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Network Support for Grid Network Support for Grid ComputingComputing

... a new research direction!... a new research direction!

Michael WelzlMichael Welzl

DPS NSG Team DPS NSG Team http://dps.uibk.ac.at/nsgInstitute of Computer ScienceInstitute of Computer ScienceUniversity of InnsbruckUniversity of Innsbruck

AGNM‘05 panel discussionAGNM‘05 panel discussion28 October 200528 October 2005

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Size

ScopeScope

• Grid history: parallel processing at a growing scale– Parallel CPU architectures– Multiprocessor machines– Clusters– (“Massively Distributed“) computers on the Internet

• Traditional goal: processing power– Grid people = parallel people; thus, main goal has not changed

muchReasonable to focus on

this.• (Probably) today‘s most important Grid requirement:

Efficiency + ease of use– Programmer should not worry about the Grid– Ideally, applications should automatically be distributed

(= automatic scheduling, resource brokerage, AAA and many other functions) Autonomic Grid Computing!

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Grid-network peculiaritiesGrid-network peculiarities• Special behavior

– Predictable traffic pattern - this is totally new to the Internet!– Web: users create traffic– FTP download: starts ... ends– Streaming video: either CBR or depends on content! (head movement, ..)

• Could be exploited by congestion control mechanisms– Distinction: Bulk data transfer (e.g. GridFTP) vs. control messages (e.g.

SOAP)– File transfers are often “pushed“ and not “pulled“

• Special requirements– Predictions– Latency bounds, bandwidth guarantees (“advance reservation“) => QoS

• Distributed system, active for a certain duration– Can use distributed overlay network strategies (done in P2P systems!)

• Multicast• P2P paradigm: “do work for others to enhance the total system“

(for your own good) - e.g. transcoding, act as a PEP, ..– Can exploit highly sophisticated network measurements!

• some take a long time, some require a distributed infrastructure

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Some issues: application Some issues: application interface...interface...

• How to specify properties and requirements– Should be simple and flexible - use QoS specification languages?– Should applications be aware of this?

Trade-off between service granularity and transparency!

Traditional method Alternative approach

NSG API

NSG API

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... and peer awareness... and peer awareness

(a) Traditional PEP

Intermediary helperGrid end system Grid end system

Data flow

Grid end system

Intermediary helper

Grid end systemData flow Data flow

(b) Grid PEP

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Problem magnitudeProblem magnitude

• Grid applications show special requirements and properties from a network perspective– and it is reasonable to develop tailored network technology for

them.

• There is another class of such applications...

• Multimedia.

• For multimedia applications, an immense number of network enhancements (even IETF standards) exist.

• For the Grid, there is nothing.

• This is a research gap!

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Problem: How Grid folks see the Problem: How Grid folks see the InternetInternet

• Abstraction - simply use what is available– still: performance = main goal

Wrong.

• Quote from a paper review:“In fact, any solution that requires changing the TCP/IP protocol stack is

practically unapplicable to real-world scenarios, (..).“

• How to change this view: GGF GHPN-RG– documents such as “net issues with grids“, “overview of transport

protocols“– also, some EU projects, workshops, ..

Just like Web Service

community

Absolutely not like Web Service community !

Conflict!

• Existing transport system(TCP/IP + Routing + ..) works well

• QoS makes things better, the Grid needs it!– we now have a chance for that, thanks to IPv6

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A time-to-market issueA time-to-market issue

Research begins

(Real-life)coding begins

Real-life tests

begin

Thesis writing

Result: thesis + running code;tests in collaboration withdifferent research areas

Result: thesis + simulationcode; perhaps early real-lifeprototype (if students did well)

Research begins

(Simulation)coding begins

Thesis writing

Typical Grid project

Typical Network project

Ideal

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Bottom line:Bottom line:

it‘s up to us.it‘s up to us.

Networkers