How do I create a unique ID in VxWorks 6.8?

How can I create a unique ID in VxWorks 6.8 that is unique on a closed network ?

Each device on the network requires an associated ID, set it once at startup and save it until shutdown. They don't have to be random or cryptographically secure - just unique on a closed network.

The available length is 6 bytes .

Limitations:

• Devices can boot immediately (or very close to each other), as well as separate in time
• Devices can vary in types / architectures (however, each one supports dTSEC
  
  or eTSEC
  
  )
• Devices start with the same (at least or similar) VxWorks 6.8 Kernel
• ID cannot be set manually or hardcoded
• No third party libraries
• No network connection / negotiation

I've made some testing and development attempts using some kind of "random voodoo" (see code below for example); they have worked without collision so far, but I'm not sure if they are unique enough to stay safe.

I need a real solution .

I am currently using nanosecond time CLOCK_MONOTONIC

and ID for each microcontroller architecture:

#ifdef ARCH_1
# define MC_ARCH_ID    0x01
#elif defined(ARCH_2)
# define MC_ARCH_ID    0x02
/* ... */
#else
# define MC_ARCH_ID    0x00
#endif /* MC_ARCH_ID */

/* ... */

char id[6];

struct timespec tspec;
clock_gettime(CLOCK_MONOTONIC, &tspec);

UINT32 t = htonl(tspec.tv_nsec); /* consistent endian */

id[0] = MC_ARCH_ID; /* 1 Byte ID set for each arch. */
id[1] = (UINT8) ((UINT8*) &t)[0];
id[2] = (UINT8) ((UINT8*) &t)[1];
id[3] = (UINT8) ((UINT8*) &t)[2];
id[4] = (UINT8) ((UINT8*) &t)[3];
id[5] = 0x00; /* Not used yet */

      

        
        
        
      

    

(Hopefully) monotonous nanoseconds are different throughout the network (remember: these IDs are set once at startup) - hence the ID is "unique". But, as "hopefully" points out, there is a chance that it is not. Time is not the best choice here.

I considered using a MAC address as a better and more secure solution. Unfortunately

char mac[6];
muxIoctl(muxCookie, EIOCGADDR, mac);

      

        
        
        
      

    

only returns garbage.