How to Create a Multihomed Host

1. On the prospective multihomed host, assume the Primary Administrator role, or become superuser.

   The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

2. Configure and plumb each additional network interface that was not configured as part of the Solaris OS installation.

   Refer to How to Configure an IP Interface After System Installation in System Administration Guide: Network Interfaces and Network Virtualization.

3. Verify that IP forwarding is not enabled on the multihomed host.

   # routeadm

   The routeadm command without options reports the state of the routing daemons. The following output from routeadm shows that IPv4 forwarding is enabled:

   Configuration Current Current Option Configuration System State --------------------------------------------------------------- IPv4 routing disabled disabled IPv6 routing disabled disabled IPv4 forwarding enabled disabled IPv6 forwarding disabled disabled Routing services "route:default ripng:default"

4. Turn off packet forwarding, if it is enabled on the system.

   Use either of the following commands:

   • For the routeadm command, type the following:

     # routeadm -d ipv4-forwarding -u

   • To use SMF, type the following:

     # svcadm disable ipv4-forwarding

5. (Optional) Turn on dynamic routing for the multihomed host.

   Use either of the following commands to enable the in.routed daemon:

   • For the routeadm command, type the following:

     # routeadm -e ipv4-routing -u

   • To use SMF, type the following:

     # svcadm enable route:default

Example 5–6 Configuring a Multihomed Host

The following example shows how to configure the multihomed host that is shown in Figure 5–3. In the example, the system has the host name hostc. This host has two interfaces, which are both connected to network 192.168.5.0.

To begin, you would display the status of the system's interfaces.

# dladm show-link
LINK     CLASS     MTU     STATE     OVER
hme0     phys      1500    up        --
qfe0     phys      1500    up        --
qfe1     phys      1500    up        --
qfe2     phys      1500    up        --
qfe3     phys      1500    up        --# ifconfig -a
lo0: flags=1000849 <UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000 
hme0: flags=1000843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
      inet 192.168.5.82 netmask ff000000 broadcast 192.255.255.255
      ether 8:0:20:c1:1b:c6 
 

The dladm show-link command reports that hostc has two interfaces with a total of five possible links. However, only hme0 has been plumbed. To configure hostc as a multihomed host, you must add qfe0 or another link on the qfe NIC. First, you would physically connect the qfe0 interface to the 192.168.5.0 network. Then you would plumb the qfe0 interface, and make the interface persist across reboots.

# ifconfig qf0 plumb up
# ifconfig qfe0 192.168.5.85
# ifconfig -a
lo0: flags=1000849 <UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1
        inet 127.0.0.1 netmask ff000000 
hme0: flags=1000843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
        inet 192.168.5.82 netmask ff0000 broadcast 192.255.255.255
        ether 8:0:20:c1:1b:c6 
qfe0: flags=1000843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
        inet 192.168.5.85 netmask ff000000 broadcast 192.255.255.255
        ether 8:0:20:e1:3b:c4
 # vi /etc/hostname.qfe0
192.168.5.85
255.0.0.0

Reboot the system, using the reconfiguration command:

# reboot -- -r

Next, you would add the qfe0 interface to the hosts database:

# vi /etc/inet/hosts
127.0.0.1           localhost
192.168.5.82        host3    #primary network interface for host3
192.168.5.85        host3-2  #second interface

Then, you would check the state of packet forwarding and routing on host3:

# routeadm
              Configuration   Current              Current
                     Option   Configuration        System State
---------------------------------------------------------------
               IPv4 routing   enabled              enabled
               IPv6 routing   disabled             disabled
            IPv4 forwarding   enabled              enabled
            IPv6 forwarding   disabled             disabled

           Routing services   "route:default ripng:default"

The routeadm command reports that dynamic routing through the in.routed daemon and packet forwarding are currently enabled. However, you would need to disable packet forwarding:

# svcadm disable ipv4-forwarding

You can also use the routeadm commands as shown in How to Create a Multihomed Host to turn off packet forwarding. When packet forwarding is disabled, host3 becomes a multihomed host.