Re: [mpls] p2mp BFD over MPLS LSP

Gyan Mishra <> Wed, 17 October 2018 14:58 UTC

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From: Gyan Mishra <>
Date: Wed, 17 Oct 2018 10:58:22 -0400
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To: Greg Mirsky <>
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Subject: Re: [mpls] p2mp BFD over MPLS LSP
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Thanks Greg for the thorough explanation.

P2MP BFD over mpls lsp so that could be mldp or TE p2mp lsp correct and for
either if protection is done at the head of the lsp which would be the FEC
root you would not need the P2MP bfd with active tail spec.

Thank you



On Mon, Oct 15, 2018, 10:44 AM Greg Mirsky <> wrote:

> Hi Gyan,
> thank you for your very pointed question. The base specification for BFD
> in multipoint networks (often referred to as "p2mp BFD") explains that in
> p2mp and mp2mp MPLS LSP cases p2mp BFD MAY use IP/UDP encapsulation in
> Section 5.8:
>    For multipoint LSPs, when IP/UDP encapsulation of BFD control packets
>    is used, MultipointTail MUST expect destination UDP port 3784.
>    Destination IP address of BFD control packet MUST be in
>    range for IPv4 or in 0:0:0:0:0:FFFF:7F00:0/104 range for IPv6.  The
>    use of these destination addresses is consistent with the
>    explanations and usage in [RFC8029].  Packets identified as BFD
>    packets MUST be consumed by MultipointTail and demultiplexed as
>    described in Section 5.13.2.  Use of other types of encapsulation of
>    the BFD control message over multipoint LSP is outside the scope of
>    this document.
> In some environments using IP/UDP encapsulation for BFD Control packet is
> overburden, and this draft explains how p2mp BFD must be used with G-ACh
> encapsulation. Both types, IP/UDP and G-ACh, may be used to monitor MVPN.
> Additionally, note that the base p2mp BFD mode does not support tail
> notification of the path failure to the head. If the protection action to
> be performed not by the tail but the head, you'd need to use BFD for
> Multipoint Networks with Active Tail specification. G-ACh encapsulation may
> be used in any of these specs.
> Regards,
> Greg
> On Sat, Oct 13, 2018 at 7:14 PM Gyan Mishra <> wrote:
>> Hi Greg
>> So this Draft would support BFD with IPv6 encap along with the IPV4 encap
>> for P2MP MVPN LSP so would this support all MVPN profiles.
>> Thank you
>> Gyan
>> On Sat, Oct 13, 2018, 4:25 PM Greg Mirsky <> wrote:
>>> Dear WG Chairs, et al.,
>>> as the author of the BFD for Multipoint Networks over
>>> Point-to-Multi-Point MPLS LSP (draft-mirsky-mpls-p2mp-bfd) I would like to
>>> ask you to consider WG adoption call of the draft. The document addresses
>>> non-IP encapsulation of p2mp BFD over MPLS LSP that may be useful if the
>>> overhead of IP, particularly IPv6, encapsulation is the concern. The base
>>> specification of BFD for Multipoint Networks is at this time in IESG LC.
>>> Regards,
>>> Greg
>>> _______________________________________________
>>> mpls mailing list