no keepalive up/up

| Friday, June 25th, 2010 | 9 Comments »

I learned this new trick from reading an old CCIE book. If you want to keep an interface with up/up status with no cable connected to it, especially for simulation purposes all you have to do is disable the keepalive like so:

Router#sh ip int brie
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            unassigned      YES unset  administratively down down
Serial0/0                  unassigned      YES unset  administratively down down
BRI0/0                     unassigned      YES unset  administratively down down
BRI0/0:1                   unassigned      YES unset  administratively down down
BRI0/0:2                   unassigned      YES unset  administratively down down

Router(config)#int fa0/0
Router(config-if)#no shut
00:15:26: %LINK-3-UPDOWN: Interface FastEthernet0/0, changed state to u
Router(config-if)#no keepalive
Router(config-if)#end

Router#
00:15:39: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
Router#
Router#sh ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            unassigned      YES unset  up                    up
Serial0/0                  unassigned      YES unset  administratively down down
BRI0/0                     unassigned      YES unset  administratively down down
BRI0/0:1                   unassigned      YES unset  administratively down down
BRI0/0:2                   unassigned      YES unset  administratively down down
Router#

Pretty cool huh?

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  • Josephtidwell

    Very cool! A lot better then using the rj45 loopback plug I've been using.

  • brandontek

    It's a great tip isn't it? I can't believe it actually worked. I've always thought that a port needed a physically connected layer 1 connection to get UP/UP status with proper signaling.

  • jamesleecoleman

    Sweetness!!! Thanks for sharing!!! I've been using a physical connection for all the fastethernet ports so I can practice routing.

  • Tawfik Belmekki

    awesome 😀

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  • http://twitter.com/ashubro Ashwani kumar

    :)

  • http://twitter.com/ashubro Ashwani kumar

    i dont know about real router but i only use GNS3 for my study and in my 3700 series router if i issue no shut command even without connecting with any device it stays at up/up state no need to use no keepalives command :)

  • http://www.brandontek.com admin

    Yes, this is true but I believe this to be a bug with GNS3. This can be misleading and send an engineer in the wrong direction in terms of troubleshooting…..