[Xastir] Multiple Servers

[Robbie, wa9inf]

Dan Brown wrote:

>On Wed, 25 Oct 2006, Ray Wells wrote:
>
>  
>
>>Gerry Creager wrote:
>>
>>    
>>
>>>But do you *need* to connect to each of the servers?  Connecting to 
>>>the Core at one point, and using a rotate scheme, should accomplish 
>>>what you would want, the ability to fail over another server when, 
>>>albeit rarely, we have a server die.
>>>
>>>Multiple connections to multiple servers tends to lead to loops on the 
>>>servers.  AE5PL's done a lot of work to stop that and the Core sysops 
>>>have periodically gone thru and individually asked folks to help us 
>>>stamp out redundant connections.
>>>
>>>gerry
>>>
>>>      
>>>
>>Hi Jerry,
>>
>>No, I don't need to connect to each server at the same time. All I'm 
>>looking for is a redundancy scheme whereby if one server falls over, 
>>Xastir will attempt to connect to an alternative server in a manner 
>>similar to UIView.
>>
>>Server failures are rare but, in accordance with Murphy's Law they will 
>>happen when I'm not here, which is quite often, and I want to cover that 
>>possibility.
>>    
>>
>
>I believe that this has been somewhat implemented by the APRS IS guys using
>round robin DNS records with a 60 second (or so) ttl for "rotate.aprs.net"
>
>Using "dig" on a command line: 
>
>------------------------------------------------------
>
>Myhost.foo$ dig rotate.aprs.net
>
>; <<>> DiG 9.2.1 <<>> rotate.aprs.net
>;; global options:  printcmd
>;; Got answer:
>;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6864
>;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 2, ADDITIONAL: 2
>
>;; QUESTION SECTION:
>;rotate.aprs.net.               IN      A
>
>;; ANSWER SECTION:
>rotate.aprs.net.        46      IN      A       165.91.140.28
>rotate.aprs.net.        46      IN      A       64.58.200.20
>rotate.aprs.net.        46      IN      A       134.173.254.38
>
>;; AUTHORITY SECTION:
>aprs.net.               5986    IN      NS      ns3.aprs.net.
>aprs.net.               5986    IN      NS      ns7.aprs.net.
>
>;; ADDITIONAL SECTION:
>ns3.aprs.net.           5986    IN      A       24.123.66.139
>ns7.aprs.net.           5986    IN      A       64.58.207.2
>
>;; Query time: 47 msec
>;; SERVER: 192.168.1.7#53(192.168.1.7)
>;; WHEN: Tue Oct 24 19:56:43 2006
>;; MSG SIZE  rcvd: 149
>
>------------------------------------------------------
>
>
>
>If you use dig a few times in a row, you'll see the 3 lines in the "Answer
>section" change order, and the TTL (46 here) will decrease over time.  I've
>not looked at the Xastir code, but, As long as users use hostnames and
>xastir (and other stuff like nscd) doesn't cache the Hostname->Ip mapping
>any longer than specified, you should be able fail over by using
>"rotate.aprs.net" within 60 seconds, plus or minus timeouts to see if things
>are truely down. 
>
>Still, it would be nice functionality to have -- use one "interface"
>specification and have multiple possible hostnames to connect to.  I
>personally just have multiple interface specifications.  If one goes down,
>I can start another manually, fairly easily. 
>
>  
>
I am new to xastir myself, and yes, UI-View and WinAPRS and others use 
"one" server, which does all that if I understand what is being 
attempted there..

Just set xastir up to connect to rotate.aprs2.net port 14580 and supply 
a filter like m/50 for 50 km from your position. When one server that 
you might be connected to drops out, within a few second you will be 
connected to another one without any intervention by you.. Since a few 
days ago only, I have used rotate.aprs2.net. Not long enough to tell 
about dropping from a server. My UI-View station drops only when I get a 
clitch in my router, or I kill the program for one reason or another.

That being said, did I miss something here? Were you discussing 
something different... :-)  Sorry if I didn't get it...

Robbie