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* * A bi-monthly electronic news bulletin
* * reporting on the activities of DANTE,
* the company that organises international
* network services for the European
THE WORKS OF D A N T E research community.
No.12, December 1995 Editor: Josefien Bersee
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EMPB/IBDNS TRANSITION SUCCESSFULLY CONCLUDED
On 2 October 1995 the migration to the BT IBDNS (International
Backbone Data Network Service, the Western European part of
EuropaNET) was completed. An operation of this scale - the creation
from scratch of an IP network with nodes in 15 countries - had never
been performed in Europe before and DANTE is pleased to have been
able to bring it to a successful end. The BT team, the colleagues at
the customer networks and the DANTE staff coordinating the migration
worked closely together to make it happen. The EMPB service, provided
by Unisource during the last three years has set a precedent in
offering a high-quality pan-European network service for researchers
and DANTE is keen to maintain such a high standard. The IBDNS network
connects over twenty national networks and research organisations.
For more details on the EuropaNET/IBDNS topology see URL:
http://www.dante.net/europanet.html.
INTERCONTINENTAL CONNECTIVITY: CURRENT STATUS
DANTE currently has 14 Mbps connectivity in place between Europe and
the US. There are five T1's between ANS in New York and Amsterdam
(7.5 Mbps) dedicated for SURFnet. One more T1 to ANS and one E1
(2 Mbps) to ICM are for the usage of the German, Hungarian, Czech and
Romanian networks. Furthermore there are two T1's directly between
ANS and IBDNS. This brings the total capacity for SURFnet to 7.5
Mbps, for DFN, Hungary, Czech Republic and Romania to 3.5 Mbps and
for other DANTE customers to 3 Mbps (with a further T1 on order).
WHEN OPERATING SYSTEMS CAN NOT COPE WITH INTERNET GROWTH....
Recently transatlantic connectivity has been very poor at times for
DANTE's customers. This is partly due to TCP/IP technology
characteristics. The following technical explanation is provided by
Michael Behringer, DANTE's Senior Network Engineer.
With the ongoing growth of the Internet more and more cases occur
where end systems can not reach the destination any longer. The
reason is that in some operating systems the time-to-live parameter
(TTL) of the IP headers is set to a too low value, causing the
datagrams to be discarded on their way to the destination.
Connections to distant hosts thus become impossible.
The Internet Protocol (IP) defines the TTL field for each datagram
sent out. Different implementations of TCP/IP in operating systems
specify different default TTL values. A datagram is sent out with
this default TTL value, where TTL in principle specifies the number
of hops (routers) a datagram is permitted to travel. Each router on
the way to the destination decreases the TTL field in each datagram
by 1. Once the datagram has passed the number of routers specified
initially in the TTL field, it is discarded and thus the destination
cannot be reached.
A number of operating systems specify the TTL value too low to allow
datagrams to travel through the entire Internet. Examples include
Microsoft Windows 95 (TTL 32) and Windows NT (TTL 32), DEC Pathworks
V5 (TTL 30) and HP/UX 9.0x (TTL 30). These values could in principle
be changed, but some operating systems have the parameter hard coded,
which makes this very difficult. According to the TCP/IP
specifications a host should also re-try a connection with a higher
TTL value if datagrams are discarded due to insufficient TTL, but
most operating systems do not deploy this mechanism.
Another problem is that it is not necessarily sufficient to change
the TTL parameters on a local system, because if the destination uses
a lower TTL, the reply packets might not reach the originator due to
the same mechanism. Thus both sides of a pair of communicating
systems need to be changed, making the solution globally very
difficult. For more details and information, a list of TTL default
values of different operating systems, and tools available to fix the
problems see: http://www.switch.ch/switch/docs/ttl_default.html (or
contact M.Behringer@dante.org.uk)
TEN-34: THE FINAL COUNTDOWN
1995 is drawing to a close and as the contract with the EC for the
implementation of the TEN-34 proposal has to be signed this year
DANTE is at the moment doing everything possible to make it happen as
soon as possible. The TEN-34 proposal aims to set up a high speed
pan-European interconnect facility for European researchers. It was
submitted in reaction to the Telematics/ESPRIT Call for Proposals
under the EC Fourth Framework Programme.
Quite a few things happened since the previous 'Works'. With the help
of the EC, France Telecom, BT, Deutsche Telekom (the 'missing' PNO's)
and Telecom Italia (labelled the FUDI group from the initials of
their home countries) agreed to complement the existing TEN-34
proposal with a proposal for a data-transmission sub network based on
ATM Virtual Paths between their four countries offering an aggregate
capacity supporting 34 Mbps access. Unisource, whose previous
proposal covered the whole of Europe - not wholly satisfactory in the
way it covered these four countries though - have now modified it so
that a complementary data transmission service is provided between
the Unisource home countries (Sweden, Netherlands, Switzerland,
Spain) and possibly countries outside the two groups. Unisource and
FUDI have agreed to provide interconnection between their two
networks at at least two points in Europe. The National Research
Networks in the TEN-34 Consortium plan to integrate the two sub
networks at the IP level and to provide an integrated pan-European IP
Service.
In parallel TEN-34 agreed with the JAMES Consortium on the use of the
proposed JAMES facilities as the ATM test network required for
validating ATM based services (the second element of the TEN-34
proposal).
Detailed proposals from the PNO's were provided close to the end of
November, in fact too close for some networks to be able to decide
positively to commit or to complete their own administrative
processes necessary for signing the EC contract. Nevertheless DANTE
submitted a detailed proposal for the Technical Annex of the contract
before the EC's deadline of December 4th. UKERNA (UK), DFN (DE), GARR
(IT) and SWITCH (CH) as well as DANTE as Coordinating Partner are
formally included in the proposal and expect to sign a contract with
the Commission before the end of 1995.
The proposal provides for refinement of the Technical Specification
during the first quarter of 1996. An important part of this work will
be the definition of an objective set of Acceptance criteria which
will ensure that the new service will offer acceptable Quality of
Service and value for money. It will also offer other national
research networks the opportunity to join the project before the
first implementation starts in the second quarter of 1996. The race
is now on to ensure that the formal administrative procedures for
contract signature are completed before the end of the year.
PHARE NETWORKING 1994: PROGRESS AND STAGNATION
As part of the EuropaNET migration the existing link to CESNET, the
Czech national research network which also provides a service to
SANET (Slovakia), is now directly connected to the DANTE PoP in
Amsterdam. A new 2 Mbps link to HUNGARNET was also established, while
a 64 kbps line from the Polytechnic University in Bucharest (Romania)
originally set up as a trial connection to EMPB, was also migrated to
the DANTE PoP as an interim measure until firm decisions are taken on
the long term development of connections from Romania.
Formal contracts for the support of service enhancements to the Czech
Republic, Slovakia and Hungary and new services for Estonia, Latvia,
Lithuania and Poland have been approved by the PHARE Project Office
and signed between DANTE and the National Networks in the respective
countries. As a result a new 64 kbps satellite link now connects
LITNET (Lithuania) to Stockholm while LATNET (Latvia) is able to
benefit from a 128 kbps link provided on a recently installed under-
sea cable between Riga and Stockholm. Investigations on new
connections to Albania and Bulgaria are continuing.
Despite this progress DANTE continues to have difficulty in the
execution of the contract with the EC. Because of differences in
interpretation within the EC on how contract procedures should be
operated and a conservative approach to the justification required to
support cost claims, very little money has been paid by the
Commission to DANTE since the project started over a year ago. In the
meantime the provision of services to end users in the CEE region
depends on the goodwill of suppliers who are prepared to wait for
payment of services they are already providing. Two examples:
Unisource is owed 850 KECU for services provided between January-
September 1995 while PTT Telecom is still waiting to know whether the
EC is prepared to pay at all for the services it provided between
July-December 1994 (a period before DANTE took responsibility for the
project management).
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DANTE - Lockton House - Clarendon Road - Cambridge - CB2 2BH - UK
Telephone +44 1223 302992
Fax +44 1223 303005
E-mail dante@dante.org.uk
WWW server http://www.dante.net/
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