Configure IPMP network resilience with Multiple NICs in Solaris

IP Multipathing (IPMP) in Sun Solaris enables the load balancing capabilities and resilience for Network connections with multple Network Interface Cards (NIC).

IPMP is mostly used to provide resilience with network connections wherein a Sun Solaris Server with multiple NICs can be configured such that if the primary NIC fails it automatically failover to the secondary NIC on the system. Also, if it is a multi-switch environment then each Network Interface participating in IPMP can be connection to two different switches such that a network connection failure due to a NIC failure or a switch failure can be avoided.

To configure IPMP for resiliency we need to have

1. Virtual IP Address

2. Test IP Address for each NIC.

The Virtual IP is the actual Data IP and the test IPs are the ones used by IPMP to probe a remote target system to check connectivity. The test IP interfaces are marked as “deprecated” which indicates that this IP should be used by applications for any network data transfer. The NICs doesn’t have to be of the same make or have to be the same speed (10/100/1000Mbps). However, they should be of the same kind (Ethernet here)

In our configuration,

192.168.1.100 – Virtual IP

192.168.1.101 – Test IP for ce0 (NIC1)

192.168.1.102 – Test IP for ce1 (NIC2)

appserver – Hostname

appserver-ce0 – Hostname for IP on ce0 interface

appserver-ce1 – Hostname for IP on ce1 interface

Add Host Entries in /etc/hosts

Let’s start with adding the hosts entries for the IP addresses in the /etc/hosts file.

# IPMP group appserver-ipmp
127.0.0.1       localhost
192.168.1.100  appserver        loghost
192.168.1.101  appserver-ce0    loghost
192.168.1.102  appserver-ce1    loghost

Create hostname.ce* files

For every interface on the system create a hostname.ce* file. For us, create the files

hostname.ce0 & hostname.ce1

Edit hostname.ce0

Add the following on the hostname.ce0 file. This is the primary or master interface of the IPMP Pair

appserver-ce0 netmask + broadcast + group appserver-ipmp deprecated -failover up\

addif appserver netmask + broadcast + failover up

Edit hostname.ce1

Add the following on the hostname.ce1 file. This is the secondary or slave interface of the IPMP Pair

appserver-ce1 netmask + broadcast + group appserver-ipmp deprecated \
-failover standby up

where

netmask – sets default netmask values

broadcast – sets default broadcast address

-failover  – indicates that the test IPs should not be failed over

deprecated – indicates that the interface should not be used for data transfer

Now, the configuration is complete and an ifconfig output should look like as follows:

root@ appserver:/$
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
ce0: flags=9040843<UP,BROADCAST,RUNNING,MULTICAST,DEPRECATED,IPv4,NOFAILOVER> mtu 1500 index 2
inet 192.168.1.101 netmask ffffff00 broadcast 192.168.1.255
groupname appserver-ipmp
ether 0:xx:xx:xx:xx:x
ce0:1: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
inet 192.168.1.100 netmask ffffff00 broadcast 192.168.1.255
ce1: flags=69040843<UP,BROADCAST,RUNNING,MULTICAST,DEPRECATED,IPv4,NOFAILOVER,STANDBY,INACTIVE> mtu 1500 index 3
inet 192.168.1.102 netmask ffffff00 broadcast 192.168.1.255
groupname appserver-ipmp
ether 0:xx:xx:xx:xx:x

You can see a new virtual interface for “ce0” is being created as “ce0:1” and the  “ce1” interface status is UP but INACTIVE. Indicating it is up and participating in the IPMP but is  as a standby. Test by pinging the device continously from a remote PC and unplugging the active NIC and you should see no packets drop. Reverse the tests and check if it works OK. Also, if you are on the console, you can see the live link messages (check later from /var/adm/messages)