Centos 5.5 Two Nic's Only One works at a time

Krzyview · 08-18-2010, 07:45 PM

Hey everyone.

First let me say thanx to this forum I have learned to use linux very well lately do to the posts and answers here.

So now I have run into a problem I can't figure out what's going on.

My situation:

Dell Power Edge Server SC440
1GB ECC RAM
Aprox 400 GB in a Raid setup
One On Boad Gigabit Nic Card (will be referred to as eth0 Network 66.x.x.x Netmask 255.255.255.224 Gateway 66.x.x.98)
One PCI 3 Com TX 100MBPS NIC Card (will be referred to as eth1 Network 74.x.x.x Netmask 255.255.255.224 Gateway 74.x.x.98)

I boot machine up and on load Linux show eth0 & eth1 as starting up normal.

Now i go to ping one of the IP's on eth0 and they return a nice connection.

Now I go to ping one of the IP's on eth1 and I do not get a response.

So I run the command ifup eth1

Once this command finishes running I ping an IP on eth1 and I get a nice quick response.

Now I go to ping an IP on eth0 and eth0 gets no response now.

If I run command ifup eth0

The command finishes running and eth0 and all it's IP's are pingable again but eth1 becomes unresponsive once more.

Any suggestions?

NETSTAT -rnv READOUT:

Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
66.x.x.96 0.0.0.0 255.255.255.224 U 0 0 0 eth1
74.x.x.96 0.0.0.0 255.255.255.224 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 66.253.119.98 0.0.0.0 UG 0 0 0 eth1

blue_print · 08-18-2010, 09:19 PM

It appears like, the default route of one interface is getting disabled, if you try to enable the other interface. You will need to have multiple routes to solve this problem.

http://www.linuxquestions.org/questi...teways-145635/

http://www.generationip.com/document...teway-on-linux

Krzyview · 08-18-2010, 09:37 PM

I look at these explanations and they kind of confuse me.

what is the:

200 eth0
201 eth1

I would be adding to the rt_tables file and am i supposed to add these specific commands to the file to or run these commands at the prompt and they will add themselves.

ip route add 10.2.0.0 dev eth0 src 10.2.0.100 table eth0
ip route add 10.1.0.0 dev eth1 src 10.1.0.10 table eth1

I just need a little more explanation to get the just of what i'm actually doing i don't want to mess this machine up the software built into it is worth 20 g's

Krzyview · 08-21-2010, 11:57 PM

Any help on this would be appreciated by anyone. I can't figure out why the second the route drops everytime.

NETSTAT READOUT

Code:

Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
66.XXX.XXX.96   0.0.0.0         255.255.255.224 U         0 0          0 eth1
74.XXX.XXX.96   0.0.0.0         255.255.255.224 U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth1
0.0.0.0         66.XXX.XXX.98   0.0.0.0         UG        0 0          0 eth1
0.0.0.0         74.XXX.XXX.98   0.0.0.0         UG        0 0          0 eth0

ETHTOOL ETH1 READOUT

Code:

[root@kvrobo ~]# ethtool eth1
Settings for eth1:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Half
        Port: MII
        PHYAD: 24
        Transceiver: internal
        Auto-negotiation: on
        Current message level: 0x00000001 (1)
        Link detected: yes

ETHTOOL ETH0 READOUT

Code:

[root@kvrobo ~]# ethtool eth0
Settings for eth0:
        Supported ports: [ TP ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Half 1000baseT/Full
        Advertised auto-negotiation: Yes
        Speed: 100Mb/s
        Duplex: Full
        Port: Twisted Pair
        PHYAD: 1
        Transceiver: internal
        Auto-negotiation: on
        Supports Wake-on: g
        Wake-on: g
        Current message level: 0x000000ff (255)
        Link detected: yes

Eth0 Shows a link is detected but it stays unroutable.