Re: [mpls] [Technical Errata Reported] RFC3031 (6450)

[Adrian Farrel <[e-mail]>]

Hi,

I looked through this and reread 3031 (if may have been a few years).

While I can agree that there is "potential for confusion" in the use of "L2"
and "L3", I agree with Stewart that not many people have reported being
confused in the last 20 years (happy birthday, RFC 3031!).

Perhaps an easier fix (if a fix is needed at all - I don't believe it is) is
to remove the abbreviations "L2" and "L3". 

For "L2"
2.3 Remove L2
3.23 s/L2/layer 2/ twice

For "L3"
2.2 s/L3/layer 3/ three times
2.3 Remove L3
3.17 s/L3/layer 3/ 
4.15 s/L3/layer 3/
5.1.1.2 s/L3/layer 3/ twice
5.1.2.2 s/L3/layer 3/
5.1.3 s/L3/layer 3/
5.1.4 s/L3/layer 3/
5.1.4.2 s/L3/layer 3/
5.1.5 s/L3/layer 3/ four times
5.1.5.1 s/L3/layer 3/
5.2.2 s/L3/layer 3/

Maybe pop that list of changes in the report, mark it as Editorial, and move
on?

Cheers,
Adrian

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Subject: [mpls] [Technical Errata Reported] RFC3031 (6450)

The following errata report has been submitted for RFC3031,
"Multiprotocol Label Switching Architecture".

--------------------------------------
You may review the report below and at:
https://www.rfc-editor.org/errata/eid6450

--------------------------------------
Type: Technical
Reported by: Duane L. Anderson <[e-mail]>

Section: GLOBAL

Original Text
-------------
2.2. Terminology defines the terms

        Layer 2         layer 2 the protocol layer under layer 3 
                        (which therefore offers the services used by layer
3)
        Layer 3         the protocol layer at which IP and its associated 
                        routing protocols operate

2.3. Acronyms and Abbreviations defines 

        L2              Layer 2
        L3              Layer 3

However, in 3.14. Scope and Uniqueness of Labels, 4.3. Label Stacks and
Implicit Peering, 4.5. LSP Trees as Multipoint-to-Point Entities, and 4.6.
LSP Tunneling between BGP Border Routers, L1, L2 and L3 are used as
differentiating names for certain labels attached to packets. 

Of course, in 3.23. Time-to-Live (TTL), L2 is used to refer to layer 2 frame
header and to a layer 2 switch, which is correct. 

However, in 4.3. Label Stacks and Implicit Peering, the term level 1 is used
to refer to the LIFO (stack) ordinal number of a label then named L1 and
given a protocol layer 2 protocol of layer 2 (L2). Furthermore, labels named
L2 and then L1 are pushed onto the stack of labels prefixed to the packet.
To top it all off the packet's stack attribute as protocol level 2 (L2). 

Of course, in 3.17. LSP Next Hop, 4.1.5. The Implicit NULL Label, 5.1.1.2.
PushConditional, 5.1.1.4. PulledConditional, 5.1.2.2. RequestWhenNeeded,
5.1.3. Upstream LSR: NotAvailable Procedure, 5.1.4. Upstream LSR: Release
Procedure, 5.1.4.2. NoReleaseOnChange, 5.1.5. Upstream LSR: labelUse
Procedure, 5.2.2. Schemes for LSRs that do not Support Label Merging, refer
to L3 meaning level 3, which is correct. 

Furthermore, in 3.1. Labels, 3.2. Upstream and Downstream LSRs, 3.4. Label
Assignment and Distribution, 3.5. Attributes of a Label Binding, 3.14. Scope
and Uniqueness of Labels, 4.1.2.2. Distributing Labels, 5.1.5. Upstream LSR:
labelUse Procedure, 5.1.5.2. UseIfLoopNotDetected, 5.1.6. Downstream LSR:
Withdraw Procedure

 * L is used as a name for a certain label attached to packet, and 

 * L is used as a arbitrary value assigned to a label attached to a packet


Corrected Text
--------------
I have not provided any corrected text as I've literally "highlighted" 44
places in a pdf format file of RFC 3031 that are ambiguous. 

As there is no facility to attach a file to this Report Errata for RFC3031
form, i will send the file commented pdf file upon request. 

Notes
-----
My rational for highlighting (no pun intended) these problems is that the
overloading of the L2, L3 abbreviations layer 2 and layer 3, with the names
L1, L2, L3 and L for labels, plus the use of L1 and L2 as indexed names for
the ordinal position of a label prefixed to a payload, then to use L2 and L3
as to actually mean layer 2 and layer is uh ... sloppy. 

Honestly, I can't understand how RFC 3031 has been posted for twenty years
and that it is on the Standards Track and no one has found these problems. 

Its similar to when someone publishes a mathematical treatise and use the
same set of variable names {x, y, z, t} over and over again in different
contexts spread throughout the paper. Its intractable and practically
gibberish. 

I apologize if my criticism is harsh regarding this problem but I spent a
considerable amount of my time reading this document trying to make sense of
it before I realized that the fault is not mine but it is of the document.

Instructions:
-------------
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--------------------------------------
RFC3031 (draft-ietf-mpls-arch-06)
--------------------------------------
Title               : Multiprotocol Label Switching Architecture
Publication Date    : January 2001
Author(s)           : E. Rosen, A. Viswanathan, R. Callon
Category            : PROPOSED STANDARD
Source              : Multiprotocol Label Switching
Area                : Routing
Stream              : IETF
Verifying Party     : IESG

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