Redundant NICs on Solaris
By Tom Kranz, May 13, 2004
You have your resilient network in place. Dual switches, dual routers, HSRP, failover, redundant firewalls -- they're all there. Now, what about your Sun boxes? Having two network interface cards (NICs) on your Solaris server, with the primary NIC failing over to the secondary, seems like an obvious and easy task, yet there are many pitfalls that make it unnecessarily complicated. In this article, I'm going to explore how to provide redundant NICs simply and cheaply.
Listing 2 /etc/rcS.d/S31scnd_int
#!/sbin/sh
#
# 2001-01-30 Tom Kranz ([email protected])
#
# This script will config the 2nd interface on bootup, but not bring it up
# Our redundant-interface script will do that for us
# We can't use /etc/hostname.<int> and /etc/hosts entries, as the boot
# sequence will automatically ifconfig up all interfaces configured that way
#
# If things are lovey dovey, we have an exit code of 0.
# If there's no config file, that's bad, so we print an error message and bomb
# with an exit code of 2
PATH=/usr/bin:/usr/sbin:/sbin ; export PATH
# We'll pull the redundant interface name from a config file
if [ -r /etc/redundant.int ]; then
INT=`cat /etc/redundant.int`
else
echo
echo "Warning:"
echo "/etc/redundant.int must exist, containing the redundant interface n
ame!"
echo
echo " eg. qfe0"
echo
exit 2
fi
# Let's get ready to rumble!
/sbin/ifconfig $INT plumb
# Let's find out what our hostname is, shall we?
hostname=`cat /etc/hostname.hme0`
# We'll also need an address, I'm guessing
addr=`cat /etc/hosts | grep $hostname | cut -f1`
# Now we'll config the interface, but keep it down
/sbin/ifconfig $INT inet $addr netmask + broadcast + down >/dev/null 2>&1
# It's only polite to let people know what's just been going on
echo
echo "$INT has been configured as the redundant interface"
echo
exit 0
