3750 null0

Answered Question
Mar 29th, 2007
User Badges:
  • Blue, 1500 points or more

Hi,


I created a null0 interface in 3750, I can't see the interface in the "sh run" but I'm able to route RFC 1918 to it.


Is this normal?


TIA

Correct Answer by Jon Marshall about 10 years 3 months ago

Hi


I believe it is. I have just tried creating a null0 interface in our lab on


3550

3560

6509

2621

7206VXR


None of them showed up in config. i believe this is because it is a pseudo-interface similar to /dev/null in unix. You can always add routes that point to Null0 and the IOS will do the right thing and blackhole them.


You can also do a limited amount of config on the null0 interface but it won't take an ip address etc.


HTH


Jon


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Correct Answer
Jon Marshall Fri, 03/30/2007 - 00:08
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Hi


I believe it is. I have just tried creating a null0 interface in our lab on


3550

3560

6509

2621

7206VXR


None of them showed up in config. i believe this is because it is a pseudo-interface similar to /dev/null in unix. You can always add routes that point to Null0 and the IOS will do the right thing and blackhole them.


You can also do a limited amount of config on the null0 interface but it won't take an ip address etc.


HTH


Jon


Danilo Dy Fri, 03/30/2007 - 00:12
User Badges:
  • Blue, 1500 points or more

Hi Jon,


Thanks for confirmation.


In 7500 series routers with IOS 12.1, the null0 intrerface is visible in the config.


Regards,

Dandy

Actions

This Discussion