Hi Gunter,
On 06/08/2020 19:11, Van De Velde, Gunter (Nokia - BE/Antwerp) wrote:
Thanks for the clarification and fast answer.
Indeed FAD does not encode any attributes.
That was not the point I was trying to make.
. The existing description in section 5.1 indicate that legacy encoding
(RFC7810 and RFC5305) is used for link attributes. That is not correct based
upon section 11. To avoid ambiguity can an explicit reference be added for
[I-D.ietf-isis-te-app]?
well, section 5.1. is correct. The Min Unidirectional Link Delay and TE
Default metric respectively were defined in RFC7810 and RFC5305. The
fact that we advertise them in ASLA does not change their origin.
. Similar for section 5.2 where a reference to RFC7471 and RFC3630 should be
added together with explicit reference to [I-D.ietf-ospf-te-link-attr-reuse].
I'm not seeing RFC7471 and RFC3630 being reference anywhere in the draft.
Explicit reference to ASLA encodings in section 5.1 and 5.2 will avoid
confusion and avoid legacy link attribute encodings (rfc7810/5305/7471/3630)
for flex-algo.
I really do not see any relevance of FAD and ASLA. Linking these
together will be wrong.
Could in section 11 be explicit reference to (e)ag, te-metric and delay link
attributes MUST be encoded using ASLA..
Section 11 already says:
Link attribute advertisements that are to be used during Flex-
Algorithm calculation MUST use the Application Specific Link
Attribute (ASLA) advertisements defined in [I-D.ietf-isis-te-app] or
[I-D.ietf-ospf-te-link-attr-reuse].
I'm not sure what else can we say. Listing the ones we use today wold be
dangerous, because we may define additional ones later and we want the
ASLA to be mandatory for all of them.
thanks,
Peter
G/
________________________________________
From: Peter Psenak <[email protected]>
Sent: Thursday, August 6, 2020 6:37:42 PM
To: Van De Velde, Gunter (Nokia - BE/Antwerp) <[email protected]>;
[email protected] <[email protected]>
Cc: [email protected] <[email protected]>
Subject: Re: [draft-ietf-lsr-flex-algo-08] Clarification on ASLA usage for
flex-algo
Hi Gunter,
On 06/08/2020 18:31, Van De Velde, Gunter (Nokia - BE/Antwerp) wrote:
Hi Authors, All,
My understanding is that for new LSR applications we should select
either "ASLA encoding" or select "legacy encoding" for all Link attributes.
Not a mixture of both. There is a clear long term technology benefit of
using all ASLA encoding.
In draft-ietf-lsr-flex-algo-08 "Section 11: Advertisement of Link
Attributes for Flex-Algorithm" we find that use of ASLA is mandated
"
Link attribute advertisements that are to be used during Flex-
Algorithm calculation MUST use the Application Specific Link
Attribute (ASLA) advertisements defined in [I-D.ietf-isis-te-app] or
[I-D.ietf-ospf-te-link-attr-reuse].
"
This is a 'normative' instruction that link attributes MUST use ASLA
encoding.
Hence link attributes like (e)ag, te-metric and delay MUST be ASLA encoded.
Is that correct understanding?
yes, for any link attributes used for flex-algo.
If yes, it is odd that some attributes are new ASLA and some other are
non-future proof 'LEGACY' encodings
* Example#1: section 5.1 "ISIS Flexible Algorithm Definition Sub-TLV"
and section 5.2 "OSPF Flexible Algorithm Definition TLV" point
towards legacy encodings RFC7810 and RFC5305 (idnit RFC7810 is
obsoleted by RFC8570).
* Example#2: section 5.2 "OSPF Flexible Algorithm Definition TLV" the
normative references are missing
ASLA is link-attributes related (Application Specific Link Attributes).
ASLA can only be used to encode link attributes. FAD is not a link
attribute, so it can not use ASLA.
thanks,
Peter
Sections 5.1 and 5.2 should update the link attribute encoding
references to reflect ASLA encoding as specified in section 11.
The text referencing legacy encodings should be removed
G/
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