Configure network interface with multicast address in linux

In this post going to see how to configure network interface with multicast address in linux.

Multicast will send information to a group of destination simultaneously.

Most probably class D(224.0.0.0 – 239.255.255.255) IP Address used in multicasting

Enable/ Disable Multicast:

Enabling Multicast:

#ifconfig eth0 multicast

once enabled check using #ifconfig eth0 command and you can find a line like below from the output of this command.

UP BROADCAST RUNNING MULTICAST MTU:1500  Metric:1

Disbaling muticast:

follow the same command to check the status

UP BROADCAST MTU:1500  Metric:1

We could see there is no word mentioned in this output like “MULTICAST”

Check whether multicast enabled in Kernel or not.

#grep -i multi /boot/config-<Kernel version>
* CONFIG_IP_MULTICAST=y  #if “CONFIG_IP_MULTICAST” value mentioned as “n” then multicast disabled. We should make it as “y” (yes)
* CONFIG_IP_ROUTER=y
* CONFIG_IP_MROUTE=y
* CONFIG_NET_IPIP=y

Configure Network interface to send muticast traffic over the network:

We should add a default gateway to multicast traffic, to the specific Network Interface. Use the below command to add default route

# route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0

Then check the default route

#  route -n

You will get output like below

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
224.0.0.0       0.0.0.0         240.0.0.0       U     0      0        0 eth0

Command to check the multicast group in our host

# cat proc/net/igmp

From the above commans will get output with multicast address for eth0 interface.

Now we configured a network interface with multicast address.