Hi,
I'm the co-author of this draft and I have tried to convince the rest of
the co-authors that encoding the new Generic Metric sub-TLV only as a
application independent value is wrong. Unfortunately, my efforts have
failed. As a result, although unwillingly, I have to express my opinions
here and let the WG decide.
1) The usage of the Generic Metric sub-TLV is likely going to be
associated with the applications, Flex-algo being the first one. Generic
Metric sub-TLV can not be used by IGP's native calculation. So having
Generic Metric being encoded only in legacy TLV does not make much sense.
2) TE-metric is defined as application specific attribute by
RFC 8919/8920 and can be advertised in ASLA. The application specific
value advertisement of TE-metric has been already proved in the field.
Generic Metric is semantically very similar to TE-metric, so I see no
reason why application specific encoding should not be supported.
3) Flex-algo specification mandates the usage of the ASLA attributes and
all of the attributes that we are using for flex-algo so far are encoded
in ALSA. Encoding the Generic Metric outside of ALSA violates that
principle.
4) RFC 8919/8920 violation brought by Les below.
thanks,
Peter
On 13/07/2021 17:39, Les Ginsberg (ginsberg) wrote:
Draft authors -
I note that the new version has altered the advertisement of the Generic Metric
sub-TLV so that it is no longer supported in the ASLA sub-TLV.
This is in direct violation of RFC 8919/8920.
For example, https://www.rfc-editor.org/rfc/rfc8919.html#section-6.1 states:
"New applications that future documents define to make use of the advertisements
defined in this document MUST NOT make use of legacy advertisements."
Flex-algo is a "new application" in the scope of these RFCs.
Please correct this error.
Thanx.
Les
-----Original Message-----
From: Lsr <[email protected]> On Behalf Of [email protected]
Sent: Monday, July 12, 2021 9:12 AM
To: [email protected]
Cc: [email protected]
Subject: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-bw-con-01.txt
A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Link State Routing WG of the IETF.
Title : Flexible Algorithms: Bandwidth, Delay, Metrics and
Constraints
Authors : Shraddha Hegde
William Britto A J
Rajesh Shetty
Bruno Decraene
Peter Psenak
Tony Li
Filename : draft-ietf-lsr-flex-algo-bw-con-01.txt
Pages : 27
Date : 2021-07-12
Abstract:
Many networks configure the link metric relative to the link
capacity. High bandwidth traffic gets routed as per the link
capacity. Flexible algorithms provides mechanisms to create
constraint based paths in IGP. This draft documents a generic metric
type and set of bandwidth related constraints to be used in Flexible
Algorithms.
The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-lsr-flex-algo-bw-con/
There is also an htmlized version available at:
https://datatracker.ietf.org/doc/html/draft-ietf-lsr-flex-algo-bw-con-01
A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-ietf-lsr-flex-algo-bw-con-01
Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/
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