[mirrorbrain] 2.6 Release: Network Topological Mirror Selection

From: Peter Poeml <poeml_at_cmdline.net>
Date: Mon, 23 Feb 2009 23:10:58 +0100
This is a long announcement.
Online here [2].

MirrorBrain 2.6 has been released, with a major new feature. Through the
Apache module mod_asn [2], it uses BGP routing data to introduce two
additional mirror selection criteria: network prefix and autonomous
system number (AS). This network-topological knowledge supplements the
country-based mirror selection (which relies on the GeoIP database).
They work on a pretty much lower level and don't replace the latter. The
country lookup is still needed for many requests, because there are many
more ASs than mirrors &mdash; but for a subpopulation of users the
change has a significant impact.

  I owe a big "thank you" to Bjoern Metzdorf who approached me with this
  idea, nearly a year ago. Also, Christian Deckelmann, Simon Leinen and
  Marko Jung have provided very fruitful discussion, insight and

The change has a number of important implications:

- It increases the likelihood to select the fastest mirror for a
  client. (See below.)

- Traffic from clients of, for instance, a large university network can
  be sent to *their* local mirror automatically, with full-featured
  fallback to external mirrors if the internal one doesn't have what's
  requested yet. Such a local mirror is highly likely to be the fastest
  one.  This has the potential to save large amounts of needless traffic
  between organizations.

  Due to the further narrowing on subnet prefix, this works also for
  huge "hypertrophic" autonomous systems like the German AS680 which
  contains the majority of the universities.

- This can be interesting for corporations / organizations which desire
  to run a mirror and have only their clients sent to it. The point is:
  the new criteria can effectively be used not only for mirror
  selection, but also to limit mirror selection to a certain client
  population, based on network topology. The option to set up a
  "private" mirror can spare the organization external traffic.

- And this should be helpful for regions with thin or costly Internet
  bandwidth, enabling them to establish new mirrors. They *can* receive
  normal redirects from MirrorBrain, but have the requests restricted to
  those from clients in the vicinity of the mirror (same network).
  Thus, traffic to clients would primarily be local traffic, and the
  need for outgoing bandwidth would be small compared to what a
  "traditional" public mirror would have to expect.

  This might hopefully lower the bar to find mirrors in many countries.
  Please spread the word!

The change is up and running on download.opensuse.org and also on the
other MirrorBrain instances.

[1] http://mirrorbrain.org/news_items/2.6_network_topological_mirror_selection
[2] http://mirrorbrain.org/news_items/mod_asn_-_Apache_module_to_look_up_routing_data

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Received on Mon Feb 23 2009 - 22:11:00 GMT

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