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I have a Red Hat ES 6 server that I want to use the additional NIC's for additional throughput. Originally I wanted to link the cards together but the network ...
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  1. #1
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    Dual Nic's different networks


    I have a Red Hat ES 6 server that I want to use the additional NIC's for additional throughput. Originally I wanted to link the cards together but the network team would not let me do that.

    So they suggested placing another NIC in my lab network and configure the server to use that NIC for local traffic.

    My question is every time I turn on the NIC card all traffic coming to my server fails on both networks. So if there something special I have to do in order to traffic moving on both networks.

    My network configuration is as follows:

    eth0: 165.190.168.x/16
    eth6: 10.2.2.x/24

    Any help would be great thanks.
    Grimm

  2. #2
    Super Moderator Roxoff's Avatar
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    To do this successfully, you need to configure network routing information. It's not a complicated subject but it does require that you understand a little about how routes are defined, what subnet masks mean, and how to insert values into the routing table. These matters are probably a bit much to squeeze into a thread here, but there is extensive information on the Internet.

    You could try some of these for a little bit of guidance:

    Guide to IP Layer Network Administration with Linux
    Simple Routing

    If there's bits of this that you struggle to understand, don't be afraid to ask us questions.
    Linux user #126863 - see http://linuxcounter.net/

  3. #3
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    I did insert a route into the routing table, but that did nothing to help.

    Maybe my route syntax was off slightly, should I not use a gateway and only specify the Ethernet interface. Also what I thought was weird was IP communication on my external NIC failed when the internal NIC was active.

  4. #4
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    You may or may not need specific routing information, keep that in mind.

    I'd try to isolate the problem: have you confirmed physical connectivity for both NICs? I.e., do you get a link light on both of them (particularly eth6 since you know eth0 works)? You can use ethtool to confirm the link in software, e.g.

    Code:
    ethtool ethN|grep Link\ detected
    Does eth6 work if eth0 is temporarily brought down/disabled?

    You've shown what your configuration is, but trying showing your current state:

    Code:
    ip a;route -n

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    I am able to ping both IP's assigned to the server at the server. As soon as I either try to ping another computer or ping the server from another computer is a no go.

    Grimm

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    Now we know your eth ip addresses.
    you said you are pinging different ips. enter corresponding ip adn hostname. I will try to get picture.

    source ip and host:
    dest ip and host:

    source ip and host:
    dest ip and host:

    --
    Regards,
    Sachin

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    Sorry for the delay, I will have to plan a outage to test this since the server I am trying to do this one of my production servers.

    I should be as simple as adding an additional route to the routing table with no gateway and goes out the needed NIC card correct?

    Grimm

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    Redhat Second NIC Card not Pinging

    This is more than likely related to the reverse path filtering enabled by default on RHEL 6 which can be filtering your packets. I would suggest you check that out. Check out How to get Redhat 6.2 Linux Second NIC to Ping - Virtualization Team as it has a good explanation of that and how to resolve it.

    If this help, please reward points or mark it as solved at least .

    Thanks,
    Erick
    Linux 2 Aix Blog



    Quote Originally Posted by grimm08 View Post
    I have a Red Hat ES 6 server that I want to use the additional NIC's for additional throughput. Originally I wanted to link the cards together but the network team would not let me do that.

    So they suggested placing another NIC in my lab network and configure the server to use that NIC for local traffic.

    My question is every time I turn on the NIC card all traffic coming to my server fails on both networks. So if there something special I have to do in order to traffic moving on both networks.

    My network configuration is as follows:

    eth0: 165.190.168.x/16
    eth6: 10.2.2.x/24

    Any help would be great thanks.
    Grimm

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