Rules for Using IPMP

IPMP group configuration is determined by your specific system configuration.

Observe the following rules for IPMP configuration:

1. Multiple IP interfaces that are on the same LAN must be configured into an IPMP group. A LAN broadly refers to a variety of local network configurations, including VLANs and both wired and wireless local networks with nodes that belong to the same link-layer broadcast domain.

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   Note -  Multiple IPMP groups on the same link layer (L2) broadcast domain are unsupported. An L2 broadcast domain typically maps to a specific subnet. Therefore, you must configure only one IPMP group per subnet. Note also that some exceptions to this rule apply, for example, in the case of certain engineered systems that are provided by Oracle. For further clarification, contact your Oracle support representative.

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2. Underlying IP interfaces of an IPMP group must not span different LANs.

   For example, suppose that a system with three interfaces is connected to two separate LANs. Two IP interfaces connect to one LAN while a single IP interface connects to the other LAN. In this case, the two IP interfaces connecting to the first LAN must be configured as an IPMP group, as required by the first rule. In compliance with the second rule, the single IP interface that connects to the second LAN cannot become a member of that IPMP group. No IPMP configuration is required for the single IP interface. However, you can configure the single interface into an IPMP group to monitor the interface's availability. Single-interface IPMP configuration is discussed further in Types of IPMP Interface Configurations.

   Consider another case where the link to the first LAN consists of three IP interfaces while the other link consists of two interfaces. This setup requires the configuration of two IPMP groups: a three-interface group that connects to the first LAN, and a two-interface group that connects to the second LAN.

3. All interfaces in the same group must have the same STREAMS modules configured in the same order. When planning an IPMP group, first check the order of STREAMS modules on all interfaces in the prospective IPMP group, then push the modules of each interface in the standard order for the IPMP group. To print a list of STREAMS modules, use 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 previous 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.

   The following example shows the command you might use to use to push the modules of each interface in the standard order for the IPMP group:

   # ifconfig net0 modinsert vpnmod@3

   For step-by-step instructions on planning an IPMP group, see How to Plan an IPMP Group.