Re: WGLC comments on bfd-mpls-05
Rahul Aggarwal <rahul@juniper.net> Wed, 07 May 2008 20:01 UTC
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Date: Wed, 07 May 2008 13:00:05 -0700
From: Rahul Aggarwal <rahul@juniper.net>
To: Carlos Pignataro <cpignata@cisco.com>
Subject: Re: WGLC comments on bfd-mpls-05
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References: <20080430203803.K89520@sapphire.juniper.net> <481F69CA.1020406@cisco.com> <20080505154957.M81069@sapphire.juniper.net> <4820A894.2040608@cisco.com> <20080506130108.O46817@sapphire.juniper.net> <4821FB01.90209@cisco.com>
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Cc: Ross Callon <rcallon@juniper.net>, rtg-bfd@ietf.org, dward@cisco.com
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Hi Carlos, <snipped> > > > >> If so, could the Security Considerations mention > >> that the GTSM is not in effect in that direction, > >> and with a routed > >> multi-hop reply? Or should it be set to 255 and GTSM-checked on receipt? > >> And in the egress -> ingress direction, should the TTL be set to 255 > >> (and checked for GTSM if the dest port if 3784, but not if the dest port > >> is 4784)? > >> > > > > The revised text will make it clear that for a routed reply > > [BFD-MHOP] applies and otherwise [BFD-IP] applies. I don't think > > there is any need to state the above here. > > Thanks. Would this apply only to encapsulation (since the text is within > the Encapsulation section), or also to the GTSM procedures from > [BFD-IP]? Could that be clarified as well, since it might not be > directly apparent? > I will clarify this. <snipped> > >> > >> On receipt of the LSP-Ping echo request message, the egress LSR MUST > >> send a BFD control packet to the ingress LSR. This BFD control > >> packet MUST set the Your Discriminator field to the discriminator > >> received from the ingress LSR in the LSP-Ping echo request message. > >> > >> I think this should additionally require successful FEC Validation > >> ("Validate FEC Stack" flag in the MPLS echo request) before sending a > >> BFD control packet back, or at least a successful (return-code 3) label > >> operation check on receipt of the MPLS Echo request. > >> > > > > This is normal LSP-Ping procedure. > > The normal LSP-Ping procedure generates an LSP-Ping reply with a result > code that could differ from "AOK", and could for example be "Replying > router has no mapping for the FEC at stack-depth <RSC>" or "No label > entry at stack-depth <RSC>"; in these cases, in the new procedures, I > think that the egress LSR should not send a BFD control packet (as there > is a FEC<->Label mismatch detected, and the feature of using LSP-Ping > with BFD so that "the presence of the FEC in the echo request message > makes is possible to verify the control plane against the data plane at > the egress LSR" would become a NOOP). Shouldn't the BFD session be > bootstrapped only after a successful control-plane checking (and ideally > including FEC Validation)? > I see there is value in clarifying this. Will do. <snipped> > > > > How about inserting the following text to clarify this: > > I think this clarifies, with two small comments inline, thanks: > > > > > "To enable fault detection procedures specified in this document, for a > > particular MPLS LSP, this document requires the ingress and > > egress LSRs to be configured. This includes configuration for supporting > > BFD and LSP-Ping as specified in this document. It also includes > > configuration that enables to the ingress LSR to determine the > ^ > or signaling > The whole point is that this document does not specify any signaling to discover the ingress/egress capabilities. It relies on configuration. > > method used by the egress LSR to identify OAM packets e.g. whether the TTL > > of the innermost MPLS label needs to be set to 1 to enable the egress LSR > > to identify the OAM packet. This applies to fault detection for MPLS PWs > > as well. > > "For fault detection for MPLS PWs, this document also assume that a PW > control channel (e.g., a PW-ACH) and support for LSP-Ping are provided > prior to initializing the procedures specified in this document, as > specified in [RFC5085]. " > > or something along those lines. > I don't think that makes sense as this document relies on configuration. Further there is no point in signaling LSP-Ping capability if BFD capability cannot be signaled. I fail to see why it is not enough to spell out that this document requires configuration. It doesn't preclude capability signaling to be added by another document. > > Extending [RFC5085] procedures to signal BFD capability > > between PW endpoints is outside the scope of this document." > > > > Should this pointer to [RFC5085] be normative, and the one to > pwe3-vccv-bfd in "The use of BFD for PWs is further described in [VCCV] > and [OAM-MAP]." be informative? > Both should be informative pointers. rahul
- WGLC comments on bfd-mpls-05 Carlos Pignataro
- [BFD] bfd-mpls-05 Damodharan SP - TLS , Chennai
- Re: [BFD] bfd-mpls-05 Carlos Pignataro
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal
- Re: WGLC comments on bfd-mpls-05 Carlos Pignataro
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal
- Re: WGLC comments on bfd-mpls-05 Carlos Pignataro
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal
- Re: WGLC comments on bfd-mpls-05 Carlos Pignataro
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal
- Re: WGLC comments on bfd-mpls-05 Nadeau Thomas
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal
- Re: WGLC comments on bfd-mpls-05 Carlos Pignataro
- Re: WGLC comments on bfd-mpls-05 Rahul Aggarwal