IP Routing Issue
 

I'm new to linux and I'm having some IP routing issue. Server have 6 eth ports (eth0 to eth5) and I'm using eth4 as my control port. The poroblem is when I bring up the other eth ports and do network restart, I couldn't ssh to the server.

[root@lab ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth0
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth1
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth2
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth3
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth4
202.177.223.0 0.0.0.0 255.255.255.192 U 0 0 0 eth5
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth5
0.0.0.0 202.177.223.61 0.0.0.0 UG 0 0 0 eth5


I manually added a route and I can ssh again to the server.

# route add -net 202.177.223.0 netmask 255.255.255.192 gw 202.177.223.61 eth4

What can be causing this issue and how do I fix it without doing any manual changes?

I suspect your default gateway is not setup correctly.

Post the output of more /etc/sysconfig/network-scripts/ifcfg-ethX where X is 0-5 for your 6 interfaces.

Also post the output of ifconfig -a

Hi Yas,

Here's the output...

[root@lab ~]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:15:17:CF:FD:79
inet addr:202.177.223.43 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST 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 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Memory:fbde0000-fbe00000

eth1 Link encap:Ethernet HWaddr 00:15:17:CF:FD:78
inet addr:202.177.223.44 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST 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 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Memory:fbd80000-fbda0000

eth2 Link encap:Ethernet HWaddr 00:15:17:CF:FD:7B
inet addr:202.177.223.45 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST 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 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Memory:fbce0000-fbd00000

eth3 Link encap:Ethernet HWaddr 00:15:17:CF:FD:7A
inet addr:202.177.223.35 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST 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 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Memory:fbca0000-fbcc0000

eth4 Link encap:Ethernet HWaddr 00:21:28:6B:65:DE
inet addr:202.177.223.42 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:52301 errors:0 dropped:0 overruns:0 frame:0
TX packets:1551 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3295557 (3.1 MiB) TX bytes:200386 (195.6 KiB)
Memory:fbee0000-fbf00000

eth5 Link encap:Ethernet HWaddr 00:21:28:6B:65:DF
inet addr:202.177.223.47 Bcast:202.177.223.63 Mask:255.255.255.192
UP BROADCAST 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 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Memory:fbe60000-fbe80000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:44530 errors:0 dropped:0 overruns:0 frame:0
TX packets:44530 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3802212 (3.6 MiB) TX bytes:3802212 (3.6 MiB)



[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth0
# Intel Corporation 82571EB Gigabit Ethernet Controller (Copper)
DEVICE=eth0
BOOTPROTO=none
IPADDR=202.177.223.43
NETMASK=255.255.255.192
HWADDR=00:15:17:CF:FD:79
ONBOOT=yes


[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth1
# Intel Corporation 82571EB Gigabit Ethernet Controller (Copper)
DEVICE=eth1
BOOTPROTO=none
IPADDR=202.177.223.44
NETMASK=255.255.255.192
NETWORK=202.177.223.0
TYPE=Ethernet
HWADDR=00:15:17:CF:FD:78
ONBOOT=yes


[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth2
# Intel Corporation 82571EB Gigabit Ethernet Controller (Copper)
DEVICE=eth2
BOOTPROTO=none
IPADDR=202.177.223.45
NETMASK=255.255.255.192
NETWORK=202.177.223.0
TYPE=Ethernet
HWADDR=00:15:17:CF:FD:7B
ONBOOT=yes


[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth3
# Intel Corporation 82571EB Gigabit Ethernet Controller (Copper)
DEVICE=eth3
BOOTPROTO=none
IPADDR=202.177.223.35
NETMASK=255.255.255.192
NETWORK=202.177.223.0
TYPE=Ethernet
HWADDR=00:15:17:CF:FD:7A
ONBOOT=yes


[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth4
# Intel Corporation 82575EB Gigabit Network Connection
DEVICE=eth4
BOOTPROTO=none
IPADDR=202.177.223.42
NETMASK=255.255.255.192
GATEWAY=202.177.223.61
NETWORK=202.177.223.0
TYPE=Ethernet
HWADDR=00:21:28:6B:65:DE
ONBOOT=yes


[root@lab ~]# more /etc/sysconfig/network-scripts/ifcfg-eth5
# Intel Corporation 82575EB Gigabit Network Connection
DEVICE=eth5
BOOTPROTO=none
IPADDR=202.177.223.47
NETMASK=255.255.255.192
NETWORK=202.177.223.0
TYPE=Ethernet
HWADDR=00:21:28:6B:65:DF
ONBOOT=yes

Hi

Everything looks OK, other than:

I see this line within all your interface network configuration files.

Are you using static IP's or DHCP? Basically you should set:

OR

Obviously depending on what you're (note the files are case sensitive - so it needs to be exactly as I state above).

Try the above and restart networking/the server - and see if it works.

Also, have you considered interface bonding? I notice you have 6 NIC's; which means it can become problematic to manage - it would be easier if you bonded your interfaces into 3 sets of 2 for example.