Subject: [mpls] Q about IPv4-mapped IPv6 address & MPLS

From: "Rajiv Asati (rajiva)" <[email-masked]>
Date: Thu, 1 May 2014 06:08:51 +0000

We need your guidance on handling v4-mapped v6 addresses (section 2.5.5.2
of [RFC4291]). 

1. Should/Would they appear in IPv6 routing table?
2. Should an IPv6 packet with ::FFFF:127.0.0.0  be forwarded or dropped or
treated as a loopback packet, if ever received?

The answer to Q#1 will help MPLS WG to decide the proper handling of
v4-mapped v6 addresses in LDPv6 draft section 7 1st para.
http://tools.ietf.org/html/draft-ietf-mpls-ldp-ipv6-12#section-7 *

The answer to Q2 will help us assess the efficacy of RFC4379.

Thanks. 
-- 
Cheers,
Rajiv 

* //
An LSR MUST treat the IPv4-mapped IPv6 address, defined in
section 2.5.5.2 of [RFC4291], the same as that of a global IPv6 address
and not mix it with the 'corresponding' IPv4 address.
//

---

From: Mikael Abrahamsson <[email-masked]>
Date: Thu, 1 May 2014 08:40:01 +0200 (CEST)

> The answer to Q2 will help us assess the efficacy of RFC4379.

http://tools.ietf.org/html/draft-itojun-v6ops-v4mapped-harmful-02

I realise this draft seems to have died, but I would never expect to see 
packets with these addresses on the wire or in the routing table and if 
they're there, I would want hosts/routers to drop them. Not doing this 
seems to me it would open to all kinds of unwanted consequences when it 
comes to filtering etc.

-- 
Mikael Abrahamsson    email: [email-masked]

---

From: Mikael Abrahamsson <[email-masked]>
Date: Thu, 1 May 2014 08:59:22 +0200 (CEST)

On Thu, 1 May 2014, Hesham Soliman wrote:

>> or in the routing table
>
> => That¹s a different story. I don¹t think there is anything banning this,
> not least due to the fact that it is an implementation issue. If that
> entry points to an IPv4 tunnel it should be fine. So it is possible to
> implement a tunnel that way inside the host/router and nothing to stop
> someone from doing unless I missed an RFC.

Let me qualify my statement that I don't want to see it outside the box, 
ie in routes it's sending to anyone else. If it's in the internal RIB I 
have no problem with it, if it starts being announced in IGP and BGP then 
I think it's a bigger issue.

>> and if
>> they're there, I would want hosts/routers to drop them.
>
> => Is that behaviour documented somewhere? Also, you¹re mixing them
> appearing on the wire with an internal implementation issue.

If this is documented somewhere, I am not aware, but I am definitely not 
the right person to ask about what might be in what RFC.