Getting Bad masks on sub-interfaces?

MrXpert

I've been trying to configure IP addresses on the sub-interfaces on a router. This is for the purpose of setting up a router on a stick. I've done it many times before and it works fine but this time around I thought i'd try it with VLSM in mind which i have only recently read about (actually watched via cbt nuggets). Somewhere I am clearly going wrong. On my first attempt at trying to set the IP address for a sub interface I got a bad mask error message

Here's some output I got from the command entered on the router

NOTTS-R1(config)#int fa0/0.250

%LINK-5-CHANGED: Interface FastEthernet0/0.250, changed state to up

%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0.250, changed state to up
NOTTS-R1(config-subif)#
NOTTS-R1(config-subif)#encap
NOTTS-R1(config-subif)#encapsulation dot1q 250 ?
native Make this as native vlan
<cr>
NOTTS-R1(config-subif)#encapsulation dot1q 250
NOTTS-R1(config-subif)#ip address 172.16.1.0 255.255.255.240
Bad mask /28 for address 172.16.1.0

I then also tried it on the normal fa0/0 interface

NOTTS-R1(config)#int fa0/0
NOTTS-R1(config-if)#ip address 172.16.0.0 255.255.255.128
Bad mask /25 for address 172.16.0.0

It's probably something abvious I am missing or just not seeing.Anyone help me please?

ColbyG

You're trying to assign an address to the NID. Make it .1, not .0.

johnwest43

The only way you can use .0 is with a mask of 255.255.255.254

ColbyG

johnwest43 wrote: »

The only way you can use .0 is with a mask of 255.255.255.254

How about 192.168.1.0/23?

MrXpert

lol what a wally I am.
Thanks, sorted. Sometimes i'd swear i'd forget to put socks on in the morning before going out

cisco_trooper

ColbyG wrote: »

How about 192.168.1.0/23?

Yep. I assigned something an IP address of A.B.C.0/23 not too long ago. People looked at me like I was retarded.