RE: New Version Notification for draft-vgovindan-mpls-extended-bfd-disc-tlv-00.txt

["Nobo Akiya (nobo)" <[e-mail]>]

Hi Greg, Prasad, et al,

> -----Original Message-----
> From: mpls [mailto:[e-mail]] On Behalf Of Gregory Mirsky
> Sent: Monday, July 07, 2014 5:29 PM
> To: Vengada Prasad Govindan (venggovi); [e-mail]
> Cc: [e-mail]
> Subject: Re: [mpls] New Version Notification for draft-vgovindan-mpls-
> extended-bfd-disc-tlv-00.txt
> 
> Hi Prasad,
> this is very interesting proposal and I think that the MPLS WG will be
> interested in the discussion. Couple comments and questions:
> • I believe that monitoring of ECMP segments on link layer is more efficient
> comparing to e2e monitoring. The document suggests otherwise. Could you
> give scenarios or use cases that support usefulness of multiple BFD sessions
> between the same peers, given that you need to control mapping of BFD
> sessions to a particular path;

A bit of a background on this document.

EVPN is very keen on wanting to use BFD per EL (or subset of the ELs) to meet their requirements. These are described in:

draft-salam-l2vpn-evpn-oam-req-frmwk
draft-vgovindan-l2vpn-evpn-bfd

With that said, I fully agree that there is going to be a huge impact to BFD scale if we are to proceed down this path, and this should be considered/discussed in a group that includes BFD folks.

Note that the format of the draft-vgovindan-mpls-extended-bfd-disc-tlv is kept generic so that multiple sessions are abstracted by "Instance Identifier" rather than boostrapped BFD sessions being strictly tied to something else (like EL value). So the draft-vgovindan-mpls-extended-bfd-disc-tlv was created as result of EVPN requirement but draft-vgovindan-mpls-extended-bfd-disc-tlv itself is a generic document.

> • another use case to support multiple BFD
> sessions between the same peers is OAM redundancy. What you see as the
> main benefit there? How to manage detection times among multiple BFD
> sessions?

How many sessions a node bootstraps for a same FEC/path to the remote node, why and how those sessions are related is a local matter. Perhaps that should be stated in the document.

> • have you looked at Section 2.2.1 of the draft-ietf-mpls-lsp-ping-mpls-tp-
> oam-conf and Section 3.3 of the draft-ietf-ccamp-rsvp-te-mpls-tp-oam-ext

Thanks for the pointer. Yes we can certainly extend those TLVs instead if that is the consensus.

The other aspect of draft-vgovindan-mpls-extended-bfd-disc-tlv that will be beneficial to get-feedback/discuss is Appendix A in the document, whether or not we are happy with implicit assumption of bootstrapped BFD session being deleted [sometime after] those sessions go down.

Thanks!

-Nobo

> 
> Regards,
>         Greg
> 
> -----Original Message-----
> From: Rtg-bfd [mailto:[e-mail]] On Behalf Of Vengada
> Prasad Govindan (venggovi)
> Sent: Friday, July 04, 2014 8:33 AM
> To: [e-mail]
> Subject: FW: New Version Notification for draft-vgovindan-mpls-extended-
> bfd-disc-tlv-00.txt
> 
> Hello all,
>   We have posted a new draft outlining a proposal to extend the BFD
> Discriminator TLV of the MPLS ping to bootstrap multiple BFD sessions for a
> <MPLS FEC, LSP> tuple. Please let us know your questions, comments,
> suggestions about this draft.
> Thanks
> Prasad
> 
> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]]
> Sent: Friday, July 04, 2014 6:41 PM
> To: Nobo Akiya (nobo); Vengada Prasad Govindan (venggovi); Nobo Akiya
> (nobo); Vengada Prasad Govindan (venggovi)
> Subject: New Version Notification for draft-vgovindan-mpls-extended-bfd-
> disc-tlv-00.txt
> 
> 
> A new version of I-D, draft-vgovindan-mpls-extended-bfd-disc-tlv-00.txt
> has been successfully submitted by Vengada Prasad Govindan and posted to
> the IETF repository.
> 
> Name:           draft-vgovindan-mpls-extended-bfd-disc-tlv
> Revision:       00
> Title:          Label Switched Path (LSP) Ping Extended Bidirectional Forwarding
> Detection (BFD) Discriminator TLV Document date:  2014-07-04
> Group:          Individual Submission
> Pages:          8
> URL:            http://www.ietf.org/internet-drafts/draft-vgovindan-mpls-
> extended-bfd-disc-tlv-00.txt
> Status:         https://datatracker.ietf.org/doc/draft-vgovindan-mpls-
> extended-bfd-disc-tlv/
> Htmlized:       http://tools.ietf.org/html/draft-vgovindan-mpls-extended-
> bfd-disc-tlv-00
> 
> 
> Abstract:
>    This document defines an extended Bidirectional Forwarding Detection
>    (BFD) discriminator TLV for the Multiprotocol Label Switching (MPLS)
>    Label Switched Path (LSP) Ping mechanism, to allow bootstrapping of
>    multiple BFD sessions for a given FEC.
> 
> 
> 
> 
> 
> Please note that it may take a couple of minutes from the time of
> submission until the htmlized version and diff are available at tools.ietf.org.
> 
> The IETF Secretariat
> 
>