Possible solution to determine if default network has changed (MacOS only for now)

Bob Sneidar bobsneidar at iotecdigital.com
Wed Oct 23 11:10:23 EDT 2019


Yeah, I won't be able to accomodate load balancing and failover, but the vast majority of situations where the network has changed and LC and sqlYoga doesn't know about it should be taken care of. 

Essentially my strategy is to save the node and router MAC addresses in a property of the database utilities behavior button I use, then check it each time I attempt to open a connection to the SQL database. This in addition to checking the availability of the SQL database by telnetting to it with the SQL port used. 

All this to preclude the issue where attempting to connect to a non-responsive SQL server ends up causing a 1 minute delay because apparently that's the timeout. 

Bob S


> On Oct 22, 2019, at 17:13 , Alex Tweedly via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> Beware CARP !!   (or, very similarly, HSRP or VRRP).
> 
> In essence, there are a number of routers, which share a single MAC address - and it is passed between them (so there is always one active router and only it responds to the shared MAC address). Meanwhile they each use their own MAC address to run their routing protocols, and the HSRP.
> 
> Gives fast, easy and transparent fail-over (but with some pitfalls), so AFAIK not very widely used.
> 
> Alex.
> 
> P.S.  within Cisco, the engineering name for this was CRAP - but pressure form the marketing guys changed it, initally to CARP, and then to HSRP before it was released.





More information about the use-livecode mailing list