Re: [Idr] AD Review of draft-ietf-idr-eag-distribution-15
Jeff Tantsura <jefftant.ietf@gmail.com> Sun, 18 April 2021 23:47 UTC
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Date: Sun, 18 Apr 2021 16:47:11 -0700
From: Jeff Tantsura <jefftant.ietf@gmail.com>
To: draft-ietf-idr-eag-distribution@ietf.org, Alvaro Retana <aretana.ietf@gmail.com>
Cc: Susan Hares <shares@ndzh.com>, idr-chairs@ietf.org, IDR List <idr@ietf.org>
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Subject: Re: [Idr] AD Review of draft-ietf-idr-eag-distribution-15
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HI Alvaro, Many thanks for your thoughtful review, please see inline (updated version has been published) Cheers, Jeff On Mar 30, 2021, 1:25 PM -0700, Alvaro Retana <aretana.ietf@gmail.com>, wrote: > Dear authors: > > Here is my review of this document. I have some major comments (see > inline below) that should be easy to address and that I would like to > see reflected in the text before starting the IETF Last Call. > > Thank you for your work! > > Alvaro. > > > [Line numbers from idnits.] > > > 11 Distribution of Traffic Engineering Extended Admin Groups using BGP-LS > > [minor] s/Admin/Administrative [jeff] ack > > > 12 draft-ietf-idr-eag-distribution-15 > > 14 Abstract > > 16 Administrative groups are link attributes (commonly referred to as > 17 "colors" or "link colors") advertised by link state protocols (e.g. > 18 ISIS or OSPF) and used for traffic engineering. These administrative > 19 groups were initially defined as 32 bit masks. As network usage > 20 grew, these 32 bit masks were found to constrain traffic engineering. > 21 Therefore, link state protocols (ISIS, OSPF) were expanded to > 22 advertise a variable length administrative group.This document > 23 defines an extension to BGP-LS for advertisement of extended > 24 administrative groups (EAGs) to allow to support a number of > 25 administrative groups greater than 32, as defined in [RFC7308]. > > [minor] A couple of changes to simplify. The details can be found in > the Introduction. [jeff] ack > > Suggestion> > Administrative groups are link attributes advertised used for traffic > engineering. This document defines an extension to BGP-LS for > advertisement of extended administrative groups (EAGs). > > > ... > 70 1. Introduction > > 72 Administrative groups (commonly referred to as "colors" or "link > 73 colors") are link attributes that are advertised by link state > 74 protocols like IS-IS [RFC5305], OSPFv2 [RFC3630] and OSPFv3 [RFC5329] > 75 for traffic engineering use-cases. The BGP-LS advertisement of the > 76 originally defined (non-extended) administrative groups is encoded > 77 using the Administrative Group (color) TLV 1088 as defined in > 78 [RFC7752]. [jeff] ack > > [minor] "IS-IS [RFC5305], OSPFv2 [RFC3630] and OSPFv3 [RFC5329]" > These references should point at the protocols themselves, not the TE > extensions. Also, these references can be Informative. [jeff] ack, changed [jeff] Alvaro - this is the text from 7308, that specifically calls out TE documents - "This document defines the Extended Administrative Group (EAG) sub-TLVfor both OSPF [RFC3630] and IS-IS [RFC5305].” ? > > > 80 These administrative groups are defined as a fixed-length 32-bit > 81 bitmask. As networks grew and more use-cases were introduced, the > 82 32-bit length was found to be constraining and hence extended > 83 administrative groups (EAG) were introduced in the IS-IS and OSPFv2 > 84 link state routing protocols [RFC7308]. > > [minor] rfc7308 also includes OSPFv3. > > s/were introduced in the IS-IS and OSPFv2 link state routing protocols > [RFC7308]./were introduced in [RFC7308]. [jeff] ack > > > ... > 97 2. Advertising Extended Administrative Groups in BGP-LS > > 99 This document defines an extension that enable BGP-LS speakers to > 100 signal the EAG of links in a network to a BGP-LS consumer of network > 101 topology such as a centralized controller. The centralized > 102 controller can leverage this information in traffic engineering > 103 computations and other use-cases. When a BGP-LS speaker is > 104 originating the topology learnt via link-state routing protocols like > 105 OSPF or IS-IS, the EAG information of the links is sourced from the > 106 underlying extensions as defined in [RFC7308]. The BGP-LS speaker > 107 may also advertise the EAG information for the local links of a node > 108 when not running any link-state IGP protocol e.g. when running BGP as > 109 the only routing protocol. > > [minor] There is no defined mechanism to originate EAG information > when not running a link-state protocol. Let's take the last sentence > out. > [jeff] ack > > 111 The EAG of a link is encoded in a new Link Attribute TLV [RFC7752] > 112 using the following format: > > 114 0 1 2 3 > 115 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 > 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > 117 | Type | Length | > 118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > 119 | Extended Administrative Groups (variable) // > 120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > [minor] Maybe use the same representation as rfc7308 for the format. [jeff] this is the standard way to represent encodings in BGP-LS documents, I think readers are more comfortable with this representation, please let me know what you think. > > > ... > 128 o Length: variable length which represents the total length of the > 129 value field. The length value MUST be multiple of 4. If the > 130 length is not a multiple of 4, the TLV MUST be considered > 131 malformed. > > [major] "total length of the value field" What are the units? [jeff ack] > > > 133 o Value: one or more sets of 32-bit bitmasks that indicate the > 134 administrative groups (colors) that are enabled on the link when > 135 those specific bits are set. > > [major] rfc7308 talks about an "Extended Admin Group" (singular!), and > not a set of groups. This TLV is then not in line with rfc7308. > > The whole document should be checked for (editorial) compliance with > the concept of a single EAG. > [jeff] ack, i believe now it reads correct > > 137 The EAG TLV is an optional TLV. The originally defined AG TLV 1108 > 138 and the EAG TLV 1173 defined in this document MAY be advertised > 139 together. The semantics of the EAG and the backward compatibility > 140 aspects of EAG with respect to the AG are handled as described in the > 141 Backward Compatibility section of [RFC7308], namely - If a node > 142 advertises both AG and EAG, then the first 32 bits of the EAG MUST be > 143 identical to the advertised AG. > > [minor] We don't really need this paragraph because any compatibility > or checking is outside of what BGP-LS does (just transport). Please > remove it. > [jeff] ack > > ... > 158 4. Security Considerations > > 160 The extensions in this document advertise same administrative group > 161 information specified via [RFC7752] but as a larger/extended value > 162 and hence does not introduce security issues beyond those discussed > 163 in [RFC7752] and [I-D.ietf-idr-rfc7752bis]. > > [major] No need to mention rfc7752bis -- at all! > > [major] Please take a look at the Security Considerations in rfc8814 > and copy them here -- with appropriate modifications to talk about EAG > instead of MSD, of course. > [jeff] ack > > [End of Review]
- [Idr] AD Review of draft-ietf-idr-eag-distributio… Alvaro Retana
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Jeff Tantsura
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Alvaro Retana
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Ketan Talaulikar (ketant)
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Les Ginsberg (ginsberg)
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Jeff Tantsura
- Re: [Idr] AD Review of draft-ietf-idr-eag-distrib… Alvaro Retana