The IN2P3 computer center,
in Lyon France is a
BaBar tier A
remote computing site. This means it will have a copy of all the Babar
data, and will be a major site where Babar computing will be performed.
As such it needs excellent connectivity/performance to
SLAC and other
collaborator sites. The question was therefore posed
by Walter Toki of Colorado State/Babar as to how it is
connected, what the
Internet performance to BaBar looks like, and what are the plans.
The traceroute from SLAC to IN2P3 shows that there is about
60msec. round trip time (RTT) between SLAC and Chicago and then a further
120msec. from Chicago to Lyon, France. It is also seen that the route goes
through CERN. The link from CERN to IN2P3 is 34Mbps. The CERN link to the
US is an STM-1 (155Mbps) link to Chicago. The traceroute
frpm IN2P3 to SLAC when compared with the traceroute from SLAC to
IN2P3 shows the routes are fairly symmetric.
The path characteristics measured from SLAC to
IN2P3 indicate that the bottleneck bandwidth to the IN2P3 site is
about 30Mbps. This bottleneck limit is roughly
bulk throughput measurements between SLAC and IN2P3.
Using the IEPM/PingER
we can investigate the long term performance, in particular the packet loss,
between IN2P3 and various PinGER monitoring sites around the world.
The table below shows the loss seen between several PingER monitoring
sites and IN2P3. Unfortunately there is no Pin gER monitor at
IN2p# so we cannot see how sites look seen from IN2P3.
The numbers in the cells are the percentage loss for the month and
the cells are colored to help indicate the performance. Pink indicates
a very poor to bad performance or > 5% packet loss. Yellow indicates
a poor performance or between 2.5% and 5% packet loss. Green is
an acceptable performance or between 1 and 2.5% packet loss, and no
background indicates a good performance or < 1% packet loss. These loss
thresholds are taken from a
Tutorial on Internet Monitoring & PingER at SLAC.
If we break the performance down into regions then we get the graphs
below, where the results from the monitoring sites are aggregated
by region. The regions are N. America (US and Canada -
14 monitoring sites), Latin America
(Brazil), W. Europe (8 monitoring sites in UK, Denmark, Switzerland,
E. Europe (Hungary), E. Asia (Japan and Korea), Former Soviet Union
(Moscow and Novosibirsk), and the Middle East (Israel). The first graph
uses a linear y scale, and the second a logarithmiv y scale to
better show up
the regions with good connectivity. The log scale graph also shows an
exponential fit to the median of the all the measurements and appears
to indicate that the loss has improved by about a factor of 2 in the last
Gilles Farrache sent email to Les Cottrell November 13, 2000
providing the following planning information for In2P3.
In fact our plans are the following in term of bandwith:
November 2000 : Direct VP ,given by Renater,between ESnet and PHYnet
(30 Mbps average/ 40 Mbps Peak) given by Renater
Between December 2000
and February 2001 : CERN/US upgrade to 155 Mbps. (no use for US as Lyon/CERN
is kept at 34 Mbps)
June 2001 : Lyon/CERN upgrade to 155 Mbps
So in June 2001 we will have several options :
Trafic to SLAC back to Lyon/CERN link and
- Going throught ESnet
- Going throught Abilene
Trafic kept throught VP but we do not know what will be the bandwith.
Olivier Martin of CERN provided the following information by email
on November 29, 2000:
In less than 2 weeks time we should have STM-1 all the way from CERN, the next
step could be to turn the protected SONET/SDH circuit into 2 unprotected
circuits in order to ease experimentation using 4 routers, 2 on each end, one
for production and another one for research with possibly less stable but more
We also plan to issue a market survey for so called transatlantic lambda
service which could be terminated to the new STARTAP (STARLIGHT) but as you
can guess there are a number of issues around all of this.
Page owner: Les Cottrell