Subject: [pim] Batch of Errata on RFC 5496

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 17 Sep 2013 22:24:52 +0100

Hi,

Bharat had a spurt of enthusiasm back in June and raised some Errata against RFC
5496. I have addressed most of them, but need your help with one.

http://www.rfc-editor.org/errata_search.php?eid=3665 suggests that the RPF
Vector TLV always contains the address of an edge router.

In reading Section 3.1 of RFC 5496, I am unable to tell whether the intention
was to say:

1. it could be an RP or root you are trying to reach through an edge router

or

2. you could direct the traffic direct to an edge router (in or attached to the
core)

or

3. both

To me, the text says 2. The Errata says 1.

I need help to resolve this.

Thanks,
Adrian

---

From: Stig Venaas <[email-masked]>
Date: Tue, 17 Sep 2013 14:48:46 -0700

Hi

> 5496. I have addressed most of them, but need your help with one.

I agree with Bharat.

> To me, the text says 2. The Errata says 1.

I think the RFC says 1 while the errata is correct and says 2.

For source trees the attribute is used to specify an edge router for
RPF instead of the source.

For shared trees it is exactly the same, except the RP address is used
instead of the source address. Hence the attribute is used to specify
an edge router for RPF instead of the RP address.

So I think he is right. I hope the authors will correct me if they
disagree.

Stig

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---

From: "Adrian Farrel" <[email-masked]>
Date: Tue, 17 Sep 2013 23:16:55 +0100

Thanks Stig and oops.
You correctly spotted I have my 1 and 2 the wrong way around.

A

> -----Original Message-----
> From: Stig Venaas [mailto:[email-masked]]
> Sent: 17 September 2013 22:49
> To: [email-masked]
> Cc: [email-masked]; [email-masked]; [email-masked];
> [email-masked]; [email-masked]
> Subject: Re: [pim] Batch of Errata on RFC 5496
> 
> Hi
>

---

From: Eric Rosen <[email-masked]>
Date: Wed, 18 Sep 2013 11:13:15 -0400

Stig> I think the RFC says 1 while the errata is correct and says 2.

Stig> For source trees the attribute is used to specify an edge router for
Stig> RPF instead of the source.

Stig> For shared trees it is exactly the same, except the RP address is used
Stig> instead of the source address. Hence the attribute is used to specify
Stig> an edge router for RPF instead of the RP address.

I agree.  Perhaps the text in 3.1

        "In this case, the RPF Vector TLV contains the IP address of a
        Rendezvous Point (RP)."

should be:

        "In this case, 'Edge 1' must be on the path to the RP."

BTW, it would be helpful if the subject line mentioned the title of the RFC,
as the RFC authors do not necessarily remember the RFC numbers of all the
RFCs they've written.