Re: [Detnet] adoption of draft-dt-detnet-dp-alt-03?

["Grossman, Ethan A." <[e-mail]>]

Yes I support the draft. This is a really well-crafted document, excellent work Jouni et al.

As I was reading it I made a number of notes about mostly grammatical things that could/should be fixed, along with proposed text for each, and the occasional question about the intended meaning of a phrase. These are listed below.

If you want, I could sign up to make these changes to the draft, but they would need to be proofread to make sure I didn’t misunderstand the ideas.

My intent is not to nit pick, but I feel that a draft that has grammatical errors comes off as one that hasn’t yet had enough eyes on it, so I am trying to support credibility of the draft in my own simple way (i.e. I have nothing useful technical to say, I’m just learning from the draft).

Sincerely,
Ethan.

--------------- Ethan’s comments on draft-dt-detnet-dp-alt-03 -----------------

p.4 - DetNet Transport Layer – “All DetNet nodes are end points and the transport layer.”
? What is this trying to say?

4.1. #1 Encapsulation and overhead: “In addition to the encapsulation mechanism this criteria is also concerned of the processing and specifically the encapsulate header overhead. “
? Fix grammar, e.g. “concerned with”, “encapsulation header”.

4.2. #2 Flow identification : “The flow identification can, for example, be explicit field in the data plane encapsulation header”
? Fix typo e.g. “be an explicit field”.

4.3. #3 Packet sequencing and duplicate elimination: “In addition to possible reordering packets other important uses for sequencing are detecting duplicates and lost packets.”
? Fix typo e.g. “reordering of packets,”.

4.6. #6 Operations, Administration and Maintenance: ”The solution alternative should demonstrate an availability of appropriate standardized OAM tools”
? Fix grammar e.g. “demonstrate availability”

4.7. #8 Class and quality of service capabilities: “Hereto, certain aspects of CoS and QoS may be provided by the underlying sub-net technology”
? Unusual language, suggest “For DetNet, certain aspects“

5.1.1.3. Summary: “IPv6 may be a choice as the DetNet Transport layer in networks where other technologies such as MPLS are not deployed.”
? Does this mean there will be multiple dataplane solutions? I thought the point was to choose one?

5.1.2.1. Solution description: “but these have historically not been supported on in hardware-based forwarding”
? Fix typo, e.g. “but historically these have not been supported in hardware-based forwarding”

5.1.3. Multiprotocol Label Switching (MPLS): “The remainder of this section will focus [RFC6373]. The remainder of this section will focus on the MPLS transport data plane, additional information on the MPLS service data plane can be found below”
? Consolidate these two sentences, or maybe clarify or eliminate first sentence?

5.1.3.2. Analysis and Discussion #1 Encapsulation and overhead (M): “The second perspective relates to encapsulation, if any, is needed to transport packets across network.”
? Fix grammar, e.g. “perspective relates to the encapsulation, if any, which is needed to transport packets across the network”

5.1.3.2. Analysis and Discussion #5 Flow duplication and merging: “there are mechanisms defined to provide 1+1 protection, which could help realizing the flow merging function
? Fix grammar e.g. “realize” or “in realizing”

5.1.4. Bit Indexed Explicit Replication (BIER)
? This section should be called “Bit Indexed Explicit Replication (BIER) over MPLS”, right? Otherwise it sounds like a competitor of ipv6, MPLS, etc.

Ibid “the technology faces a lot of traction”
? “Facing” has negative connotation, you want something positive like “is getting a lot”

Ibid. “Section 5.1.4 discusses the applicability of BIER for replication in the DetNet.”
? Fix wording, suggest “In the context of DetNet, BIER may be applicable for implementing packet replication, as described in section 5.1.4”.

Ibid. “Bit-Indexed Explicit Replication (BIER) layer may be considered to be included into Deterministic Networking data plane solution.”
? No new information in this sentence, suggest deleting it.

Ibid. “Encapsulation of a BIER packet in MPLS network presented in Figure 8”
? Fix grammar, suggest “The encapsulation of a BIER packet in an MPLS network is shown in Figure 8”

5.1.4.1. Solution description: “The DetNet may be presented in BIER as distinctive payload type with its own Proto(col) ID. Then it is likely that DetNet will have the header that would identify”
? Reword for clarity and to fix grammar, suggest “A distinctive BIER payload type (with its own Protocol ID) would be created for DetNet, providing a header that would identify:”

Ibid. “DetNet node, collocated with BFIR, may use multiple BIER sub-domains to create replicated flows. Downstream DetNet nodes, collocated with BFER, would terminate redundant flows based on Sequence Number and/or Timestamp information. Such DetNet may be BFER in one BIER sub- domain and BFIR in another. Thus DetNet flow would traverse several BIER sub-domains.”
? ? Reword for clarity and to fix grammar, suggest “A DetNet node, collocated with a BFIR (Bit-Forwarding Ingress Router) may use multiple BIER sub-domains to create replicated flows. Downstream DetNet nodes, collocated with BFER (Bit-Forwarding Ingress Router) would terminate redundant flows based on Sequence Number and/or Timestamp information. Thus a DetNet node may be collocated with a BFER in one BIER sub- domain and with a BFIR in another, and a DetNet flow could traverse several BIER sub-domains.” [note: is “node” the right term here?]

Ibid. “Consider DetNet flow”
? Fix grammar, suggest “Consider a DetNet flow”

Ibid. “those that deemed too-late”
? Fix grammar, suggest “those that are deemed “too-late””.

5.1.4.2. Analysis and Discussion #1 Encapsulation and overhead: “(will refer as "BIER over MPLS" further for short), Figure 8, is being defined [I-D. ietf- bier-mpls-encapsulation]”
? Fix grammar, suggest “("BIER over MPLS")”

Ibid. “[I-D. ietf- bier-mpls-encapsulation]”
? Fix ineffective link

Ibid. “#5 Flow duplication and merging: “is core function”
? Fix grammar, e.g. “is a core function”.

Ibid. #6: “Some OAM protocols, e.g. can be applied and used in BIER over MPLS as demonstrated [I-D.ooamdt-rtgwg-oam-gap-analysis], while new protocols being worked on”
? Fix grammar, e.g. “Existing OAM protocols can be applied and used in BIER over MPLS as demonstrated in [I-D.ooamdt-rtgwg-oam-gap-analysis], while new protocols are being worked on”

Ibid. #8: “constrains”
? Fix spelling, “constraints”.

Ibid. “calculating explicit path”
? Fix grammar, “calculating explicit paths”.

5.1.5.1. Solution description: “BIER-TE enables to activate”
? Fix grammar, suggest “enables activation of”

Ibid. “Adversely”
? Wrong word, you mean “Conversely”.

Ibid. “In more details”
? Fix grammar, “in more detail”

Ibid. “BIER-TE also enables to detect the failing adjacencies”
? Fix grammar, e.g. “BIER-TE also enables detection of failing adjacencies”

Ibid. “enables to avoid”
? Fix grammar, “enables avoiding”

5.1.5.2. Analysis and Discussion #5 Flow duplication and merging “M/W) The bitmap expresses in a very concise fashion which replication and merging (and elimination) should take place for a given packet. It also enables to control that process on a per packet basis, depending on the loss that it enables to measure.”
? Fix missing paren “(M/W)”.
? “enables to control” should be “enables controlling”.
? I don’t understand what this means “depending on the loss that it enables to measure” – please clarify.

Ibid. #6: “enables to determine”
? Fix grammar, e.g. “enables determination of”

Ibid. #9 Packet traceability (W): “enables to determine which is”
? Fix grammar, e.g. “enables determination of”

Ibid. #10: “as is not fully defined.”
?Fix grammar, “and is not fully defined”.

5.1.5.3. Summary: “In the one hand it is optional, and only useful if replication and elimination is taking place. In the other hand,”
? Fix grammar, the expression is “On the one hand… on the other hand”.

5.2.2. MPLS-based Services for DetNet: “MPLS based technologies supports both the DetNet Service and DetNet Transport layers. This, as well as a general overview of MPLS, is covered above in Section 5.1.3.”
? Grammar: “supports” should be “support”.

Ibid. “These sections focus on the DetNet Service Layer”
? Do you mean the previous sections or the following sections?

Ibid. “it provides client service adaption, via Pseudowires”
? Not sure what you mean here. Is it “These sections focus on the DetNet Service Layer which provides client service adaption, via Pseudowires”?

Ibid. “MPLS can thus also bounded by”
? Fix typo, “can thus also be bounded by”

Ibid. “While MPLS service can provided on and true end-system to end- system basis,”
? Fix typo, suggest “on a true”

5.2.3.2. Analysis and Discussion #1 Encapsulation and overhead (M) “PWs offer encapsulation services practically for any types of payloads over any PSN”
? Fix grammar, e.g. “PWs offer encapsulation services for practically any type of payload over any PSN”

Ibid. #2 Flow identification (M) “the MPLS PSN also uses one or more labels to transport packets over a specific label switched paths”.
? Fix grammar, I think you want “over specific label switched paths”

Ibid. “#5 Flow duplication and merging (W) “transport leyer connection, though”
? Fix typo “layer”.
? Eliminate extra word “, though”.

Ibid #6 “likewise IP PSN have the full toolbox”
? Fix typo “has the full toolbox”.

Ibid. #8: “Due to the limited number of bits in the TC field, their use for QoS and ECN functions restricted and intended to be flexible.”
? Do you mean  “their use for QoS and ECN functions is restricted and is not intended to be flexible.”? Please fix wording.

Ibid. #10 “already get close”
? Fix typo “already gets close”

I am starting to understand that some networks support MPLS and some don’t, so if we depend on MPLS we have to have a backup plan for IP based networks. Is that correct? If so maybe that should be explained somewhere early on, to make it clear that more than one solution must be considered.

5.2.5.2.1. Solution Description: “transposting RTP header”
? should be “transporting RTP headers”, right?

Ibid. “monitors of the data delivery”
? Fix typo “monitors the data delivery”

5.2.5.2.2 #2 Flow identification: “no two synchronization sources within the same RTP session has the same SSRC identifier”
? Fix grammar “have the same SSRC identifier”.

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From: detnet [mailto:[e-mail]] On Behalf Of Pat Thaler
Sent: Tuesday, August 23, 2016 11:08 AM
To: [e-mail]
Subject: Re: [Detnet] adoption of draft-dt-detnet-dp-alt-03?

I mean Sept 5 - two week poll plus a bit since it was sent towards the end of a Friday.

On Fri, Aug 19, 2016 at 11:53 AM, Pat Thaler <[e-mail]<mailto:[e-mail]>> wrote:
All,

This is start of a two-week poll on making
draft-dt-detnet-dp-alt-03 a working group document. Please
send email to the list indicating "yes/support" or "no/do not
support". If indicating no, please state your reservations with the
document.  If yes, please also feel free to provide comments you'd
like to see addressed once the document is a WG document.

The poll ends Sept 5, 2016

Thanks,
Pat Thaler