Reg- IPv6 and IPv4 configuration on LAN interface

[#1]

Hi,

I need help regarding Ipv4 and IPv6 configuration on LAN interface the config is below-

interface GigabitEthernet0/0/0
description LAN
ip address 10.136.217.1 255.255.255.128
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip pim sparse-mode
ip verify unicast source reachable-via rx
negotiation auto
ipv6 address 2001:4408:8026:2::1/64
ipv6 enable

The poblem is user conneted to LAN are browsing internet via IPv6 ip's not by IPv4 ip's which is natted with ipv4 public IP. I want user to go internet via IPv4 ip's and secondary by IPv6 IP.

Thanks

[Julio E. Moisa]

Hi

Is the user obtaining an IPv4 address via DHCP? is the DHCP configured locally?

[#3]

No user are not obtaining ipv4 address via DHCP as you can see in the cofiguration-

interface GigabitEthernet0/0/0
description LAN
ip address 10.136.217.1 255.255.255.128
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip pim sparse-mode
ip verify unicast source reachable-via rx
negotiation auto
ipv6 address 2001:4408:8026:2::1/64
ipv6 enable

As john told windows  prefers ipv6 over ipv4 if ipv6 connectivity is available i want some command on my LAN interface to prefer IPV4 over IPv6.

Thanks

[johnd2310]

HI,

Assuming your users are using windows clients, then the reason you are seeing this behavior is because windows  prefers ipv6 over ipv6 if ipv6 connectivity is available. If you run the following command on a window client: netsh interface ipv6 show prefixpolicies, you should see something similar to the following:

Querying active state...

Precedence Label Prefix
---------- ----- --------------------------------
50 0 ::1/128
40 1 ::/0
30 2 2002::/16
20 3 ::/96
10 4 ::ffff:0:0/96
5 5 2001::/32

The ipv6 addresses (::/0) have higher preference to the ipv4 address (::96,::ffff:0:0/96)

you can change the prefix policy to make ipv4 the default using the set prefixpolicy command.

Is there any particular reason you prefer ipv4 over ipv6?

Thanks

John

[#5]

Hi John,

Thanks for the reply, actually we are in testing phase and our other devices are not ipv6 enabel. As you have suggested to change prefix policy to make ipv4 the default using the set prefixpolicy,

but i want some command on router LAN interface to make IPv4 default and IPV6 secondary.

Thanks

[johnd2310]

Hi,

I don't think you will be able to do this on the router. You can only change ipv4/ipv6 preference  on the client.

Thanks

John