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This Question is Not Answered 1 Correct Answer available (4 pts) 2 Helpful Answers available (2 pts)
5620 Views 5 Replies Latest reply: Sep 4, 2010 7:30 AM by Suraj Rawat RSS

Currently Being Moderated

command line confusion

Sep 3, 2010 7:34 AM

kevinlim62 129 posts since
Mar 6, 2010

What is the function/meaning of below command line?

 

!
interface FastEthernet1
ip vrf forwarding mgmtVrf
no ip address
speed auto
duplex auto
!

  • Keith Barker - CCIE RS/Security, CISSP 5,351 posts since
    Jul 3, 2009
    Currently Being Moderated
    1. Sep 3, 2010 7:48 AM (in response to kevinlim62)
    Re: command line confusion

    That command assigns that interface to a VRF (virtual routing and forwarding instance).

     

    Here is a short video that expains how a VRF works, along with a demonstration.


     

    Best wishes,

     

    Keith

  • Keith Barker - CCIE RS/Security, CISSP 5,351 posts since
    Jul 3, 2009
    Currently Being Moderated
    3. Sep 3, 2010 9:02 AM (in response to kevinlim62)
    Re: command line confusion

    it is below command line we use for the management port to recover the switch?

     

    interface FastEthernet1
    ip vrf forwarding mgmtVrf
    no ip address
    speed auto
    duplex auto

     

    There is a VRF on this router named mgmtVrf.

     

    This port has been assigned to this vrf, so that it's routing information is completely separate from the global routing table on the router.  ( I noticed there is no IP address on this interface, which makes this interface not very useful at the moment).

     

    This is not a bad idea for management interfaces, where separation is desired for production transit traffic and management traffic.

     

    Keith

  • Suraj Rawat 66 posts since
    Jun 11, 2010

    hi keith..

     

    I don't understand that how not ip-address to the interface separates the management traffic with the general traffic..

     

    I mean we have to give them some IP-add..

     

     

    regards

    Suraj..

  • Keith Barker - CCIE RS/Security, CISSP 5,351 posts since
    Jul 3, 2009
    Currently Being Moderated
    5. Sep 4, 2010 7:39 AM (in response to Suraj Rawat)
    Re: command line confusion

    hi keith..

     

    I don't understand that how not ip-address to the interface separates the management traffic with the general traffic..

     

    I mean we have to give them some IP-add..

     

     

    regards

    Suraj..

     

    Hello Suraj-

     

    Yes, you are right.

     

    This interface is assigned to a VRF, and the interface has no ip address, and is not using IP unnumbered.   This interface is not being used for L3 anything.   It is possible that there are sub interfaces that exist, and those sub interfaces may or may not be assigned to the VRF, but in short, this physical interface without an IP address is not being used.  We would need to add an IP to this interface for it to be useful.

     

    Keith

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