multicastaddress

[otto_3]

does anyone know how to set the multicast address?
or can i disable multicast on some interfaces?

[John Palmer]

You can set the broadcast address with ifconfig (man ifconfig).

Something like:

ifconfig lan?

netmask broadcast

I don't think you can disable it, if you omit it, ifconfig defaults it to the network address with a host address of all 1's.

Regards,
John

[Ron Kinner]

It's not clear what you are trying to do.

If you are sending multicast packets then the application which sends them will set the address it wants to use based on input from the administrator of the application.

If you are receiving them then your receiving application will have a mechanism to "tune" to the correct address which was set by the sending station. Unless an application is running which wants to listen to a multicast the NIC pretty much ignores multicast traffic. The only exceptions are 224.0.0.1 which is a broadcast to all multicast capable stations and 224.0.0.2 which is a broadcast to all multicast capable routers (which your box would become if it were running mrouted.) You can try
ping 224.0.0.1
and see who is multicast capable. (I suppose this can be turned off by
ndd -set ip_respond_to_echo_broadcast 0
if you want to stop it but it will stop resonding to all pings.)

ifconfig does not appear to have any effect on multicasting other than telling you if your NIC and associated TCP/IP stack are multicast capable. The broadcast address is not the multicast address.

There are two unsupported ndd options which appear to do something with multicast but there is no help on them in my version of 11.0 so I can't tell you what they do.

ip_mc_filter_command
ip_mc_filter_status

You may want to read:

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90748/B2355-90748_top.html&con=/hpux/onlinedocs/B2355-90748/00/00/43-con.html&toc=/hpux/onlinedocs/B2355-90748/00/00/43-toc.html&searchterms=multicast&queryid=20021113-082325

and

http://www.cisco.com/en/US/tech/tk648/tk363/tech_brief09186a00800a4415.html

Ron