Hi Ron,
keeping the normative statements aside.
We are defining a Generic Metric TLV.
1. The first and only defined usage at this point is for Flex-algo.
2. Generic Metric is not something that must be defined as application
independent, on the contrary, it's a value that is either assigned by
operator or computed somehow. Advertising application specific values
not only make sense, but would add value. TE metric is an example which
is very close to Generic Metric and is supported in ASLA.
3. Flex-algo is an application from the ASLA framework perspective and
so far is only using ASLA encoded link attributes. It would make sense
to continue to do so for Generic Metric.
4. If you feel you need the Generic Metric also as an application
independent value, I'm fine, although I do not see the immediate use case.
Given the above, would not you thing that advertising Generic Metric in
ASLA make sense?
thanks,
Peter
On 23/07/2021 06:13, Ron Bonica wrote:
Les,
Please, let us avoid discussion of whether my message is disingenuous. As Acee
will agree, discussion of my internal motivations and moral deficiencies is
beyond the scope of the LSR WG.
Now, let us address my point and your counter points. My point was that
draft-ietf-lsr-flex-algo-bw-con does not violate RFC 8919. Nothing more,
nothing less.
In your counterpoint #1, you point out tension between
draft-ietf-lsr-flex-algo-bw-con and draft-ietf-lsr-flex-algo. While this point
deserves discussion, it is orthogonal to my point. It is entirely possible that
both of the following statements are true:
- draft-ietf-lsr-flex-algo-bw-con does not violate RFC 8919
- there is tension between draft-ietf-lsr-flex-algo-bw-con and
draft-ietf-lsr-flex-algo
In your counterpoint #2, you talk about the "clear intent" of RFC 8919. Section
6.1 of RFC 8919 reduces that intent to a few very clear normative statements.
Draft-ietf-lsr-flex-algo-bw-con does not violate any of those normative statements.
Therefore, it does not violate RFC 8919.
You may say:
- Section 6.1 should have included more prohibitions
- The authors had additional prohibitions in mind when they wrote the draft,
but failed to add them to Section 6.1
That's all fine, but the community agreed only to the words on the page, not
the authors larger intent.
Ron
Juniper Business Use Only
-----Original Message-----
From: Les Ginsberg (ginsberg) <ginsberg=40cisco....@dmarc.ietf.org>
Sent: Thursday, July 22, 2021 2:49 PM
To: Ron Bonica <rbon...@juniper.net>; Acee Lindem (acee) <a...@cisco.com>; Shraddha Hegde
<shrad...@juniper.net>; gregory.mir...@ztetx.com; Peter Psenak (ppsenak)
<ppse...@cisco.com>; lsr@ietf.org
Cc: draft-ietf-lsr-flex-algo-bw-con.auth...@ietf.org
Subject: RE: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-bw-con-01.txt
[External Email. Be cautious of content]
Ron -
With respect, it is hard to read your email without feeling that it is
disingenuous.
But, let's cover the relevant points nonetheless.
Point #1:
https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/draft-ietf-lsr-flex-algo-17*section-12__;Iw!!NEt6yMaO-gk!XOCcoj-YdMkhznRiGAo1oeY1A6HMHuk5BDmsYqHAUf_hYgKb9tlp_Umpu3UxZFFM$
states:
" Link attribute advertisements that are to be used during Flex-
Algorithm calculation MUST use the Application-Specific Link
Attribute (ASLA) advertisements defined in [RFC8919] or [RFC8920]..."
As the new generic-metric is intended for use by flex-algo it needs to conform
to this normative statement.
Point #2:
RFC 8919 and 8920 were written to address ambiguities associated with the use
of multiple applications.
The Introduction sections of both documents discuss this in some detail.
The clear intent is to make use of ASLA going forward - not to restrict ASLA
only to the set of link attributes defined at the time of the writing of the
RFCs. Failure to do so would reintroduce the same set of issues that RFC
8919/8920 were written to address.
Your attempt to infer that because Generic-Metric was not defined at the time
that RFC 8919/8920 were written that the RFCs don’t apply to it makes no sense.
ASLA is in fact a revision to the link attribute architecture and is meant to
be used going forward.
The more appropriate question to ask is why we need to define a legacy style
sub-TLV for new link attributes? Ketan has made this point in his post on this
thread and I have sympathy with his position.
We do understand that legacy applications such as RSVP-TE may continue to be
deployed in networks for some time to come. It is not reasonable to expect that
legacy application implementations will be updated to use ASLA, which is why I
do not object to defining a legacy style encoding for Generic Metric if folks
believe that legacy applications may be enhanced to support new link attributes.
I strongly disagree with your interpretation that ASLA is limited only to the
code points defined in RFC 8919/8920.
Les
-----Original Message-----
From: Ron Bonica <rbonica=40juniper....@dmarc.ietf.org>
Sent: Thursday, July 22, 2021 10:28 AM
To: Acee Lindem (acee) <a...@cisco.com>; Les Ginsberg (ginsberg)
<ginsb...@cisco.com>; Shraddha Hegde <shrad...@juniper.net>;
gregory.mir...@ztetx.com; Peter Psenak (ppsenak) <ppse...@cisco.com>;
lsr@ietf.org
Cc: draft-ietf-lsr-flex-algo-bw-con.auth...@ietf.org
Subject: RE: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-bw-con-01.txt
Acee,
I don't think that draft-ietf-lsr-flex-algo-bw-con violates RFC 8919.
Section 6.1 of RFC 8919 says:
" New applications that future documents define to make use of the
advertisements defined in this document MUST NOT make use of legacy
advertisements. This simplifies deployment of new applications by
eliminating the need to support multiple ways to advertise attributes
for the new applications."
Section 3 of RFC 8919 defines legacy advertisements. The definition of
legacy advertisements does not include new attributes such as generic
metric. Therefore draft-ietf-lsr-flex-algo-bw-con does not violate RFC
8919
Relevant text from Section 3 of RFC 8919 is included below for convenience.
Ron
RFC 8919, Section 3
---------------------------
3. Legacy Advertisements
Existing advertisements used in support of RSVP-TE include sub-TLVs
for TLVs 22, 23, 25, 141, 222, and 223 and TLVs for Shared Risk Link
Group (SRLG) advertisement.
Sub-TLV values are defined in the "Sub-TLVs for TLVs 22, 23, 25, 141,
222, and 223" registry.
TLVs are defined in the "TLV Codepoints Registry".
3.1. Legacy Sub-TLVs
+======+====================================+
| Type | Description |
+======+====================================+
| 3 | Administrative group (color) |
+------+------------------------------------+
| 9 | Maximum link bandwidth |
+------+------------------------------------+
| 10 | Maximum reservable link bandwidth |
+------+------------------------------------+
| 11 | Unreserved bandwidth |
+------+------------------------------------+
| 14 | Extended Administrative Group |
+------+------------------------------------+
| 18 | TE Default Metric |
+------+------------------------------------+
| 33 | Unidirectional Link Delay |
+------+------------------------------------+
| 34 | Min/Max Unidirectional Link Delay |
+------+------------------------------------+
| 35 | Unidirectional Delay Variation |
+------+------------------------------------+
| 36 | Unidirectional Link Loss |
+------+------------------------------------+
| 37 | Unidirectional Residual Bandwidth |
+------+------------------------------------+
| 38 | Unidirectional Available Bandwidth |
+------+------------------------------------+
| 39 | Unidirectional Utilized Bandwidth |
+------+------------------------------------+
Table 1: Sub-TLVs for TLVs 22, 23, 25,
141, 222, and 223
Juniper Business Use Only
-----Original Message-----
From: Lsr <lsr-boun...@ietf.org> On Behalf Of Acee Lindem (acee)
Sent: Tuesday, July 20, 2021 1:21 PM
To: Les Ginsberg (ginsberg) <ginsberg=40cisco....@dmarc.ietf.org>;
Shraddha Hegde <shrad...@juniper.net>; gregory.mir...@ztetx.com;
ppsenak=40cisco....@dmarc.ietf.org; lsr@ietf.org
Cc: draft-ietf-lsr-flex-algo-bw-con.auth...@ietf.org
Subject: Re: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-bw-con-01.txt
[External Email. Be cautious of content]
Speaking as WG member:
I agree with Les. The Generic Metric MUST be advertised as an ASLA for
usage in Flex Algorithm. Additionally, it may be advertised as a
sub-TLV in IS- IS link TLVs. However, the latter encoding really
shouldn't be used for new applications (at least that is my reading of RFC
8919).
For OSPF, I'd certainly hope one wouldn't originate additional LSAs
when an ASLA can support the legacy applications with the ASLA mask.
Thanks,
Acee
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