Subject: 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: Christian Huitema <[email-masked]>
Date: Thu, 1 May 2014 06:44:29 +0000

> http://tools.ietf.org/html/draft-ietf-mpls-ldp-ipv6-12#section-7 *

You may want to check RFC 6052, IPv6 Addressing of IPv4/IPv6 Translators. RFC 6052 updates RFC4291, and lets translators construct domain specific addresses that can actually be used in the routing tables. It also includes an answer to your loopback packet question:

   The Well-Known Prefix MUST NOT be used to represent non-global IPv4
   addresses, such as those defined in [RFC1918] or listed in Section 3
   of [RFC5735].  Address translators MUST NOT translate packets in
   which an address is composed of the Well-Known Prefix and a non-
   global IPv4 address; they MUST drop these packets.

-- Christian Huitema

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From: Hesham Soliman <[email-masked]>
Date: Thu, 01 May 2014 16:46:33 +1000

>packets with these addresses on the wire

=> I recall an information RFC but don¹t remember the number. I agree they
will most likely not appear on the wire.

> 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.

> 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.

Hesham

>Not doing this 
>_______________________________________________
>v6ops mailing list
>[email-masked]
>https://www.ietf.org/mailman/listinfo/v6ops

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

> 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.

> 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.