Question : Setup multicast on Fedora 4

Hi All:

I am a newbie for linux, I want to setup a tomcat clustering, which requires the server have multicast turned on so they can send each other session data.

I read some material on the net about run the make configure. After I answered Yes to the corresonding Multicast option. In the generated .configure file I cannot find any multicast option specified, only the broadcast option.

What option can I see, is that
CONFIG_IP_MROUTE and CONFIG_IP_PIMSM_V2???

Or is there a network monitoring tool I can see the traffic that come out of/from this linux box?

Thanks
pat

Answer : Setup multicast on Fedora 4

Bcast IS NOT Multicast...,

Broadcast is LAN only, whereas multicast can go global.
Bcast uses the ff-ff-ff-ff-ff-ff mac address whereas multicast has
several mac addresses assigned. (01-00-5e-xx-xx-xx) the xx.xx.xx are derived from the last 3 bytes of the ip address in use

In your case I would expect to see 01-00-5e-00-00-04 as mac address. (tcpdump should show this)
see also: http://www.cisco.com/warp/public/473/22.html

Then with 'netstat -anp | grep :46654' should show a udp socket.

224.0.0.1 is a special address, it means ALL multicast enabled systems on the LAN segment.
224.0.0.2 means all Multicast capable routers on a network segment
(224.0.0.5 & 224.0.0.6 are OSPF routing protocol reserved)

(Multicast can only be the lossy udp protocol, because you cannot send one TCP SYN packet to multiple hosts and
receive multiple conflicting connection setups (SYN-ACK))