit of simplicity

but is far from optimal; it could be used though in the case that the FWA bandwidth is more of a bottleneck than the DVB-T bandwidth dedicated to IP traffic

- the dynamic allocation solution is more complex but can become optimal if certain conditions are met (such as a large enough FWA bandwidth)

• The simulator allowed the validation and optimization of the two level DBMS approach for the ATHENA infrastructure



Acknowledgement

The present paper is supported by the FP6 project ATHENA (Digital

Switchover: Developing infrastructures for broadband access, FP6-507312).

Thank You!

For further insights on this topic you can visit the ATHENA web site: http://www.ist-athena.org

DBMS Simulator M. Bucur, R. Cacoveanu and S. CiochinaINC2005, Samos, Greece Dynamic Bandwidth...

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