Support for LHCONE

With the successful operation of the LHC accelerator and the start of the data analysis, there has come a re-evaluation of the computing and data models of the experiments. The goal of LHCONE (LHC Open Network Environment) is to ensure better access to the most important datasets by the worldwide HEP (High Energy Physics) community and hence improve the data analysis.

To effect this, several steps have been taken including:

  • flattening the strict Tier1-Tier2-Tier3 hierarchy MONARC model so that any site may connect with any other
  • revisiting the implementation of strategic data placement
  • reinforcing the use of dataset caching – rather like the caching of web pages.

These requirements and concepts are outlined in the Network Requirements document, published in September 2010 by K. Bos and I. Fisk.

Although the operation of the LHCOPN remains the same, moving data between Tier0-Tier1 and Tier1-Tier1, the steps mentioned above have altered the traffic patterns to the extent that substantial data transfers between major sites are regularly being observed on the national and GÉANT IP backbones, often lasting for several days. This traffic is not just a few high bandwidth flows but often made up of many small flows – the users have learnt how to use gridftp very effectively.

These changes have been discussed at the LHCOPN meetings and at a dedicated meeting in January 2011 between the experimenters and the NRENs. Several suggestions were presented and discussed on how to find a way forward. At the LHCOPN meeting in Lyon during February a draft architecture document for LHCONE was constructed, and subsequently revised, taking into account the user requirements and design input from the academic network community.

The main principle was to separate the LHC traffic, thus avoiding degraded performance both to the LHC community and to the other users of the academic IP networks. Doing nothing is not an option as it would almost certainly result in a serious impact on all network users.

Also at the Lyon meeting it was suggested to build a prototype, as documented in “LHCONE prototype planning”. This is to involve a limited number of sites in parallel with deriving a suitable implementation document. The sites important for the prototype are suggested in the document, “A Use Case for the LHC Open Network Environment”.   

LCHONE NREN Meeting 5 April 2011, Paris

The meeting is for the European NRENs to discuss a proposal for how they and GÉANT will create a set of distributed exchange points in Europe based on the GÉANT infrastructure and aggregator networks (or connectors in LHCONE terminology) that best satisfies the requirements of the LHC community.

GN3-11-135v4  Notes of LHC Prototype Meeting in Paris, 5 April 2011

GN3-11-098 LHCONE Draft Agenda for meeting on 5th April at Renater Office

Documents for discussion:
 A Use Case for the LHC Open Network Environment
 LHCONE prototype planning (GN3-11-82v2)
 Draft architecture document for LHCONE  


 Tier 2 and Tier 3 in Czech Republic Now
 LHCONE – Linking Tier 1 & Tier 2 Sites Background and Requirements
 The DE T2 Cloud
 Italian Tier2 prototype
 UK Position on LHCONE
 PIONIER - Connecting Polish T2s to LHCONE
 Presentation of the LHCONE Architecture document
 SURFnet’s LHCONE design considerations

Meeting Logistics
Venue: RENATER Offices
23-25 rue Daviel, 75013 Paris, France
Time: from 10:30 – 16.30 CET



LHC Large Hadron Collider
LHCOPN LHC Optical Private Network
LHCONE LHC Open Network Environment
MONARC LHC Models of Networked Analysis at Regional Centres for
LHC Experiments