Re: [bess] Question regarding RFC6625 and this draft-->//RE: I-D Action: draft-ietf-bess-mvpn-expl-track-13.txt

[Xiejingrong <[e-mail]>]

Hi Jeffrey,

Thanks for the explaination.
I have the same understanding "the text in RFC6625 is really/mainly about which tunnel to send/receive on in a steady state."
What confusing me is the "which tunnel to receive" decision, obviously on receiver site PE.

In my opinion, the receiver site PE should not do the decision, but be prepared to *any possible tunnel* that will be used by the sender site PE for a specific (S,G) flow.
Even in a steady state the sender site PE are using the (S,G) PMSI-tunnel for a (S,G) flow, the preparation on the (*,*)PMSI-tunnel should be kept on the receiver site PE.

Below is the errata report I have raised, and I hope it can be clarified.
https://www.rfc-editor.org/errata/eid5605


-----Original Message-----
From: Jeffrey (Zhaohui) Zhang [mailto:[e-mail]] 
Sent: Thursday, January 24, 2019 12:32 AM
To: Xiejingrong <[e-mail]>; [e-mail]
Cc: [e-mail]
Subject: RE: Question regarding RFC6625 and this draft-->//RE: [bess] I-D Action: draft-ietf-bess-mvpn-expl-track-13.txt

Hi Jingrong,

You're right that to avoid disruption and duplication a switchover delay is needed on the source PE and desired on the receiver PE, and that means the forwarding state needs to accommodate that.

However, the text is in RFC6625 is really/mainly about which tunnel to send/receive on in a steady state. That's not explicitly spelled out, but that's the intention per my understanding.

To be more accurate, the text is about which PMSI route to match. In theory a PMSI can be instantiated with one particular tunnel at one time and then switch to another tunnel. In that case the PMSI route is updated with a different PTA - the match to sending/receiving does not change yet the switchover delay referred to RFC6513 still applies.

Jeffrey

> -----Original Message-----
> From: Xiejingrong [mailto:[e-mail]]
> Sent: Tuesday, January 22, 2019 8:47 PM
> To: Jeffrey (Zhaohui) Zhang <[e-mail]>; 
> draft-ietf-bess-mvpn-expl- [e-mail]
> Cc: [e-mail]
> Subject: RE: Question regarding RFC6625 and this draft-->//RE: [bess] 
> I-D
> Action: draft-ietf-bess-mvpn-expl-track-13.txt
> 
> Hi Jeffrey,
> 
> The sender PE need to work on (*,*) tunnel for a while (switch-over 
> timer) and then switch to the (S,G) tunnel.
> 
> To quote RFC6513 section 7.1.1
>    The decision to bind a particular C-flow (designated as (C-S,C-G)) to
>    a particular P-tunnel, or to switch a particular C-flow to a
>    particular P-tunnel, is always made by the PE that is to transmit the
>    C-flow onto the P-tunnel.
> 
>    When a C-flow is switched from one P-tunnel to another, the purpose
>    of running a switch-over timer is to minimize packet loss without
>    introducing packet duplication.
> 
> Jingrong
> 
> -----Original Message-----
> From: Jeffrey (Zhaohui) Zhang [mailto:[e-mail]]
> Sent: Saturday, January 12, 2019 3:29 AM
> To: Xiejingrong <[e-mail]>; draft-ietf-bess-mvpn-expl- 
> [e-mail]
> Cc: [e-mail]
> Subject: RE: Question regarding RFC6625 and this draft-->//RE: [bess] 
> I-D
> Action: draft-ietf-bess-mvpn-expl-track-13.txt
> 
> Jingrong,
> 
> > It is determined by the sender site PE whether to steer the flow of 
> > (C-S, C-G)
> into (*,*) PMSI-tunnel or (S,G)PMSI-tunnel, and the receiver site PE 
> should work correctly in any case.
> 
> Why would the sender PE send into (*, *) when there is a match for (S,G)?
> 
> Jeffrey
> 
> > -----Original Message-----
> > From: Xiejingrong [mailto:[e-mail]]
> > Sent: Thursday, January 10, 2019 11:10 PM
> > To: [e-mail]
> > Cc: [e-mail]
> > Subject: Question regarding RFC6625 and this draft-->//RE: [bess] I-D Action:
> > draft-ietf-bess-mvpn-expl-track-13.txt
> >
> > Hi,
> >
> > I have a question regarding RFC6625 and this draft, since this draft 
> > is based on the RFC6625.
> >
> > In RFC6625 section "3.2.1 Finding the match for (C-S,C-G) for Data
> > Reception":
> > It defined the rules for Finding the matched S-PMSI A-D route for a
> > (C-S,C-G) state on a receiver site PE.
> > It seems to me that, the receiver site PE will respond only to the
> > *ONE* 'Match for Reception' S-PMSI A-D route, and setup the 
> > 'reception state' only for the 'Matched' S-PMSI A-D route.
> > But it is not true for an inclusive-selective relation between 
> > S-PMSI A-D (*,*) and S-PMSI A-D(S,G).
> > Thinking the S-PMSI A-D (*,*) as an Inclusive one, the receiver site 
> > PE with a
> > (C-S,C-G) state should keep its join state on both the S-PMSI A-D
> > (*,*) and S- PMSI A-D(S,G), and setup the 'reception state' on both 
> > the (*,*) PMSI-tunnel and (S,G) PMSI-tunnel.
> > It is determined by the sender site PE whether to steer the flow of 
> > (C-S, C-G) into (*,*) PMSI-tunnel or (S,G)PMSI-tunnel, and the 
> > receiver site PE should work correctly in any case.
> >
> > My question:
> > Is the section 3.2.1 or RFC6625 wrong and should the 'Match for Reception'
> > include *one or many* S-PMSI A-D routes ?
> > Is it a problem that can affect this draft ?
> >
> > Thanks
> > Jingrong.
> >
> >
> > -----Original Message-----
> > From: BESS [mailto:[e-mail]] On Behalf Of internet- 
> > [e-mail]
> > Sent: Thursday, November 29, 2018 12:27 AM
> > To: [e-mail]
> > Cc: [e-mail]
> > Subject: [bess] I-D Action: draft-ietf-bess-mvpn-expl-track-13.txt
> >
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts directories.
> > This draft is a work item of the BGP Enabled ServiceS WG of the IETF.
> >
> >         Title           : Explicit Tracking with Wild Card Routes in Multicast VPN
> >         Authors         : Andrew Dolganow
> >                           Jayant Kotalwar
> >                           Eric C. Rosen
> >                           Zhaohui Zhang
> > 	Filename        : draft-ietf-bess-mvpn-expl-track-13.txt
> > 	Pages           : 21
> > 	Date            : 2018-11-28
> >
> > Abstract:
> >    The Multicast VPN (MVPN) specifications provide procedures to allow a
> >    multicast ingress node to invoke "explicit tracking" for a multicast
> >    flow or set of flows, thus learning the egress nodes for that flow or
> >    set of flows.  However, the specifications are not completely clear
> >    about how the explicit tracking procedures work in certain scenarios.
> >    This document provides the necessary clarifications.  It also
> >    specifies a new, optimized explicit tracking procedure.  This new
> >    procedure allows an ingress node, by sending a single message, to
> >    request explicit tracking of each of a set of flows, where the set of
> >    flows is specified using a wildcard mechanism.  This document updates
> >    RFCs 6514, 6625, 7524, 7582, and 7900.
> >
> >
> > The IETF datatracker status page for this draft is:
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> > 3A__datatracker.ietf.org_doc_draft-2Dietf-2Dbess-2Dmvpn-2Dexpl-
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