heinbali01 wrote on Tuesday, June 19, 2018:
I want 8 nodes on my private network to be able to call each other by name, yet I don’t want
any of them to have to be the DNS. LMNR uses TCP mulitcast and NBNS uses UDP broadcast,
so I think I want NBNS.
Correction: LLMNR has no direct relation with TCP, and indeed it does use multicasting. When you use a local name in a browser, it is most likely to start a look-up with LLMNR first. Only after a time-out, it will try the same look-up using NBNS. For this reason I would prefer to use LLMNR.
A second advantage of LLMNR is multi-casting. You can selectively enable multi-cast addresses, so that you only receive the type of messages that you are interested in.
Broadcasting is not specific: either you enable all broadcasting ( and get disturbed very often ), or you disable it.
Can anyone provide an example implementation including the required call-back.
Just enable the proper define(s):
#define ipconfigUSE_LLMNR ( 1 )
#define ipconfigUSE_NBNS ( 1 )
and define the application call-back, returning pdPASS if a match is found:
BaseType_t xApplicationDNSQueryHook( const char *pcName )
/* Determine if a name lookup is for this node. Two names are given
to this node: that returned by pcApplicationHostnameHook() and that set
by mainDEVICE_NICK_NAME. */
if( strcasecmp( pcName, "speaker_01_r" ) == 0 )
xReturn = pdPASS;
else if( strcasecmp( pcName, "audio-output" ) == 0 )
xReturn = pdPASS;
xReturn = pdFAIL;
In this example, the device can be found as follows:
Or as a URL:
Note that local names may not contain a dot. Addresses with a dot will be looked up with DNS.
The following +TCP look-up function is aware of this:
uint32_t FreeRTOS_gethostbyname( const char *pcHostName );
It will either use DNS or LLMNR to find a node.