Subject: [pim] Fwd: New Version Notification for draft-taylor-pim-v4v6-translation-00.txt

From: Tom Taylor <[email-masked]>
Date: Sun, 04 Mar 2012 12:58:58 -0500

We have submitted this document dealing with one aspect of multicast 
transition. Comments are welcome.

Tom Taylor

-------- Original Message --------
Subject: New Version Notification for 
draft-taylor-pim-v4v6-translation-00.txt
Date: Sun, 04 Mar 2012 09:48:09 -0800
From: [email-masked]
To: [email-masked]
CC: [email-masked]

A new version of I-D, draft-taylor-pim-v4v6-translation-00.txt has been 
successfully submitted by Tom Taylor and posted to the IETF repository.

Filename:	 draft-taylor-pim-v4v6-translation
Revision:	 00
Title:		 A Translator For Protocol Independent Multicast (PIM) 
Interworking Between IPv4 and IPv6
Creation date:	 2012-03-04
WG ID:		 Individual Submission
Number of pages: 7

Abstract:
    This document describes the requirements and methodology for a
    translator operating within a dual stack multicast router, allowing
    it to interoperate between Protocol Independent Multicast - Sparse
    Mode (PIM-SM, RFC 4601) with IPv4 and PIM with IPv6.

The IETF Secretariat

---

From: Simon Perreault <[email-masked]>
Date: Mon, 05 Mar 2012 13:27:11 -0500

> transition. Comments are welcome.

Here are some comments...

1. The abstract says:

    This document describes the requirements and methodology ...

Shouldn't requirements be discussed in the overview/framework document 
instead of here?

2. Section 2 says:

    This specification assumes that
    each interface of the subject router is configured to use either IPv4
    or IPv6 but not both.  An exception is allowed for interfaces
    connecting only to other dual stack PIM routers implementing this
    specification.

That's a big assumption. I'm not sure it will be acceptable in practice.

Would it be possible instead to consider a dual-stack PIM router as 
being made of two logical single-stack PIM routers? We have something 
like this in our IGMP/MLD translation draft.
http://tools.ietf.org/html/draft-perreault-mboned-igmp-mld-translation-00#section-3.1

3. Section 3 says:

    Multicast group addresses SHOULD be mapped between IPv4 and IPv6 as
    described in [I-D.mboned-64-multicast-address-format].

Why SHOULD instead of MUST?

4. Section 3 says:

    If the IPv6 group
    address does not match the specified format, or if a conforming
    router is otherwise configured, mapping from IPv6 to IPv4 group
    addresses MUST use a statically-configured table.

How about MAY instead of MUST? And how about allowing any other 
mechanism an implementation may wish to use instead of limiting to 
statically-configured tables?

Simon
-- 
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From: Tom Taylor <[email-masked]>
Date: Mon, 05 Mar 2012 14:16:30 -0500

Thanks a lot for the review.

> Shouldn't requirements be discussed in the overview/framework document
[PTT] Hard to know what to call Section 2. I think it's on a different 
level from the overview, but maybe I'm wrong.
> http://tools.ietf.org/html/draft-perreault-mboned-igmp-mld-translation-00#section-3.1
[PTT] This is different from IGMP/MLD, because all the PIM routers on a 
link have to understand what the other guys are doing. When a Join is 
sent out, it affects state on all the routers, not just the one it is 
targeted to. So the assumption was as much about making PIM work in 
general as it was about translation.
> Why SHOULD instead of MUST?
[PTT] Because of the exception described further down. The IPv6 address 
might not have the right format.

[PTT] Related comment: thinking about it after I submitted the document, 
I'm not sure it's possible for two different IPv6 addresses with the 
same embedded IPv4 address to refer to different sources. More likely 
that situation would simply be a matter of the packets arriving from the 
same source through different networks. The exception would be if the 
embedded IPv4 address was shared and happened to be shared between sources.
> statically-configured tables?

[PTT] Thanks for a good alternative. Agreed.

---

From: Simon Perreault <[email-masked]>
Date: Mon, 05 Mar 2012 14:26:39 -0500

> general as it was about translation.

Now I'm more confused. PIMv4 and PIMv6 are basically "ships in the 
night", aren't they? They are not required to have the same topology. 
Are you saying that this changes with the introduction of PIM translation?

I don't know what would be the right question to ask here. I'm just very 
puzzled as to why this assumption is needed.

> might not have the right format.

Ah, right. Makes sense.

Simon

---

From: Tom Taylor <[email-masked]>
Date: Mon, 05 Mar 2012 15:41:34 -0500

Below.

> puzzled as to why this assumption is needed.
[PTT] Hmm ... I guess you're right. I'll recycle the draft before next 
week. I have too much to do to do it today.

Thanks again for your review.

...