Maintaining Routing While Deploying IPMP

When you configure an IPMP group, the IPMP interface inherits the IP addresses of its underlying interfaces to use them as data addresses. The underlying interfaces then receive the IP address 0.0.0.0. Consequently, routes that are defined using specific IP interfaces become lost if these interfaces are subsequently added to an IPMP group.

Loss of routing when configuring IPMP commonly involves the default route and occurs in association with an Oracle Solaris installation. During installation, you are required to define a default route, for which you use an interface in the system, such as the primary interface. Subsequently, you configure an IPMP group by using the same interface on which you defined the default route. After the IPMP configuration, the system can no longer route network packets because the interface's address has been transferred to the IPMP interface.

To ensure that the default route is preserved while you use IPMP, the route must be defined without specifying the interface. In this manner, any interface, including the IPMP interface, can be used for routing. Thus the system can continue to route traffic.

Note - This section uses the primary interface as an example on which the default route is defined. However, the routing loss case applies to any interface that is used for routing and which later becomes part of an IPMP group.

How to Define Routes While Using IPMP

The following procedure explains how to preserve the default route when you configure IPMP.

Log in to the system by using a console.
You must use the console to perform this procedure. If you use the ssh or telnet command to log in, the connection will be lost when you perform the subsequent steps.
(Optional) Display the routes that are defined in the routing table.
```
# netstat -nr
```

Delete the route that is bound to the specific interface.

# route -p delete default gateway-address -ifp interface

Add the route without specifying an interface.
```
# route -p add default gateway-address
```
(Optional) Display the redefined routes.
```
# netstat -nr
```
(Optional) If the information has not changed in the routing table, restart the routing service, then recheck the information in the routing table to make sure the routes have been correctly redefined.
```
# svcadm restart routing-setup
```

Example 6-1 Defining Routes for IPMP

This example assumes that the default route was defined for net0 during the installation.

# netstat -nr
Routing Table: IPv4
 Destination     Gateway       Flags    Ref     Use       Interface
-------------  ------------  --------  -----  -----------  --------
default        10.153.125.1     UG      107    176682262   net0
10.153.125.0   10.153.125.222   U        22    137738792   net0

# route -p delete default 10.153.125.1 -ifp net0
# route -p add default 10.153.125.1

# netstat -nr
Routing Table: IPv4
 Destination     Gateway       Flags    Ref     Use       Interface
-------------  ------------  --------  -----  -----------  --------
default        10.153.125.1     UG      107    176682262
10.153.125.0   10.153.125.222   U        22    137738792   net0

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	Managing Oracle Solaris 11.1 Network Performance Oracle Solaris 11.1 Information Library