Subject: [pcp] PCP Draft 29 question about PREFER_FAILURE and Suggested External Address field of all zeroes

From: Norman Sardella <[email-masked]>
Date: Thu, 14 Feb 2013 14:53:25 -0500

In draft-ietf-pcp-base-29,
  "Section 13.2.  PREFER_FAILURE Option for MAP Opcode",
The draft mentions that when PREFER_FAILURE is set,
   "all-zeros IPv4 or all-zeros IPv6 address in the Suggested External
    Address field, it is invalid."

Is this a valid case? Its unclear in a CGNAT/DS-LITE environment
where the CPE would be running a UPnP to PCP gateway and the CGNAT
equipment provides an External Address, how the CPE could provide an 
initial PCP MAP request with an External IP Address when the CGNAT 
device maintains them.  On a MAPPING update, I could see providing an
Suggested External Address

I understand that UPnP IGDv1 client allows to dictate
mapping a specific port, but its unclear in a CGNAT/DS-LITE environment
how to specify an Suggested External IP address.

On a MAPPING update, I could see providing an Suggested External
Address, but don't understand how a CPE provide the Suggested External
Address on an initial MAP request.

> 13.2.  PREFER_FAILURE Option for MAP Opcode
...
>
>    If a PCP request contains the PREFER_FAILURE option and has zero in
>    the Suggested External Port field, or has the all-zeros IPv4 or all-
>    zeros IPv6 address in the Suggested External Address field, it is
>    invalid.  The PCP server MUST reject such a message with the
>    MALFORMED_OPTION error code.

---

From: "Dan Wing" <[email-masked]>
Date: Thu, 14 Feb 2013 14:21:18 -0800

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
> Norman Sardella
> Sent: Thursday, February 14, 2013 11:53 AM
> To: [email-masked]
> Subject: [pcp] PCP Draft 29 question about PREFER_FAILURE and Suggested
> External Address field of all zeroes
> 
>   "Section 13.2.  PREFER_FAILURE Option for MAP Opcode", The draft
> mentions that when PREFER_FAILURE is set,
> Is this a valid case? Its unclear in a CGNAT/DS-LITE environment where
> the CPE would be running a UPnP to PCP gateway and the CGNAT equipment
> provides an External Address, how the CPE could provide an initial PCP
> MAP request with an External IP Address when the CGNAT device maintains
> them.

The draft says:

   invalid.

I believe it should say:

   If a PCP request contains the PREFER_FAILURE option and has zero in
   the Suggested External Port field, or has the all-zeros IPv4 or all-
......................................^^
                                     "and"
   zeros IPv6 address in the Suggested External Address field, it is
   invalid.

http://tools.ietf.org/html/draft-ietf-pcp-upnp-igd-interworking is the
canonical document explaining the interworking function, which doesn't
go into that level of detail.

Would that fix the problem?

-d

> Address
> I understand that UPnP IGDv1 client allows to dictate mapping a specific
> port, but its unclear in a CGNAT/DS-LITE environment how to specify an
> Suggested External IP address.
> 
> 
> _______________________________________________
> pcp mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/pcp

---

From: Norman Sardella <[email-masked]>
Date: Fri, 15 Feb 2013 08:15:57 -0500

Yes, I'm good with that.

Thanks