its a fresh installation. during the OS setup, it did not prompt for IP, netmask and gateway. using Solaris 10 08/07 update 4. I tried to plumb manually but encountered no such interface error. but nxge interfaces can be greped from the /etc/path_to_inst file.
getting similar error on bootup/messages file
WARNING: consconfig: cannot find driver for screen device
WARNING: ncp0: unable to determine ncp (cpu) binding (ncp)
Booting to milestone "milestone/single-user:default".
WARNING: ncp0: unable to determine ncp (cpu) binding (ncp)
Failed to plumb IPv4 interface(s): nxge0
Feb 2 17:58:56 svc.startd[7]: svc:/network/physical:default: Method "/lib/svc/m
ethod/net-physical" failed with exit status 96.
Feb 2 17:58:56 svc.startd[7]: network/physical:default misconfigured: transitio
ned to maintenance (see 'svcs -xv' for details)
Hostname: xxxxxxx
Hi guys, i updated the system with the latest kernel patch 138138-01 and did a re-conf boot. The network ip plumbed up successfully 
Boot device: /pci@400/pci@0/pci@8/scsi@0/disk@0,0:a File and args: -r
SunOS Release 5.10 Version Generic_138888-01 64-bit
Copyright 1983-2008 Sun Microsystems, Inc. All rights reserved.
Use is subject to license terms.
ip_arp_done: init failed
NOTICE: nxge0: xcvr addr:0x1d - link is down
Hostname: xxxxxxx
NOTICE: nxge1: xcvr addr:0x1c - link is up 1000 Mbps full duplex
NOTICE: nxge1: xcvr addr:0x1c - link is down
NOTICE: nxge0: xcvr addr:0x1d - link is up 1000 Mbps full duplex
Configuring devices.
Loading smf(5) service descriptions: 6/37
root@xxxxx # ifconfig -a
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index
1
inet 127.0.0.1 netmask ff000000
nxge0: flags=201000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4,CoS> mtu 1500 index 2
inet 165.114.106.70 netmask ffffff00 broadcast 165.114.106.255
ether 0:21:28:26:5c:86
root@xxxxx # bash
root@xxxxx # more /etc/defaultrouter
165.114.106.1
root@xxxxx # ping 165.114.106.1
165.114.106.1 is alive
root@xxxxx # netstat -rn
Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ---------- ---------
default 165.114.106.1 UG 1 0
165.114.106.0 165.114.106.70 U 1 1 nxge0
224.0.0.0 165.114.106.70 U 1 0 nxge0
127.0.0.1 127.0.0.1 UH 8 520 lo0
root@xxxxx # ifconfig nxge1 plumb
root@xxxxx # Feb 3 14:12:34 sgs1fs03 nxge: NOTICE: nxge1: xcvr addr:0x1c - l
ink is down
root@xxxxx # ifconfig -a
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index
1
inet 127.0.0.1 netmask ff000000
nxge0: flags=201000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4,CoS> mtu 1500 index 2
inet 165.114.106.70 netmask ffffff00 broadcast 165.114.106.255
ether 0:21:28:26:5c:86
nxge1: flags=201000802<BROADCAST,MULTICAST,IPv4,CoS> mtu 1500 index 3
inet 0.0.0.0 netmask 0
ether 0:21:28:26:5c:87
root@xxxxx # ifconfig nxge1 192.23.23.1 netmask 255.255.255.0 broadcast + up
root@xxxxx # ifconfig -a
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index
1
inet 127.0.0.1 netmask ff000000
nxge0: flags=201000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4,CoS> mtu 1500 index 2
inet 165.114.106.70 netmask ffffff00 broadcast 165.114.106.255
ether 0:21:28:26:5c:86
nxge1: flags=201000803<UP,BROADCAST,MULTICAST,IPv4,CoS> mtu 1500 index 3
inet 192.23.23.1 netmask ffffff00 broadcast 192.23.23.255
ether 0:21:28:26:5c:87
hi
for y info
Minimum Supported Solaris[tm] Operating Environment Versions T5240
Solaris 10 8/07 (U4) plus patches *
Yes I knew that, the default patch level was already 137137-09, which is not too old right? But after applying 138888-01, all went fine