Two NIC's, metrics question

Posted on 2004-11-28
Last Modified: 2007-12-19
I've two NIC's in my machine, both public IP's.

Traffic is received on both fine, but outbound traffic doesn't go out via the NIC it came in on, it goes out via 114 regardless. Is there a way to change this via metrics or some other method?


Current route table:

IPv4 Route Table
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...00 30 48 72 be 9c ...... Intel(R) PRO/100 S Server Adapter - Packet Sched
uler Miniport
0x10004 ...00 30 48 72 be 9d ...... Intel(R) PRO/1000 MT Network Connection - Pa
cket Scheduler Miniport
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
      5      1      5     10      5     10      5     10      5     10      1      1
Default Gateway:
Persistent Routes:
Question by:rossdagley
    LVL 4

    Expert Comment

    In my opinion you have two options,

    (1) You can alter the metrics to match for each host based route because as it stands your route for (.114) appears to be more attractive than your route for (.124) in the routing table above.



    (2) You can use a router with two ethernet interfaces (or if it supports subinterfaces) and seperate the two IP's into a seperate network using VLSM

    LVL 1

    Author Comment

    All this can only be done with software on Windows 2003 - I cant stick any more hardware in.

    I've adjusted the metrics so their the same, but (for example) if I FTP to, when I get my download, it still comes out over, not 124. :(

    Any ideas?

    LVL 5

    Expert Comment

    LVL 1

    Author Comment

    Not entirely sure I understand that doc from MS.

    Is there really no simple solution for this?

    LVL 11

    Accepted Solution

    > Is there really no simple solution for this?

    No.  The mechanism that selects an outbound interface to use looks only at the destination address.  It doesn't care about the source address, and has absolutely no concept that this packet is "in response to" some other packet that may have once passed this way.

    LVL 1

    Author Comment

    Thanks for the replies, and I'm sorry for the delay. I didn't ever solve this problem (due to what you said - IP doesn't care where it came from) so I gave up. :(

    But thanks for the help.


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