Tunnel Interface /32 Host Mask

[johnlloyd_13]

hi all,

first, i would like to greet everyone a prosperous 2013!

i'm currently doing GRE tunneling between 2 routers and would like to use a /32 host mask, but was rejected. is this an IOS restriction?

R1(config-if)#tunnel destination 192.168.0.2

R1(config-if)#ip address 10.0.0.1 255.255.255.255

Bad mask /32 for address 10.0.0.1

R1(config-if)#ip address 10.0.0.1 255.255.255.254

R1(config-if)# do sh run int tu0

Building configuration...

Current configuration : 121 bytes

!

interface Tunnel0

ip address 10.0.0.1 255.255.255.254

tunnel source 192.168.0.1

tunnel destination 192.168.0.2

end

[Nagendra Kumar Nainar · Accepted solution]

Hi John,

You cannot directly configure a /32 address on tunnel (or other physical interface). You need to configure it on a loopback interface and assign it as "ip unnumbered loop<>" under tunnel interface as below,

!

interface Loopback3

ip address 10.3.3.3 255.255.255.255

!

interface Tunnel3

ip unnumbered Loopback3

HTH,

Nagendra

[johnlloyd_13]

hi nagendra,

thanks for the quick reply! do you have a useful link with this info?

[Hardik Vaidh]

Dear john

you cannt configure any ip directly in your tunnel or any where related to interface matter.

you have to configure interface lokback 0

ip add 10.10.10.10 255.255.255.255

no shut

show ip int brie

lookback up

then you can configure any whare 10.10.10.10 255.255.255.255

subnet 255.255.255.255 means host

[chetankottapalli]

please help me when i am configuring  the R2(config)#int Fa0/1 

ip address 3.3.3.3 255.255.255.255

i am getting the Bad mask /32 for address 3.3.3.3