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Dual NIC routing fail

George_penilli
Occasional Contributor

Dual NIC routing fail

Hi 

 

I am running HPUX 10.20 & have 2 NIC cards in my HP9000 K360 servers. I have assign two unique IP subnet to both NIC card.

 

But whenever i try to ping on the 176.20.10.78 it return -1 but if i ping the interface it is ok

 

I notice that everytime i ping the 176.20.20.78 the NIC Card that is blinking is Lan1 instead of Lan0

 

And further when i ping 176.20.10.77 from the outside it is reachable but the route from inside the NIC is not able to go out.

 

Please help advise me what is wrong ?

 

Below is the Netconf & also the output of Netstat -rn 

 

INTERFACE_NAME[0]=lan1
IP_ADDRESS[0]=216.131.195.138
SUBNET_MASK[0]=255.255.255.0
BROADCAST_ADDRESS[0]=
LANCONFIG_ARGS[0]="ether"
DHCP_ENABLE[0]=0

 

INTERFACE_NAME[1]=lan0
IP_ADDRESS[1]=176.20.10.77
SUBNET_MASK[1]=255.255.255.0
BROADCAST_ADDRESS[1]=176.20.10.255
LANCONFIG_ARGS[1]="ether"
DHCP_ENABLE[1]=0

ROUTE_DESTINATION[0]=default
ROUTE_MASK[0]=""
ROUTE_GATEWAY[0]=216.131.195.138
ROUTE_COUNT[0]=0
ROUTE_ARGS[0]=""

 

ROUTE_DESTINATION[1]="host 176.20.10.78"
ROUTE_MASK[1]=""
ROUTE_GATEWAY[1]=176.20.10.77
ROUTE_COUNT[1]=0
ROUTE_ARGS[1]=""

 

Netstat -rn (Output) -

Destination                 Gateway                         Flags Refs Use           Interface Pmtu  PmtuTime
127.0.0.1                  127.0.0.1                       UH       0     311          lo0            4608

216.131.195.138  127.0.0.1                       UH       4     2329       lo0            4608

176.20.10.77          127.0.0.1                      UH       0     1069        lo0            4608

176.20.10.78          176.20.10.77              UH       0       0              lan0          1500

default                        216.131.195.138       U                  564333  lan1          1500

216.131.195.0       216.131.195.138       U         9      7832       lan1           1500      

176.20.10.0            176.20.10.77               U         0       0              lan0            1500

1 REPLY
Matti_Kurkela
Honored Contributor

Re: Dual NIC routing fail

1.)

For all routes involving a gateway (including the default gateway route), the ROUTE_COUNT value should be greater than 0. So your "ROUTE_COUNT[0]=0" should be "ROUTE_COUNT[0]=1".

 

2.)

> I notice that everytime i ping the 176.20.20.78 the NIC Card that is blinking is Lan1 instead of Lan0

 

176.20.20.78 is not part of the lan1 network segment, as determined by the combination of lan0 IP 176.20.10.77 and netmask 255.255.255.0. I guess this might be a typo?

 

Because of the incorrect ROUTE_COUNT value on the default gateway route, the default gateway route is listed before the 176.20.10.0 network route in the routing table. When choosing the interface for sending any outgoing IP packet, the first matching entry in the routing table wins - and the default gateway route matches everything. This might be causing the system to attempt to use lan1 instead of lan0  when you're pinging 176.20.10.78.

 

Once the ROUTE_COUNT value of the default gateway route is fixed, the default gateway entry should appear in its proper location, as the last line in the routing table. At that point, you should not need the host route entry for 176.20.10.78 at all: the auto-generated network route 176.20.10.0/255.255.255.0 for lan0 should be enough to cause any traffic with 176.20.10.78 as a destination to be sent out from lan0. So remove or comment out all ROUTE_*[1] lines from your netconf file.

 

And you should use "netstat -rnv" instead of "netstat -rn". Omitting the "-v" option hides the netmasks of the route entries, which are rather important.

MK