SUMMARY: Multiple Ethernet Cards

From: Bruce Rosen (
Date: Mon Jul 28 1997 - 12:56:40 CDT

Platform: SPARCserver 1000E
OS : Solaris 2.5.1

I would like to install multiple Ethernet cards and assign them IP
addresses all in the same IP class (198.185.178.*).

Sun does not support this configuration. Please let me know if you are
successfully running with this configuration and if you had to take any
special measures or had any significant problems setting it up. Thanks.

Thanks to everyone who resonded (too many to list). I apologize for the
delay in summarizing the responses. By default, Sun Ethernet interfaces all
use the same MAC address. So, to use multiple interfaces on the same
subnet, one must assign unique MAC addresses using the ifconfig command
(see 'man ifconfig' for more information):

        ifconfig interface-name ethers 8:0:20:x:y:z

Some heuristics recommended for assigning unique MAC addresses include
incrementing z sequentially for each interface or using the MAC address of
a card no longer in service (if you have an old card lying around).

Consider adding the ifconfig command(s) to a startup file. Suggestions
include /etc/init.d/rootusr (in the loop between plumbing the interface and
bringing it up), /etc/rc2.d, and /etc/init.d/inetsvc. Remember to add an
entry in /etc/hosts for each interface and to create the appropriate
/etc/hostname.leX files containing the names of the interfaces.

Other considerations:

1. maybe turn off routing using ndd -set /dev/ip ip_forwarding 0
2. maybe turn off ip_send_redirects

I will be trying some version of these procedures soon. If you are in the
same situation and would like me to keep you updated on my progress, just
send me email.

Bruce Rosen
NASA COTF (Classroom of the Future)

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