Ron,
the problem in hand is whether Generic Metric should be defined as an
application specific attribute or not. I have explained several times
why making it application specific makes sense and also provided
examples of other metrics that are defined as application specific (TE
metric, Delay). There also seems to be sufficient support from the WG to
make Generic Metric an application specific link attribute.
If Generic Metric is defined as an application specific attribute, it
MUST be advertised in ASLA and only ASLA advertisement MUST be used by
flex-algo application.
The discussion about application specific nature of Generic Metric is
orthogonal to what draft-ietf-lsr-flex-algo-17 says.
If you feel the text in draft-ietf-lsr-flex-algo-17 needs to be
improved, we can do that once the discussion about the Generic Metric
being application specific or not is closed.
thanks,
Peter
On 27/07/2021 19:32, Ron Bonica wrote:
Peter,
I agree that we will need to update the flexago draft. But before we do that,
can you explain why we need to maintain mandatory use of ASLA?
AFAIKS, by their nature, some attributes are generic while others are
application specific. For example, a link's total physical bandwidth is
generic, by nature. It will always be the same for all applications. By
contrast, the amount of bandwidth available to a specific application is
application specific, by nature. It can be different for each application.
Ron
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-----Original Message-----
From: Peter Psenak <[email protected]>
Sent: Monday, July 26, 2021 2:45 PM
To: Ron Bonica <[email protected]>; Acee Lindem (acee) <[email protected]>;
Les Ginsberg (ginsberg) <[email protected]>; Shraddha Hegde <[email protected]>;
[email protected]; [email protected]
Cc: [email protected]
Subject: Re: draft-ietf-lsr-flex-algo-17 (was: [Lsr] I-D Action:
draft-ietf-lsr-flex-algo-bw-con-01.txt)
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Hi Ron,
On 26/07/2021 20:30, Ron Bonica wrote:
Peter,
I think that we are using the term "link attribute" differently. IMO, a link
attribute is any attribute of a link, regardless of whether it is advertised in the fixed
portion of a link advertisement or in a TLV.
Are you assuming otherwise? If so, why?
when we are talking about the advertisement of the link attributes, we are
talking about something that is advertised separately and optionally, not
something that is part of the fixed portion of the link advertisement.
If that is not clear, I can make that statement in the flex-algo draft, but
that would not remove the mandatory usage of the ASLA for the
(optional) attributes.
thanks,
Peter
Ron
Juniper Business Use Only
-----Original Message-----
From: Peter Psenak <[email protected]>
Sent: Monday, July 26, 2021 1:31 PM
To: Ron Bonica <[email protected]>; Acee Lindem (acee)
<[email protected]>; Les Ginsberg (ginsberg)
<[email protected]>; Shraddha Hegde <[email protected]>;
[email protected]; [email protected]
Cc: [email protected]
Subject: Re: draft-ietf-lsr-flex-algo-17 (was: [Lsr] I-D Action:
draft-ietf-lsr-flex-algo-bw-con-01.txt)
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Hi Ron,
On 26/07/2021 18:36, Ron Bonica wrote:
Acee,
We may also need to clean up an inconsistency in draft-ietf-lsr-flex-algo-17.
Section 12 of that document says:
" 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],
unless, in the case of IS-IS, the L-Flag is set in the ASLA
advertisement. If the L-Flag is set, as defined in [RFC8919]
Section 4.2 subject to the constraints discussed in Section 6 of the
[[RFC8919], then legacy advertisements are to be used instead. "
However, Flex-Algorithm calculations include the IGP metric.
IGP metric is not advertised as a link attribute, it is part of the fixed
portion of the link advertisement. So the above text is not affecting the usage
if the IGP metric.
thanks,
Peter
Ron
Juniper Business Use Only
-----Original Message-----
From: Acee Lindem (acee) <[email protected]>
Sent: Friday, July 23, 2021 10:13 AM
To: Ron Bonica <[email protected]>; Les Ginsberg (ginsberg)
<[email protected]>; Shraddha Hegde <[email protected]>;
[email protected]; Peter Psenak (ppsenak) <[email protected]>;
[email protected]
Cc: [email protected]
Subject: Re: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-bw-con-01.txt
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Hi Ron,
So perhaps, generic metric is not a legacy advertisement as strictly defined.
However, we don't want to go down the path of treating new attributes in the
same manner as legacy attributes. It seems the discussion is progressing and
hopefully we will have a resolution.
Thanks,
Acee
On 7/22/21, 1:28 PM, "Ron Bonica" <[email protected]> wrote:
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 <[email protected]> On Behalf Of Acee Lindem (acee)
Sent: Tuesday, July 20, 2021 1:21 PM
To: Les Ginsberg (ginsberg) <[email protected]>; Shraddha
Hegde <[email protected]>; [email protected];
[email protected]; [email protected]
Cc: [email protected]
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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