[Raion]

Unless you're dead set on manually entering a static IP on the client side.  Please use DHCP like a normal client to make life easier. This will automatically also enter the resolv.conf details as well!

chkconfig network on
chkconfig autoconfig_ipaddress on
chkconfig routed on

Even if you want a static IP you should enter as a DHCP reservation on the DHCP server side.

Also network or not, disable esp service, it's the old remote support system from SGI and it takes an enormous amount of resources for doing nothing anymore turning it off is the first thing you should do on a new system.

chkconfig esp off

Assuming you don't have a cabling or hardware problem things should be working now.  Irix did support IPv6 but I don't have the details of that right now.

I'm 99% sure that IRIX doesn't have a DHCP client in 5.3. Unless you use 5.3, please don't assume it has certain creature comforts.

IRIX 5.3 doesn't have DHCP, it doesn't have a 64-bit environment and the routing setup is very different.