InfoMagic Standards 1993 July/Disc.iso/inet/isoc/isocnews/issue1_3/015.201

Text File | 1993-02-08 | 10.2 KB | 188 lines

N-1-3-015.20.1, Australia by Geoff Huston*, <[e-mail]>


This article examines the structures employed within Australia to
manage the national connection to the Internet.  The Australian
Academic and Research Network (AARNet) is connected to the Internet
via a satellite link which connects into the U.S. Federal Agency
Internet infrastructure.  Since the original 64Kbps link was installed
in July 1989 the link capacity has been upgraded in response to acute
congestion three times - to 128Kbps in November 1990, to 256Kbps in
May 1991 and 512Kbps in February 1992.

The response to this increasing traffic profile has been the adoption
of a number of measures within the Australian network intended to
localise as much of this traffic as possible.  The actions adopted by
AARNet in this area may be useful pointers to other sectors of the
Internet in a similar position of having Internet connectivity
implemented via a long skinny pipe.

The first of these areas is configuration of the DNS within AARNet.  To
assist in reducing the DNS traffic levels across the link, a system has
been installed to act as a national DNS as a network supported
resource.  This caching forwarder is configured into all relevant DNS
configurations within AARNet, with the intention of localising DNS
queries into a large cache.  A fake root nameserver is also configured
onto this system, so that the DNS domain will not fatally collapse in
the event of extended outages of the single international link.  DNS
traffic on the link has been reduced from 10% to some 4% of total
traffic levels, largely as a result of the deployment of this
forwarder.

The second area is that of management of the usenet news flow.  With
current news volumes now reaching some 30 Mbytes per day, it is not
reasonable to support a number of concurrent news streams across a
single physical link.  A single comprehensive news flow is fed to a
single Australian site, which is redistributed to regional
redistribution points along logical links which correspond to the
physical infrastructure of the network.  Using low delay NNTP sessions
and a dedicated NNTP flow director, news reaches all Australian AARNet
sites generally within some 15 minutes after reaching the major U.S.
usenet backbone sites.  The benefits of such structuring are not only
the rationalisation of the use of the international link, but also
improved performance of the service to the user population.

The third area is that of file transfer using the FTP (File Transfer
Protocol) utility.  If file transfer was a small contributor to the
total volume of traffic on this link, then provision of adequate
international communications capabilities would not be a major
engineering issue.  However, in examining the current traffic profile
across this international link the major component of incoming traffic
is associated with the FTP application - some 65% of the bytes
transferred every month (some 23 Gigabytes in February 1992) is FTP
traffic.  This traffic has been growing at a much faster rate than any
of the other network applications.  Engineering solutions for such
explosive growth is difficult, partly due to the problems in
estimating the extent and duration of the growth, and partly due to
planning for adequate resource provision to support the potential
demand.

The response by AARNet has been to install a single major archive
server at the major hub of the Australian network to service the
information retrieval requirements of the AARNet community.  The goals
of the exercise are to reduce the volume of duplicate file transfer
requests to international locations, and to improve the on-line
information services currently available within AARNet.

There are several specific issues that are addressed by this archive
service:

   a) Location of Information Resources.  Users may be aware that some
      information they require, be it data, programs or documents, is
      on-line but do not know the name and/or network address of the
      computer system(s) upon which it is located - a typical approach
      is to adopt a scattergun method in attempting to locate the
      resource within the major archive sites.

      In many cases, copies of offshore information resources are
      maintained within Australia, but users are unaware of them and
      continue to transfer data from sites in the USA, Europe and the
      rest of the world.  This problem is further complicated by the
      fact that local (Australian) copies of information resources
      are sometimes out of date, and similarly difficult to locate;

   b) Poor Directory Tools.  The existing tools for addressing the
      identification and location problems are crude, unwieldy and
      inefficient.  Users are therefore not prepared to spend the
      time and effort to find the "closest" or "most network
      efficient" location of information;

   c) Announcements.  New versions of software, technical reports,
      new data sets, etc., are frequently announced to the network
      user community via electronic mailing lists and network news
      bulletins.  These postings generally only cite the original
      source location of the item, and therefore generate a rush of
      identical requests to the same, usually international
      location, from the users that read them.  Ideally, one copy
      should be brought to Australia and then made available to the
      rest of AARNet community nationally;

   d) Poor Access Tools.  The standard method of information transfer
      is based on FTP and the "anonymous" user concept.  FTP itself,
      and the "anonymous" guest account mechanism, are not ideal end
      user interfaces for the distribution of information.  They are
      however, widely supported and available on all hardware and
      software platforms;

   e) Poor Performance.  Because some sources of on-line information
      are poorly connected to the network, or very remote from
      Australia (e.g., Finland), and/or are hosted on systems that
      are not dedicated to providing on-line information (i.e., are
      general purpose computing systems) some users are discouraged
      from making use of the information services available to them
      by the poor performance of the transfer, and the typical
      response is to abort a slow transfer session and retry, adding
      to the overall traffic volumes due to successive retransmissions.

AARNet has installed a 5 Gigabyte fileserver within the network to
address these issues.  This system supports a number of functions
including the mirroring of major Internet archive sites in order to
provide a high performance local resource with authoritative copies of
the original data source, an Archie service (by arrangement with
McGill University) to enable named searches on both the local archive
and also the larger Internet-wide Archie database, the Prospero
filesystem, in order to provide transparent access to FTP servers not
mirrored locally, and a number of Wide Area Information Server (WAIS)
databases.  Further activity within the broad area of distributed wide
area filesystems (such as AFS and Alex) is anticipated to lead to this
archive service publishing its resources by other methods as well as
the current FTP, Archie and finger access methods.

As well as providing a positive impact on the growth trends of FTP
traffic across the international link, it is noted that there are also
significant service roles being performed by this archive service.
These include the provision of a single major authoritative source for
Internet resources for Australian users, improved performance in
resource access, and consistency of the access mechanisms.

While such a service could in theory be provided by any member of the
network, there is no obligation on the part of individual AARNet
members to continue to provide the archive services they currently
support, or to archive information of interest to the AARNet community
at large as a production service.  It must be recognised that such
typically peer service/client relationships, while very useful in
establishing the feasibility and potential demand for service within a
short timeframe, can run into viability problems when the level of
demand swamps the level of volunteer support.  Given the important
roles that the AARNet archive server undertakes, it is supported
within a production role, as part of the network infrastructure.

When compared to the high recurrent costs in supporting the link from
Australia to the United States, the relatively small costs of
establishing and maintaining this service are seen as a highly
leveraged investment in providing high performance access to Internet
resources for the Australian community.

The system is now online to the Internet as "archie.au".

The final area is that of management of mailing lists.  Here users are
gently encouraged to subscribe to the most popular Internet mailers
via subscribing to local exploders maintained within the country.  At
this point there has been only minor activity in attempting to provide
a robust and general mechanism for supporting automated local mail
list exploders.  With total mail volumes currently being recorded at a
level of some 8% of total traffic levels there does not appear to be
an adequate rationale for attempted reduction of mail traffic levels
through attempting to reduce the number of duplicate incoming mailing
list postings as yet.

In summary, it is noted that the engineering requirements of
interacting with the Internet are somewhat different when a highly
active network is located at the far end of a long skinny pipe, as
distinct from being located within a rich mesh.  As new applications
are deployed across the Internet, there is a continuing commitment
from the Australian network provider, AARNet, to examine the
feasibility of engineering local redistribution mechanisms which can
improve both the cost-effectiveness of the international link itself
and improve the levels of performance of the services accessed by the
local user population.  In this way the AARNet, as a network provider,
is not just undertaking the role of provision of connectivity and
bandwidth, but investing resources in an active role in enhancing the
quality, reliability, and performance of the services provided to
users.


*Manager, Australian Academic and Research Network