Solved: Unable to add Loopback interface

mahesh18 · ‎11-13-2011

Hi all,

i am trying to add loopback interface 0 and asisgn it IP address here is issue

2620Router(config-if)# ip address 172.16.0.0 255.55.0.0

Bad mask 0xFF370000 for address 172.16.0.0

How can i fix this?

Thanks

Mahesh

Reza Sharifi · ‎11-13-2011

Hi Mahesh,

172.16.0.0/16 is a network/subnet You need to assign a host address to the interface

try this:

interface Loopback0

ip address 172.16.1.1 255.255.255.255

HTH

View solution in original post

cadet alain · ‎11-13-2011

Hi,

your IP didn't work because:

1) it was not a host IP address but a network or subnet IP

AND

2) your mask was incorrect: 255.55.0.0 it should have been 255.255.0.0 because in a mask you must have contiguous bits

which is not the case in 55( 00110111) and the message was giving you your wrong mask in hex representation

0xFF370000 is 255.55.0.0 in dotted decimal.

Provided point 1 was corrected you could have put any valid mask for a subnet in which the IP was included like a /24 for example. But it's best practice and in some cases mandatory like in MPLS VPNs to give loopbacks a /32 mask.

Regards.

Alain

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