Re: IPv6 nexthop for IPv4

["Bjørnar Ness" <bjornar.ness@gmail.com>]

2015-03-26 15:29 GMT+01:00 Sowmini Varadhan <sowmini05@gmail.com>:
> On Thu, Mar 26, 2015 at 9:16 AM, Bjørnar Ness <bjornar.ness@gmail.com> wrote:
>> Hello, hope this is the right place to ask.
>>
>> Does anyone know if there is work beeing done in natively supporting
>> IPv6 nexthops for IPv4?
>
> What problem are you trying to solve? Do you want to tunnel your
> ipv4 packet through IPv6? there are a number of tunneling mechanisms
> in linux for this.

No, no tunneling, just route the packet directly as-is to the ipv6 nexthop

>> I know that "some" Linux switch software company is working on this, but
>> I am afraid the functionality will be more of a "hack".
>>
>> The benefit of this is stateless configuration (rfc5549), using IPv6 link-local
>> neighbor address as IPv4 nexthop, beeing able to do for example:
>>
>> ip route add 10.0.0.0/16 via fe80::225:90ff:fed3:bfb4/64 dev sfp0
>
> Trying to understand what the desired behavior is, for the route
> above: if I send a packet from 10.0.0.1 to 10.0.0.2, you want the dst-mac
> to be the mac address of e80::225:90ff:fed3:bfb4???

Absolutely, correct.

> how do you know that fe80::225:90ff:fed3:bfb4 supports ipv4
> forwarding on the receiving interface (and if it does, why didn't it
> advertise itself as an IPv4 router on that interface)?

Basically because you either added the route manually, or it was provided
by fe80::225:90ff:fed3:bfb4 itself via some routing protocol (MP-BGP)

This will be the same as any other route. How do you know it forwards traffic..

In large routed setups, address management in general and lack of IPv4 addresses
can become a big hassle. Beeing able to get a ipv6 neighbor for a ipv4
route would
make this process a lot simpler.

-- 
Bj(/)rnar