[aprssig] Tier 2 Status

Steve Dimse steve at dimse.com
Wed Jun 21 21:29:19 CDT 2006

On Jun 21, 2006, at 9:55 PM, AE5PL Lists wrote:

> ???  If all the core servers go down, there is still some level of
> connectivity which would not exist at all if everyone connected to the
> core servers.  You are objecting to people have some level of
> connectivity over none?

Not at all. I object to users having no notification that there is a  
major problem in the network, of having extremely limited  
connectivity and receiving no notice. Of course, this is very  
hypothetical, even with three servers the core has never gone  
completely down, the more servers you add the less likely this becomes.
>> For example, say a typical tier 2 server has some sort of
>> problem with its connection to tier 1. As a user, you are
>> connected to a network, but have no idea your APRS universe
>> is limited to those people connected to the same server. On
> Ok, and just what kind of permanent connection problem to Tier 1 where
> the connections to the Tier 2 server would not also be lost would be
> circumvented by connecting directly to the Tier 1 servers?  None  
> (or an
> infinitesimally small probability).

First exactly where did I say anything about permanent? I am talking  
about transient problems. There are many times when tracking down a  
problem with findU, where I have been able to reach one of the findU  
servers but not the other, but when I ssh into the one I can reach, I  
find that from there I can reach the other server. The internet is  
far from the perfect self-healing network it was originally designed  
to be.

>> With core connections for the two clients, the odds are 33.3%
>> one hop and 66.7% two hops.
> These are meaningless statistics.  You are using an incorrect
> supposition that the Internet is a monolithic entity and that the
> weakest link is the APRS-IS server!  Do a trace route sometime and see
> how many single points of failure your connection goes through.  Your
> numbers are nonsensical.

Actually, if you want to consider the routers that are on every hop,  
my numbers become even more impressive! Say the average path between  
IPs goes through 10 routers (if you don't like that number, give me  
another and I'll run that). On average, a path between two stations  
connected to the core goes through 26.6 routers. The path between two  
tier 2 servers goes through an average of 35.8!

> Hate to burst your bubble Steve since you have been out of the
> operational side of APRS-IS for years now, but adding two more core
> servers doesn't accomplish anything other than _minimally_  
> spreading the
> core load out to two more servers.  When ever a fourth server was  
> added,
> it received a fraction of the load found on the other servers.

That is true, because it never became reliable enough to have  
received the publicity to move people over. The load it did receive  
was those people using rotate.aprs.net. What is your point here?

> And I am
> sorry, but the core sysops are providing superb capacity for _free_.
> Fat pipes are only one issue.  Seems to me that you shut down the
> www.aprs.net server because too many people were using it.

The first APRS IS hub was on a T-1 line at the Miami Museum of  
Science. You are right, I shut that down years ago because it could  
not handle the load, and I couldn't exactly go to them and ask them  
to put in a fatter pipe, could I? There were others that had access  
to better pipes, and the system was better off having the hubs moved  

> You sure are
> liberal in offering up other peoples' facilities and criticizing them
> when they don't meet your ill-informed expectations.

Ummm, I sure don't see anything I said that is critical of the core  
(or the tier 2) sysops. Someone expressed surprise at the way the  
system is implemented now. I answered with the original design (which  
I consider more efficient) to balance the opinions of those who think  
a second tier is better.

> Instead of fighting second tier servers which aren't going away and
> which are providing a very quality service to the APRS community, why
> don't you spend your time on something productive like continuing to
> improve findU which you do very well.

I think you misunderstand my intention here. I am not fighting  
against tier two servers, simply explaining the current situation in  
response to Stan's question. You are right that I am out of the APRS- 
IS by choice, but that does not mean I do not have an understanding  
of the issues involved. The fact is the APRS IS works very well, in  
large part due to your work.

Steve K4HG

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