How to disable the NIC, then the connection is normal ?

[Edward S.P. Leung]

Dear All,

Mine is Fedora Core 6 :
eth0 ( Internet )
eth1 ( Intranet )

Now, due to the envoriment problem, the eth1 need to be disable at this 
moment, so I try to do the following config
[root at host1 ~]$ cat /etc/sysconfig/network-scripts/ifcfg-eth1
# Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+
DEVICE=eth1
BROADCAST=192.168.1.255
# HWADDR=00:17:31:7E:F8:34
IPADDR=192.168.1.254
# IPV6ADDR=
# IPV6PREFIX=
NETMASK=255.255.255.0
NETWORK=192.168.1.0
# ONBOOT=yes
ONBOOT=no
[root at host1 ~]$

After reboot the network function, the server machine can't to connect 
with Internet again :
[root at host1 ~]$ ping -c 3 202.175.xxx.xxx
PING 202.175.xxx.xxx (202.175.xxx.xxx) 56(84) bytes of data.
 From 202.175.xxx.xxx icmp_seq=1 Destination Host Unreachable
 From 202.175.xxx.xxx icmp_seq=2 Destination Host Unreachable
 From 202.175.xxx.xxx icmp_seq=3 Destination Host Unreachable

So, how must I modify the config of eth1 interface, then the connection 
of Internet will be successful ?

Thanks !

Edward.