Subject: [Bier] Mail regarding draft-ietf-bier-mpls-encapsulation

From: Gregory Mirsky <[email-masked]>
Date: Tue, 25 Aug 2015 01:19:53 +0000

Dear Authors,
I'm concerned with the last paragraph of the Section 2:
   The BFR MUST perform the MPLS TTL processing correctly.  If the
   packet is forwarded to one or more BFR adjacencies, the BIER-MPLS
   label carried by the forwarded packet MUST have a TTL field whose
   value is one less than that of the incoming TTL.  (Of course, if the
   incoming TTL is 1, the packet will not be forwarded at all, but will
   be discarded as an MPLS packet whose TTL has been exceeded.)
I think that the last sentence, in the brackets, must require dropping BIER packets on egress if TTL is 0 and allow passing BIER packets with TTL equal 1 to other layer for processing, e.g. BIER Ping/Traceroute. Perhaps the following can be used as the last sentence:
Of course, the packet MUST NOT be forwarded if egress TTL of a labeled packet is 0. The packet MAY be discarded or passed to other layer for processing, e.g. BIER Traceroute.

                Regards,
                                Greg

---

From: Eric C Rosen <[email-masked]>
Date: Thu, 27 Aug 2015 10:52:09 -0400

Greg,

How about the following:

    The BFR MUST perform the MPLS TTL processing correctly.  If the
    packet is forwarded to one or more BFR adjacencies, the BIER-MPLS
    label carried by the forwarded packet MUST have a TTL field whose
    value is one less than that of the incoming TTL.

    Of course, if the incoming TTL is 1, the packet MUST be treated as a
    packet whose TTL has been exceeded.  The packet MUST NOT be
    forwarded, but it MAY be passed to other layers for processing (e.g.,
    to cause an ICMP message to be generated, and/or to invoke BIER-
    specific traceroute procedures, and/or to invoke other OAM
    procedures.)

Eric

On 8/24/2015 9:19 PM, Gregory Mirsky wrote:
> Dear Authors,
>
> I’m concerned with the last paragraph of the Section 2:
>
> I think that the last sentence, in the brackets, must require dropping
> BIER packets on egress if TTL is 0 and allow passing BIER packets with
> TTL equal 1 to other layer for processing, e.g. BIER Ping/Traceroute.
> Perhaps the following can be used as the last sentence:
>
> Of course, the packet MUST NOT be forwarded if egress TTL of a labeled
> packet is 0. The packet MAY be discarded or passed to other layer for
> processing, e.g. BIER Traceroute.
>
>                  Regards,
>
>                                  Greg
>

---

From: Gregory Mirsky <[email-masked]>
Date: Thu, 27 Aug 2015 15:05:29 +0000

Hi Eric,
great, absolutely agree.

	Regards,
		Greg

-----Original Message-----
From: Eric C Rosen [mailto:[email-masked]] 
Sent: Thursday, August 27, 2015 7:52 AM
To: Gregory Mirsky
Cc: BIER ([email-masked])
Subject: Re: Mail regarding draft-ietf-bier-mpls-encapsulation

Greg,

How about the following:

Eric