Thief MAC ADDRESS

Discussion in 'Cisco' started by ns, Mar 3, 2005.

  1. ns

    ns Guest

    Hi all,

    I have two cisco routers and one windows server. All is connected to the
    catalyst 4006 (L3 Router) :

    ROUTER_A
    SERVER_A
    ROUTER_Z
    SWITCH_4006

    When SERVER_A need to talk with ROUTER_A via SWITCH_4006. The SWITCH_4006
    receive ARP response from ROUTER_Z talking that the MAC address of SERVER_A
    is his MAC address !!! why !!???

    I confirme that each network interface has it MAC address !!

    So, bad mac address is allocated on the SWITCH_4006.
    On the same time, i can see on the SWITCH_4006 the real MAC address of
    ROUTER_Z !!

    So, this problem cause packet lost between SERVER_A and ROUTER_A

    Can you help me please !!???

    ThankYou very mych.

    Best Regards
    NS
    ns, Mar 3, 2005
    #1
    1. Advertising

  2. "ns" <> wrote in message news:...
    > I have two cisco routers and one windows server. All is connected to the
    > catalyst 4006 (L3 Router) :
    >
    > ROUTER_A
    > SERVER_A
    > ROUTER_Z
    > SWITCH_4006
    >
    > When SERVER_A need to talk with ROUTER_A via SWITCH_4006. The SWITCH_4006
    > receive ARP response from ROUTER_Z talking that the MAC address of
    > SERVER_A
    > is his MAC address !!! why !!???


    Typically, this happens when the subnet mask is set incorrect on the router
    inteface, or there are mismatched secondary addresses. A router will
    respond with its MAC address in proxy for an IP address. If it receives an
    ARP request for a device on another interface, it will answer that ARP in
    order to facilitate routing.

    You can turn it off:

    interface (mumble)
    no ip proxy-arp

    But, if the reply is happening, you probably have some kind of address/mask
    mixup, or an interface plugged into the wrong LAN or VLAN.


    Need more details, like configuration....
    Phillip Remaker, Mar 3, 2005
    #2
    1. Advertising

  3. ns

    ns Guest

    Hi all,

    - The subnet mask is correct

    - I don't have secondary address on the router but i have two FastEthernet
    interfaces. The router is used as gateways between two physical networks.

    I will try the command "no ip proxy-arp" on the interface but i don't
    understund why the router is identified as owner of mac address searched !

    ThankYou very much Phillip for your help
    I will let you know a bout tests.

    Best Regards
    NS


    "Phillip Remaker" <> a écrit dans le message
    de news:%dIVd.2309$...
    >
    > "ns" <> wrote in message news:...
    > > I have two cisco routers and one windows server. All is connected to the
    > > catalyst 4006 (L3 Router) :
    > >
    > > ROUTER_A
    > > SERVER_A
    > > ROUTER_Z
    > > SWITCH_4006
    > >
    > > When SERVER_A need to talk with ROUTER_A via SWITCH_4006. The

    SWITCH_4006
    > > receive ARP response from ROUTER_Z talking that the MAC address of
    > > SERVER_A
    > > is his MAC address !!! why !!???

    >
    > Typically, this happens when the subnet mask is set incorrect on the

    router
    > inteface, or there are mismatched secondary addresses. A router will
    > respond with its MAC address in proxy for an IP address. If it receives

    an
    > ARP request for a device on another interface, it will answer that ARP in
    > order to facilitate routing.
    >
    > You can turn it off:
    >
    > interface (mumble)
    > no ip proxy-arp
    >
    > But, if the reply is happening, you probably have some kind of

    address/mask
    > mixup, or an interface plugged into the wrong LAN or VLAN.
    >
    >
    > Need more details, like configuration....
    >
    >
    ns, Mar 8, 2005
    #3
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. catwalker63

    OT: Thief with no clue

    catwalker63, Apr 2, 2005, in forum: MCSE
    Replies:
    0
    Views:
    444
    catwalker63
    Apr 2, 2005
  2. Ant

    To catch a Thief.

    Ant, Sep 19, 2004, in forum: Computer Support
    Replies:
    20
    Views:
    4,703
    Samuel Townsend
    Sep 21, 2004
  3. LCT

    Thief Market

    LCT, Oct 1, 2003, in forum: Digital Photography
    Replies:
    1
    Views:
    444
    George Kerby
    Oct 1, 2003
  4. DVD Verdict
    Replies:
    0
    Views:
    462
    DVD Verdict
    Sep 4, 2003
  5. ttripp
    Replies:
    5
    Views:
    2,214
    Thrill5
    Feb 5, 2010
Loading...

Share This Page