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[aprssig] APRS-IS Tier 2 News

Phil - AD6NH ad6nh_lists at dslextreme.com
Tue Jun 3 15:02:10 UTC 2008

Good morning from Tier 2 headquarters in sunny southern California!  I 
would like to take this time to outline some important 
changes/enhancements to the APRS Tier 2 server network.  The network has 
been quietly growing again in the past year.  We now have 44 servers 
online in 19 different countries, and 8 more servers are currently under 
sea trials.  A positive benefit to this growth has been the influx of 
great knowledge from the different sysops that has allowed us to make 
many enhancements to the network as well.

Most recently, there was a thread on the APRS SIG regarding rotate 
addresses [again].  Most of us at Tier 2 are still firm believers that 
if your client software allows you to set one or more server names 
manually, then you should always do that before utilizing a round-robin 
rotate address, but we also recognize that there are software packages 
that do not offer that.  There are also folks who will always want the 
simple answer, and the rotate addresses to offer a simple, if not the 
most effective, connection option.  The down sides of round-robin DNS 
are well documented, even on these lists, so I wont repeat them.  
However, we at Tier 2 recognized early on the desire for regional 
association with operations.  Based on some recent threads, this seems 
to also be true for rotate addresses.  For some time now, 
rotate.aprs2.net has been available as a connection option to Tier 2.  
This address keeps a pool of no more than 22 of the Tier 2 servers (to 
accommodate some router firmware that will not parse more than 22) and 
automatically adjusts for servers that go offline.  It is a fairly 
effective setup, but some clients have responded that they do not 
understand why their UI-View program running in Tuscaloosa is connected 
to the APRS server in Thailand.  While internet routing vs. political 
boundaries is an interesting study, suffice it to say that most clients 
will want to connect to something that makes regional sense.  So for the 
past five months, our sysops have been working on and testing a regional 
rotate address system for Tier 2 that addresses many of these issues.

Based on the packet radio network routing names of several  years past, 
we have broken down the world into five server regions, and have 
assigned servers to those five addresses in those regions.  Again, based 
on the packet radio routing model, we have created the following five 
regional rotate addresses:


Information about which server is in which region, along with a map of 
the five server regions, can be found right on the Tier 2 home page 
www.aprs2.net  There were two debates that ran for a long time in 
developing this scheme.  First, there are often political questions when 
assigning various countries of the world to a region - most notably is 
the question of where Europe and Asia are separated.  I can assure you 
that there was no political or nationalistic malice in choosing where 
servers were placed!  Simple logic was employed.  Secondly, it had been 
requested that we try to adhere to strict internet routing - i.e. have 
the client connect to the server that was closest in IP terms.  
Unfortunately, while that make very good technical sense, there really 
is no way to effectively trace and catalog the routes from each 
potential client to each of the servers.  At any rate, this setup seems 
to be working well, and so it is time to roll it out.  Again, I still 
believe you should be trying to use actual server addresses whenever 
possible, but if you are looking for a regional rotate address that 
makes more sense to you, you now have it!

We always welcome comments and suggestions.  We serve the APRS-IS's 
30,000 plus clients with an average of 1,850 at any given time.  This is 
your network and we are happy to be the maintenance crew for it.  Thanks 
again, and enjoy!

73, on behalf of the Tier 2 team.
Phil Pacier - AD6NH
Tier 2 Network Coordinator

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