/etc/sysconfig/network-scripts/ifcfg-eth0:1

DEVICE=eth0:1
BOOTPROTO=static
IPADDR=10.y.y.y
NETMASK=255.y.y.y
GATEWAY=10.y.y.y
ONBOOT=yes


/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
BOOTPROTO=static
IPADDR=10.x.x.x
NETMASK=255.x.x.x
GATEWAY=10.x.x.x
ONBOOT=yes

# ifconfig -a
eth0      Lien encap:Ethernet  HWaddr XXXXXXXXXXXXXXXX
          inet adr:10.x.x.x  Bcast:10.x.x.x  Masque:255.x.x.x
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:236370130 errors:0 dropped:0 overruns:2174 frame:0
          TX packets:30791849 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:100
          RX bytes:3771461428 (3596.7 Mb)  TX bytes:109273263 (104.2 Mb)

eth0:1    Lien encap:Ethernet  HWaddr YYYYYYYYYYYYYYYY
          inet adr:10.y.y.y  Bcast:10.y.y.y  Masque:255.y.y.y
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 lg file transmission:100
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)