Hi Fabio, That additional text is helpful, thanks. Adrian > -----Original Message----- > From: Fabio Maino [mailto:fmaino@xxxxxxxxx] > Sent: 15 August 2018 19:15 > To: Adrian Farrel; rtg-dir@xxxxxxxx > Cc: lisp@xxxxxxxx; ietf@xxxxxxxx; draft-ietf-lisp-gpe.all@xxxxxxxx > Subject: Re: Rtgdir last call review of draft-ietf-lisp-gpe-04 > > Hi Adrian, > thanks for such a detailed review. > > I went through your comments and I can incorporate all of them into a > new version of the draft. > > Wrt the reduction in size of the Map-Versioning and Nonce fields, I > could add in Section 3, right after the definition of the encoding of > those fields, the following: > > > The encoding of the Nonce field in LISP-GPE, compared with the one > > used in RFC6830bis for the LISP data plane encapsulation, reduces the > > length of the nonce from 24 to 16 bits. As per RFC6830bis, ITRs are > > required to generate different nonces when sending to different RLOCs, > > but the same nonce can be used for a period of time when encapsulating > > to the same ETR. The use of 16 bits nonces still allows an ITR to > > determine to and from reachability for up to 64k RLOCs at the same time. > > > > Similarly, the encoding of the Source and Dest Map-Version fields, > > compared with RFC6830bis, is reduced from 12 to 8 bits. This still > > allows to associate 256 different versions to each EID-to-RLOC mapping > > to inform commmunicating ITRs and ETRs about modifications of the > > mapping. > > > > > Either Deborah, Joel, or Luigi: if you could please confirm that it is > ok to publish a new version of the draft at this point, I'll update it > right away. > > Thanks, > Fabio > > > > > On 8/9/18 9:05 AM, Adrian Farrel wrote: > > Reviewer: Adrian Farrel > > Review result: Has Issues > > > > Hello, > > > > I have been selected as the Routing Directorate reviewer for this draft. The > > Routing Directorate seeks to review all routing or routing-related drafts as > > they pass through IETF last call and IESG review, and sometimes on special > > request. The purpose of the review is to provide assistance to the Routing ADs. > > For more information about the Routing Directorate, please see > > ?http://trac.tools.ietf.org/area/rtg/trac/wiki/RtgDir > > > > Although these comments are primarily for the use of the Routing ADs, it would > > be helpful if you could consider them as normal review comments. I believe > that > > this review comes between WG publication and the start of IETF last call - you > > may wish to discuss with your AD whether to treat these comments separately > or > > as part of IETF last call. > > > > Document: draft-ietf-lisp-gpe-04.txt > > Reviewer: Adrian Farrel > > Review Date: 9-August-2018 > > IETF LC End Date: No known > > Intended Status: Standards Track > > > > Summary > > I have significant concerns about this document and recommend that the > Routing > > ADs discuss these issues further with the authors. The issues are not > > substantially technical in nature, but do indicate the need for significant > > reworking of the text. I have tried to make suggestions for new text. > > > > Comments: > > > > This document specifies an alternate LISP header format that can be used to > > allow LISP to carry payloads other than IP. A new capabilities flag is defined > > so that routers know whether this new format is supported, and a new flag in > > the header itself indicates when the new format is in use. > > > > The document is clear and readable, but has some issues of presentation that > > could close a few potential misunderstandings and thus improve implmentation > > prospects. > > > > No attempt is made in the document to explain how/why the reduction in size > of > > some standard LISP header fields is acceptable. For example, if > implementations > > of this spec can safely operate with a 16 bit Nonce or 8 bit Map-Versions, why > > does 6830/6830bis feel the need for 24 and 12 bit fields rspectively? > > > > ===Major Issues=== > > > > Section 3 has a mix of minor and leess minor issues... > > > > OLD > > This document defines the following changes to the LISP header in > > order to support multi-protocol encapsulation: > > > > P Bit: Flag bit 5 is defined as the Next Protocol bit. The P bit > > MUST be set to 1 to indicate the presence of the 8 bit next > > protocol field. > > > > P = 0 indicates that the payload MUST conform to LISP as defined > > in [I-D.ietf-lisp-rfc6830bis]. Flag bit 5 was chosen as the P bit > > because this flag bit is currently unallocated. > > > > Next Protocol: The lower 8 bits of the first 32-bit word are used to > > carry a Next Protocol. This Next Protocol field contains the > > protocol of the encapsulated payload packet. > > > > LISP uses the lower 24 bits of the first word for either a nonce, > > an echo-nonce, or to support map-versioning > > [I-D.ietf-lisp-6834bis]. These are all optional capabilities that > > are indicated in the LISP header by setting the N, E, and the V > > bit respectively. > > > > When the P-bit and the N-bit are set to 1, the Nonce field is the > > middle 16 bits. > > > > When the P-bit and the V-bit are set to 1, the Version field is > > the middle 16 bits. > > > > When the P-bit is set to 1 and the N-bit and the V-bit are both 0, > > the middle 16-bits are set to 0. > > > > This document defines the following Next Protocol values: > > > > 0x1 : IPv4 > > > > 0x2 : IPv6 > > > > 0x3 : Ethernet > > > > 0x4 : Network Service Header [RFC8300] > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > |N|L|E|V|I|P|K|K| Nonce/Map-Version | Next Protocol | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | Instance ID/Locator-Status-Bits | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > LISP-GPE Header > > > > NOTES > > - It would be helpful to put the figure higher up > > - The use of "MUST" for the P-bit is attenuated wrongly > > - Need to be consistent on "P Bit" or "P-bit" or "P bit" > > - There looks to be a problem in the case of map version. The base > > spec has 12 bits each for source and dest map-version, so this doc > > needs to describe how the reeduced 16 bits is split (presumably not > > 12 and 4). > > - You need a pointer to the IANA registry for next protocol > > NEW > > This document defines two changes to the LISP header in order to > > support multi-protocol encapsulation: the introduction of the P-bit > > and the definition of a Next Protocol field. This is shown in > > Figure 1 and described below. > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > |N|L|E|V|I|P|K|K| Nonce/Map-Version | Next Protocol | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | Instance ID/Locator-Status-Bits | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > Figure 1 : The LISP-GPE Header > > > > P-Bit: Flag bit 5 is defined as the Next Protocol bit. > > > > If the P-bit is clear (0) the LISP header conforms to the > > definition in [I-D.ietf-lisp-rfc6830bis]. > > > > The P-bit is set to 1 to indicate the presence of the 8 bit Next > > Protocol field. > > > > Next Protocol: The lower 8 bits of the first 32-bit word are used to > > carry a Next Protocol. This Next Protocol field contains the > > protocol of the encapsulated payload packet. > > > > In [I-D.ietf-lisp-6834bis], LISP uses the lower 24 bits of the > > first word for a nonce, an echo-nonce, or to support map- > > versioning. These are all optional capabilities that are > > indicated in the LISP header by setting the N, E, and V bits > > respectively. > > > > When the P-bit and the N-bit are set to 1, the Nonce field is the > > middle 16 bits (i.e., encoded in 16 bits, not 24 bits). Note that > > the E-bit only has meaning when the N-bit is set. > > > > When the P-bit and the V-bit are set to 1, the Version fields use > > the middle 16 bits: the Source Map-Version uses the high-order 8 > > bits, and the Dest Map-Version uses the low-order 8 bits. > > > > When the P-bit is set to 1 and the N-bit and the V-bit are both 0, > > the middle 16-bits MUST be set to 0 on transmission and ignored on > > receipt. > > > > This document defines the following Next Protocol values: > > > > 0x1 : IPv4 > > > > 0x2 : IPv6 > > > > 0x3 : Ethernet > > > > 0x4 : Network Service Header [RFC8300] > > > > The values are tracked in an IANA registry as described in Section > > 5. > > > > --- > > > > Section 4 must describe the error case when a LISP-GPE capable router > > sets the P-bit on a packet to a non LISP-GPE capable router. So... > > > > OLD > > When encapsulating IP packets to a non LISP-GPE capable router the P > > bit MUST be set to 0. > > NEW > > When encapsulating IP packets to a non LISP-GPE capable router the P- > > bit MUST be set to 0. That is, the encapsulation format defined in > > this document MUST NOT be sent to a router that has not indicated > > that it supports this specification because such a router would > > ignore the P-bit (as described in [I-D.ietf-lisp-rfc6830bis]) and so > > would misinterpret the other LISP header fields possibly causing > > significant errors. > > END > > > > --- > > > > 4.1 > > > > Not your fault that RFC 8060 doesn't have a registry for bits in the > > LCAF, but now you really need one or else future orthogonal specs risk > > colliding with the g-bit. A bit odd to add this in this document, but > > not worth a bis on 8060. > > > > ===Minor Issues === > > > > Section 2 > > > > OLD > > The LISP header [I-D.ietf-lisp-rfc6830bis] contains a series of flags > > (some defined, some reserved), a Nonce/Map-version field and an > > instance ID/Locator-status-bit field. The flags provide flexibility > > to define how the various fields are encoded. Notably, Flag bit 5 is > > the last reserved bit in the LISP header. > > > > 0 1 2 3 > > 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > |N|L|E|V|I|R|K|K| Nonce/Map-Version | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > | Instance ID/Locator-Status-Bits | > > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > LISP Header > > NOTES > > We need to be careful not to risk any confusion. At least, "some > > reserved" is an over-statement. But also we should not show a repeat > > of the Lisp header as that causes a duplicate definition. > > NEW > > The LISP header is defined in [I-D.ietf-lisp-rfc6830bis] and contains > > a series of flags of which one (bit 5) is shown in that document as > > "reserved for future use". The setting of the flag fields defined > > how the subsequent header fields are interpretted. > > END > > > > --- > > > > 4.1 > > I don't think you should reproduce the Multiple Data-Planes LCAF Type > > figue from 8060 here as it creates a duplicate definition. The text > > explanation of which bit is the g-bit shold be enough. > > > > ===Nits=== > > > > Abstract > > OLD > > This document describes extending the Locator/ID Separation Protocol > > (LISP) Data-Plane, via changes to the LISP header, to support multi- > > protocol encapsulation. > > NEW > > This document describes extentions to the Locator/ID Separation > > Protocol (LISP) Data-Plane, via changes to the LISP header, to > > support multi-protocol encapsulation. > > END > > > > --- > > > > 1. > > OLD > > LISP Data-Plane, as defined in in [I-D.ietf-lisp-rfc6830bis], defines > > an encapsulation format that carries IPv4 or IPv6 (henceforth > > referred to as IP) packets in a LISP header and outer UDP/IP > > transport. > > NEW > > The LISP Data-Plane is defined in [I-D.ietf-lisp-rfc6830bis]. It > > specifies an encapsulation format that carries IPv4 or IPv6 packets > > (henceforth jointly referred to as IP) in a LISP header and outer > > UDP/IP transport. > > > > --- > > > > 1.1 > > Please use the new boilerplate... > > The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", > > "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", > "MAY", and > > "OPTIONAL" in this document are to be interpreted as described in BCP > > 14 [RFC2119] [RFC8174] when, and only when, they appear in all > > capitals, as shown here. > > > > --- > > > > 1.2 > > Nothwithstanding the text in this section, abbreviations need to be > > expanded either on first use or in this section. > > I see: > > - LCAF > > - ETR > > - ITR > > - RLOC > > - xTR > > > > --- > > > > 2. > > s/As described in the introduction/As described in Section 1/ > > s/LISP is limited to carry IP payloads/LISP is limited to carrying IP payloads/ > > > > --- > > > > 4.1 > > s/field as g bit/field as the g-bit/ > > > > --- > > > > 8.1 > > Please add RFC 8174 > >
