Configuring IPMP Groups

This section provides procedures for planning and configuring IPMP groups. The overview in Chapter 5, Introduction to IPMP describes the implementation of an IPMP group as an interface. Thus, in this chapter, the terms IPMP group and IPMP interface are used interchangeably.

How to Plan an IPMP Group
How to Configure an IPMP Group That Uses DHCP
How to Manually Configure an Active-Active IPMP Group
How to Manually Configure an Active-Standby IPMP Group

How to Plan an IPMP Group

The following procedure includes the required planning tasks and information to be gathered prior to configuring an IPMP group. The tasks do not have to be performed in sequence.

Note - You must configure only one IPMP group for each subnet or L2 broadcast domain. For more information, see Rules for Using IPMP.

Determine the general IPMP configuration that would suit your needs.
Your IPMP configuration depends on the network requirements to handle the type of traffic that is hosted on your system. IPMP spreads outbound network packets across the IPMP group's interfaces and thus improves network throughput. However, for a given TCP connection, inbound traffic normally follows only one physical path to minimize the risk of processing out-of-order packets.
Thus, if your network handles a huge volume of outbound traffic, configuring many interfaces into an IPMP group can improve network performance. If instead the system hosts heavy inbound traffic, then having a large number of interfaces in the group does not necessarily improve performance by load-spreading traffic. However, having more underlying interfaces helps to guarantee network availability during interface failure.
Verify that each interface in the group has a unique MAC address.
To configure a unique MAC address for each interface on the system, see How to Ensure That the MAC Address of Each Interface Is Unique in Connecting Systems Using Fixed Network Configuration in Oracle Solaris 11.1.
Ensure that the same set of STREAMS modules is configured and pushed on all interfaces in the IPMP group.
All interfaces in the same group must have the same STREAMS modules configured in the same order.
1. Check the order of STREAMS modules on all interfaces in the prospective IPMP group.
  You can print a list of STREAMS modules by using the ifconfig interface modlist command. For example, here is the ifconfig output for a net0 interface:
```
# ifconfig net0 modlist
    0 arp
    1 ip
    2 e1000g
```
  As the output shows, interfaces normally exist as network drivers directly below the IP module. These interfaces do not require additional configuration.
  However, certain technologies are pushed as STREAMS modules between the IP module and the network driver. If a STREAMS module is stateful, then unexpected behavior can occur on failover, even if you push the same module to all of the interfaces in a group. However, you can use stateless STREAMS modules, provided that you push them in the same order on all interfaces in the IPMP group.
2. Push the modules of each interface in the standard order for the IPMP group.
  For example:
```
# ifconfig net0 modinsert vpnmod@3
```
Use the same IP addressing format on all interfaces in the IPMP group.
If one interface is configured for IPv4, then all interfaces in the IPMP group must be configured for IPv4. For example, if you add IPv6 addressing to one interface, then all interfaces in the IPMP group must be configured for IPv6 support.
Determine the type of failure detection that you want to implement.
For example, if you want to implement probe-based failure detection, then you must configure test addresses on the underlying interfaces. For related information, see Failure Detection in IPMP.
Ensure that all interfaces in the IPMP group are connected to the same local network.
For example, you can configure Ethernet switches on the same IP subnet into an IPMP group. You can configure any number of interfaces into an IPMP group.

Note - You can also configure a single-interface IPMP group, for example, if your system has only one physical interface. For related information, see Types of IPMP Interface Configurations.
Ensure that the IPMP group does not contain interfaces with different network media types.
The interfaces that are grouped together must be of the same interface type. For example, you cannot combine Ethernet and Token Ring interfaces in an IPMP group. As another example, you cannot combine a Token bus interface with asynchronous transfer mode (ATM) interfaces in the same IPMP group.
For IPMP with ATM interfaces, configure the ATM interfaces in LAN emulation mode.
IPMP is not supported for interfaces using Classical IP over ATM technology as defined in IETF RFC 1577and IETF RFC 2225.

How to Configure an IPMP Group That Uses DHCP

A multiple-interfaced IPMP group can be configured with active-active interfaces or active-standby interfaces. For related information, see Types of IPMP Interface Configurations. The following procedure describes how to configure an active-standby IPMP group by using DHCP.

Before You Begin

Make sure that IP interfaces that will be in the prospective IPMP group have been correctly configured over the system's network datalinks. For procedures to configure links and IP interfaces, see How to Configure an IP Interface in Connecting Systems Using Fixed Network Configuration in Oracle Solaris 11.1. You can create an IPMP interface even if underlying IP interfaces have not yet been created. However, without created underlying IP interfaces, subsequent configurations on the IPMP interface will fail.

Additionally, if you are using a SPARC based system, configure a unique MAC address for each interface. For the procedures, see How to Ensure That the MAC Address of Each Interface Is Unique in Connecting Systems Using Fixed Network Configuration in Oracle Solaris 11.1.

Finally, if you are using DHCP, make sure that the underlying interfaces have infinite leases. Otherwise, if an IPMP group failure occurs, the test addresses will expire and the in.mpathd daemon will then disable probe-based failure detection and link-based failure detection will be used. If link-based failure detection discovers that the interface is functioning, the daemon might erroneously report that the interface has been repaired. For more information about configuring DHCP, refer to Working With DHCP in Oracle Solaris 11.1.

Become an administrator.
For more information, see How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.
Create an IPMP interface.
```
# ipadm create-ipmp ipmp-interface
```
where ipmp-interface specifies the name of the IPMP interface. You can assign any meaningful name to the IPMP interface. As with any IP interface, the name consists of a string and a number, for example, ipmp0.
Create the underlying IP interfaces if they do not yet exist.
```
# ipadm create-ip under-interface
```
where under-interface refers to the IP interface that you will add to the IPMP group.
Add underlying IP interfaces that will contain test addresses to the IPMP group.
```
# ipadm add-ipmp -i under-interface1 [-i under-interface2 ...] ipmp-interface
```
You can add as many IP interfaces to the IPMP group as are available on the system.
Have DHCP configure and manage the data addresses on the IPMP interface.
```
# ipadm create-addr -T dhcp ipmp-interface
```
Step 5 associates the address provided by the DHCP server with an address object. The address object uniquely identifies the IP address by using the format interface/address-type, for example, ipmp0/v4. For more information about the address object, see How to Configure an IP Interface in Connecting Systems Using Fixed Network Configuration in Oracle Solaris 11.1
If you use probe-based failure detection with test addresses, have DHCP manage the test addresses on the underlying interfaces.
Issue the following command for each underlying interface of the IPMP group.
```
# ipadm create-addr -T dhcp under-interface
```
The address object that is automatically created by Step 6 uses the format under-interface/address-type, for example, net0/v4.

Example 6-2 Configuring an IPMP Group With DHCP

This example shows how to configure an active-standby IPMP group with DHCP and is based on the following scenario:

Three underlying interfaces net0, net1, and net2 are configured into an IPMP group.
The IPMP interface ipmp0 shares the same name with the IPMP group.
net2 is the designated standby interface.
All the underlying interfaces are assigned test addresses.

First, the administrator creates the IPMP interface.

# ipadm create-ipmp ipmp0

Next, the administrator creates the underlying IP interfaces and adds them to the IPMP interface.

# ipadm create-ip net0
# ipadm create-ip net1
# ipadm create-ip net2

# ipadm add-ipmp -i net0 -i net1 -i net2 ipmp0

Next, the administrator assigns DHCP-managed IP addresses to the IPMP interface. IP addresses assigned to the IPMP interface are data addresses. In this example, the IPMP interface has two data addresses.

# ipadm create-addr -T dhcp ipmp0
ipadm: ipmp0/v4
# ipadm create-addr -T dhcp ipmp0
ipadm: ipmp0/v4a

Next, the administrator assigns DHCP-managed IP addresses to the underlying IP interfaces of the IPMP group. IP addresses assigned to the underlying interfaces are test addresses to be used for probe-based failure detection.

# ipadm create-addr -T dhcp net0
ipadm: net0/v4
# ipadm create-addr -T dhcp net1
ipadm: net1/v4
# ipadm create-addr -T dhcp net2
ipadm net2/v4

Finally, the administrator configures net2 to become a standby interface.

# ipadm set-ifprop -p standby=on net2

How to Manually Configure an Active-Active IPMP Group

The following procedure describes how to manually configure an active-active IPMP group. In this procedure, Steps 1-4 describe how to configure a link-based active-active IPMP group. Step 5 describes how to make the link-based configuration probe-based.

Before You Begin

Make sure that IP interfaces that will be in the prospective IPMP group have been correctly configured over the system's network datalinks. For the procedures to configure links and IP interfaces, see How to Configure an IP Interface in Connecting Systems Using Fixed Network Configuration in Oracle Solaris 11.1. You can create an IPMP interface even if underlying IP interfaces do not yet exist. However, subsequent configurations on this IPMP interface will fail.

Become an administrator.
For more information, see How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.
Create an IPMP interface.
```
# ipadm create-ipmp ipmp-interface
```
where ipmp-interface specifies the name of the IPMP interface. You can assign any meaningful name to the IPMP interface. As with any IP interface, the name consists of a string and a number, for example, ipmp0.
Add underlying IP interfaces to the group.
```
# ipadm add-ipmp -i under-interface1 [-i underinterface2 ...] ipmp-interface
```
where under-interface refers to the underlying interface of the IPMP group. You can add as many IP interfaces as are available on the system.

Note - In a dual-stack environment, placing the IPv4 instance of an interface under a particular group automatically places the IPv6 instance under the same group.
Add data addresses to the IPMP interface.
```
# ipadm create-addr -a address ipmp-interface
```
where address can be in CIDR notation.

Note - Only the DNS address of the IPMP group name or IP address is required.
If you use probe-based failure detection with test addresses, add test addresses on the underlying interfaces.
```
# ipadm create-addr -a address under-interface
```
where address can be in CIDR notation. All test IP addresses in an IPMP group must belong to a single IP subnet and therefore using same network prefix.

How to Manually Configure an Active-Standby IPMP Group

For information about standby interfaces, see Types of IPMP Interface Configurations. The following procedure explains how to configures an IPMP group in which one interface is kept as a standby. This interface is deployed only when an active interface in the group fails.

Become an administrator.
For more information, see How to Use Your Assigned Administrative Rights in Oracle Solaris 11.1 Administration: Security Services.
Create an IPMP interface.
```
# ipadm create-ipmp ipmp-interface
```
where ipmp-interface specifies the name of the IPMP interface. You can assign any meaningful name to the IPMP interface. As with any IP interface, the name consists of a string and a number, for example, ipmp0.
Add underlying IP interfaces to the group.
```
# ipadm add-ipmp -i under-interface1 [-i underinterface2 ...] ipmp-interface
```
where under-interface refers to the underlying interface of the IPMP group. You can add as many IP interfaces as are available on the system.

Note - In a dual-stack environment, placing the IPv4 instance of an interface under a particular IPMP group automatically places the IPv6 instance under the same group.
Add data addresses to the IPMP interface.
```
# ipadm create-addr -a address ipmp-interface
```
where address can be in CIDR notation.
If you use probe-based failure detection with test addresses, add test addresses on the underlying interfaces.
```
# ipadm create-addr -a address under-interface
```
where address can be in CIDR notation. All test IP addresses in an IPMP group must belong to a single IP subnet and therefore using same network prefix.
Configure one of the underlying interfaces as a standby interface.
```
# ipadm set-ifprop -p standby=on under-interface
```

Example 6-3 Configuring an Active-Standby IPMP Group

This example shows how to manually create an active-standby IPMP configuration.

First, the administrator creates the IPMP interface.

# ipadm create-ipmp ipmp0

Next, the administrator creates the underlying IP interfaces and adds them to the IPMP interface.

# ipadm create-ip net0
# ipadm create-ip net1
# ipadm create-ip net2

# ipadm add-ipmp -i net0 -i net1 -i net2 ipmp0

Next, the administrator assigns IP addresses to the IPMP interface. IP addresses assigned to the IPMP interface are data addresses. In this example, the IPMP interface has two data addresses.

# ipadm create-addr -a 192.168.10.10/24 ipmp0
ipadm: ipmp0/v4
# ipadm create-addr -a 192.168.10.15/24 ipmp0
ipadm: ipmp0/v4a

The IP address in this example includes a prefixlen property, which is expressed as a decimal number. The prefixlen portion of the IP address specifies the number of left-most contiguous bits of the address that comprise the IPv4 netmask or the IPv6 prefix of the address. The remaining low-order bits define the host part of the address. When the prefixlen property is converted to a text representation of the address, the address contains 1's for the bit positions that are to be used for the network part and 0's for the host part. This property is not supported on the dhcp address object type. For more information, see the ipadm(1M) man page.

Next, the administrator assigns IP addresses to the underlying IP interfaces of the IPMP group. IP addresses assigned to the underlying interfaces are test addresses to be used for probe-based failure detection.

# ipadm create-addr -a 192.168.10.30/24 net0
ipadm: net0/v4
# ipadm create-addr -a 192.168.10.32/24 net1
ipadm: net1/v4
# ipadm create-addr -a 192.168.10.34/24 net2
ipadm: net2/v4

Finally, the administrator configures net2 to become a standby interface.

# ipadm set-ifprop -p standby=on net2

The administrator can view the IPMP configuration by using the ipmpstat command.

# ipmpstat -g
GROUP     GROUPNAME   STATE      FDT        INTERFACES
ipmp0     ipmp0      ok         10.00s     net0 net1 (net2)

# ipmpstat -t
INTERFACE  MODE     TESTADDR        TARGETS
net0       routes   192.168.10.30   192.168.10.1
net1       routes   192.168.10.32   192.168.10.1
net2       routes   192.168.10.34   192.168.10.5

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