Why I can't use "no" to disable settings (like in cisco)?

[horiz0n]

Hi

I've made some configuration:

vlan 3
   name "vlan 3"
   untagged A1-A20,B1-B24,C1-C24,D1-D24
   tagged A21-A22
   no ip address
   ip igmp
   ip igmp forward A1,A21-A22
   no ip igmp querier
   qos priority 3
   exit

but I would like to remove port A1 from igmp forward. I've tried to set ip igmp forward A21,A22 but it does not work, I still have A1. I've tried to disable IGMP support and turn it back again, but it remembers previous settings.

Of course the simpliest command

no ip igmp forward A1,A21-A22 gives me:

(vlan 3)# no ip igmp forward A1,A21-A22
Invalid input: forward

So the only one way to fix that is download config, edit in notepad and then upload and reboot switch. I just can't believe. Of coruse there is nothng about that in manuall.

[Michael Patmon]

Hello.  In general config defaults do not get displayed in the output of "show run".  In many cases disabling the feature (or sub-feature) by prepending "no" to the command is the default, and therefore is not displayed in "show run".  For this case the default for IGMP is "auto" so setting it back to that will remove it from the config output:

vlan 3
   name "VLAN3"
   untagged 2-10
   no ip address
   ip igmp
   ip igmp forward 2-5
   exit

2920-switch(vlan-3)# ip igmp auto 2-5

vlan 3
   name "VLAN3"
   untagged 2-10
   no ip address
   ip igmp
   exit

I agree that it would be nice if there was a way to "default" a particular config item, or if "no" would always return it to default (as opposed to disable).