IP Multicast (just 'casting, not rcving)

Smith, Gene Gene.Smith at sea.siemens.com
Mon Feb 5 20:45:57 UTC 2001

A while back I asked if multicast was supported in rtems. I have since
realized that I only need to transmit multicast messages, not receive them.
Does anyone know if rtems might support just sending a multicast? When I
try to send a udp packet to a multcast address, eg,, my current
udp code fails in send() with "Network Unreachable" and nothing is
transmitted on the network per tcpdump. Perhaps I need to set a socket
option to tell it the multicast interface, although Steven seems to says you
don't need to set socket options or join a group to just send a multicast.
Any ideas while I continue reading rtems-bsd code and Stevens? 


> -----Original Message-----
> From: suvrat gupta [mailto:suvrat at utstar.com]
> Sent: Tuesday, August 01, 2000 5:16 PM
> To: Smith, Gene
> Subject: Re: IP Multicast
> I looked at it about two months ago. Seemed like most of the 
> IP stack does
> support it..  The ethernet driver needs to support multicast related
> ioctls(add/remove address in the H/W filter).this can be done 
> by usingl
> ether_addmulti() ether_delmulti() functions(you may need to 
> modify them a bit.
> Try using the latest RTEMS code.
> hope this helps. In case you do come to know of some working 
> implementation,
> let me know.
> -suvrat
> "Smith, Gene" wrote:
> > Is IP Multicast actually supported in RTEMS?  If so, has it 
> been used by
> > anyone?  All the drivers in "network" directories seem to 
> say FIXME and
> > ERROR when referring to multicast.  I didn't see multicast 
> mentioned in
> > Networking Suppliment.
> >
> > My application might need some form of multicast.  However, 
> a simple subnet
> > broadcast might do.
> >
> > -Gene

More information about the users mailing list