Flex-algo model for IGP #550

vivek-ilangovan · 2022-01-04T11:02:15Z

Support for IGP Flexible algorithms RFC9350

The change proposes model for following

Definition of flexible algorithm
Advertising of flexible algorithm definition in IS-IS or just participation of IS-IS node in flexible algorithm
Advertisement of a prefix-segment associated with a flexible-algorithm in IS-IS

Flex-algorithm is keyed by a name. Attributes of flex-algorithms can be defined under /network-instances/network-instance/flex-algorithms

        +--rw oc-flexalgo:flex-algorithm
           +--rw oc-flexalgo:flex-algorithm-definition
           |  +--rw oc-flexalgo:algorithm* [flex-algo-id]
           |     +--rw oc-flexalgo:flex-algo-id    -> ../config/flex-algo-id
           |     +--rw oc-flexalgo:config
           |     |  +--rw oc-flexalgo:flex-algo-id             flex-algo-id
           |     |  +--rw oc-flexalgo:flex-algo-name?          string
           |     |  +--rw oc-flexalgo:flex-algo-description?   string
           |     |  +--rw oc-flexalgo:metric-type?             flex-algo-metric-type
           |     |  +--rw oc-flexalgo:calc-type?               flex-algo-calc-type
           |     |  +--rw oc-flexalgo:priority?                uint8
           |     |  +--rw oc-flexalgo:exclude*                 -> ../../../../flex-algo-global-attributes/flex-algo-admin-groups/admin-group/admin-group-name
           |     |  +--rw oc-flexalgo:include-all*             -> ../../../../flex-algo-global-attributes/flex-algo-admin-groups/admin-group/admin-group-name
           |     |  +--rw oc-flexalgo:include-any*             -> ../../../../flex-algo-global-attributes/flex-algo-admin-groups/admin-group/admin-group-name
           |     |  +--rw oc-flexalgo:srlg-exclude*            -> ../../../../flex-algo-global-attributes/srlgs/srlg/name
           |     |  +--rw oc-flexalgo:algo-flags?              boolean
           |     +--ro oc-flexalgo:state
           |        +--ro oc-flexalgo:flex-algo-id             flex-algo-id
           |        +--ro oc-flexalgo:flex-algo-name?          string
           |        +--ro oc-flexalgo:flex-algo-description?   string
           |        +--ro oc-flexalgo:metric-type?             flex-algo-metric-t           |        +--rw oc-flexalgo:admin-group-name    -> ../config/admin-group-name
           |        +--rw oc-flexalgo:config
           |        |  +--rw oc-flexalgo:admin-group-name?   string
           |        |  +--rw oc-flexalgo:bit-position?       uint32
           |        +--ro oc-flexalgo:state
           |           +--ro oc-flexalgo:admin-group-name?   string
           |           +--ro oc-flexalgo:bit-position?       uint32
           +--rw oc-flexalgo:flex-algo-interface-attributes
              +--rw oc-flexalgo:interface* [interface-id]
                 +--rw oc-flexalgo:interface-id    -> ../config/interface-id
                 +--rw oc-flexalgo:config
                 |  +--rw oc-flexalgo:interface-id?      oc-if:interface-id
                 |  +--rw oc-flexalgo:te-metric?         uint32
                 |  +--rw oc-flexalgo:min-delay?         uint32
                 |  +--rw oc-flexalgo:srlg-membership*   -> ../../../../flex-algo-global-attributes/srlgs/srlg/name
                 |  +--rw oc-flexalgo:admin-group*       -> ../../../../flex-algo-global-attributes/flex-algo-admin-groups/admin-group/admin-group-name
                 +--ro oc-flexalgo:state
                    +--ro oc-flexalgo:interface-id?      oc-if:interface-id
                    +--ro oc-flexalgo:te-metric?         uint32
                    +--ro oc-flexalgo:min-delay?         uint32
                    +--ro oc-flexalgo:srlg-membership*   -> ../../../../flex-algo-global-attributes/srlgs/srlg/name
                    +--ro oc-flexalgo:admin-group*       -> ../../../../flex-algo-global-attributes/flex-algo-admin-groups/admin-group/admin-group-name

Once the flex-algo attributes are defined, the IGPs can participate/advertise them by using the flex-algo-name. For example in case of IS-IS the path in the model will be /network-instances/network-instance/protocols/protocol/isis/global/segment-routing/config/fad-bindings

+--rw isis
|  +--rw global
...
             |  |  +--rw segment-routing
             |  |  |  +--rw config
             |  |  |  |  +--rw enabled?   boolean
             |  |  |  |  +--rw srgb?      -> ../../../../../../../segment-routing/srgbs/srgb/config/local-id
             |  |  |  |  +--rw srlb?      -> ../../../../../../../segment-routing/srlbs/srlb/config/local-id
             |  |  |  +--ro state
             |  |  |  |  +--ro enabled?   boolean
             |  |  |  |  +--ro srgb?      -> ../../../../../../../segment-routing/srgbs/srgb/config/local-id
             |  |  |  |  +--ro srlb?      -> ../../../../../../../segment-routing/srlbs/srlb/config/local-id
             |  |  |  |  +--rw flex-algorithm-bindings
             |  |  |  |     +--rw flex-algorithm-binding* [flex-algo-id]
             |  |  |  |        +--rw flex-algo-id    -> ../config/flex-algo-id
             |  |  |  |        +--rw config
             |  |  |  |        |  +--rw flex-algo-id?   uint8
             |  |  |  |        |  +--rw isis-level?     oc-isis-types:level-type
             |  |  |  |        |  +--rw advertised?     boolean
             |  |  |  |        |  +--rw participate?    boolean
             |  |  |  |        +--ro state
             |  |  |  |           +--ro flex-algo-id?   uint8
             |  |  |  |           +--ro isis-level?     oc-isis-types:level-type
             |  |  |  |           +--ro advertised?     boolean
             |  |  |  |           +--ro participate?    booleans

IGPs can advertise prefix-segments with an associated flex-algo by using the flex-algo-name. flex-algo-prefix-sids container is added for associating prefix with a flex-algo segment. Currently only isis uses this container and the path is /network-instances/network-instance/protocols/protocol/isis/interfaces/interface/levels/level/afi-safi/af/segment-routing/flex-algo-prefix-sids

+--rw isis
|  +--rw global
...
|  +--rw interfaces
|     +--rw interface* [interface-id]
...
|        +--rw levels
|        |  +--rw level* [level-number]
|        |     +--rw level-number            -> ../config/level-number
...
 |        |     +--rw afi-safi
 |        |     |  +--rw af* [afi-name safi-name]
...
 |        |     |     +--rw segment-routing
 |        |     |        +--rw prefix-sids
 |        |     |        |  +--rw prefix-sid* [prefix]
 |        |     |        |     +--rw prefix    -> ../config/prefix
 |        |     |        |     +--rw config
 |        |     |        |     |  +--rw prefix?          inet:ip-prefix
 |        |     |        |     |  +--rw sid-id?          oc-srt:sr-sid-type
 |        |     |        |     |  +--rw label-options?   enumeration
 |        |     |        |     +--ro state
 |        |     |        |        +--ro prefix?          inet:ip-prefix
 |        |     |        |        +--ro sid-id?          oc-srt:sr-sid-type
 |        |     |        |        +--ro label-options?   enumeration
 |        |     |        |        +--rw flex-algo-prefix-sids
 |        |     |        |        |  +--rw flex-algo-prefix-sid* [prefix flex-algo-id]
 |        |     |        |        |     +--rw prefix          -> ../config/prefix
 |        |     |        |        |     +--rw flex-algo-id    -> ../config/flex-algo-id
 |        |     |        |        |     +--rw config
 |        |     |        |        |     |  +--rw prefix?         inet:ip-prefix
 |        |     |        |        |     |  +--rw flex-algo-id?   uint8
 |        |     |        |        |     |  +--rw sid-id?         oc-srt:sr-sid-type
 |        |     |        |        |     +--ro state
 |        |     |        |        |        +--ro prefix?         inet:ip-prefix
 |        |     |        |        |        +--ro flex-algo-id?   uint8
 |        |     |        |        |        +--ro sid-id?         oc-srt:sr-sid-type

This matches the config model used in eos: https://eos.arista.com/eos-4-27-0f/is-is-flexible-algorithm/
We can configure flex algo definition under router traffic-engineering. This will translate to the path /network-instances/network-instance/flex-algorithms in the yang model

router traffic-engineering
   flex-algo
      flex-algo 128 HFT
      priority 85
      color 47
      metric min-delay
      administrative-group include all 0,3,5 include any 2,4,6 exclude 7-15
      srlg exclude flag marea warf 101 680 880 17

The IS-IS can make use of this definition to either advertise it or it can just participate in the algorithm. This translates to the /network-instances/network-instance/protocols/protocol/isis/global/segment-routing/config/fad-bindings

router isis Amun
   ...
   segment-routing mpls
      flex-algo HFT level-1 advertised

IS-IS can advertise prefix-segments associated with a particular flex algorithm. In EOS, this can be configured under interface mode. This translates to this yang path: /network-instances/network-instance/protocols/protocol/isis/interfaces/interface/levels/level/afi-safi/af/segment-routing/flex-algo-prefix-sids

[no | default] node-segment (ipv4|ipv6) index <value> [flex-algo <name>]

Other vendors configuration model looks similar:

Cisco: https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k-r6-6/segment-routing/configuration/guide/b-segment-routing-cg-asr9000-66x/b-segment-routing-cg-asr9000-66x_chapter_01111.html

Junos: https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/topic-map/infocus-isis-flex-algo-sr.html

Nokia: https://infocenter.nokia.com/public/7750SR217R1A/index.jsp?topic=%2Fcom.nokia.Segment_Routing_and_PCE_User_Guide_21.7.R1%2Fconfiguring_flexible_algorithms.html

…l associate flex-algo sid to a prefix

OpenConfigBot · 2022-01-04T11:08:14Z

Compatibility Report for commit b710383:
⛔ pyangbind@23a7a0d

…d state and in turn it was used in config and state containers causing lint errors

…tributes

…e to "Openconfig working group" that is used in other places. Change the description to fad advertisement to something meaningful instead of a question

vivek-ilangovan · 2022-02-03T06:05:58Z

Somehow the goyang/ygot is failing and it does not seem to be because of this PR. I have no idea how to make it pass!

Sample failure log:

/go/bin/generator -output_file=/go/src/aft.openconfig-aft//oc.go -path=/workspace/release/models,/workspace/third_party/ietf -package_name=exampleoc -generate_fakeroot -fakeroot_name=device -compress_paths=true -shorten_enum_leaf_names -trim_enum_openconfig_prefix -typedef_enum_with_defmod -enum_suffix_for_simple_union_enums -exclude_modules=ietf-interfaces -generate_rename -generate_append -generate_getters -generate_leaf_getters -generate_delete -annotations -generate_simple_unions -list_builder_key_threshold=3 /workspace/release/models/network-instance/openconfig-network-instance.yang /workspace/release/models/aft/openconfig-aft-network-instance.yang

package aft.openconfig-aft: no Go files in /go/src/aft.openconfig-aft

dplore · 2022-06-18T02:22:43Z

@vivek-ilangovan you should be able to correct the issue by merging your PR with the latest copy of the master branch. Note there are some conflicts to be resolved

…l associate flex-algo sid to a prefix

…d state and in turn it was used in config and state containers causing lint errors

…tributes

…e to "Openconfig working group" that is used in other places. Change the description to fad advertisement to something meaningful instead of a question

…cremented the openconfig-network-instance.yang's version and the former is a submodule of the latter

F0620 11:25:43.365961 7379 generator.go:374] ERROR Generating GoStruct Code: key flex-algo-name had a leafref key (/openconfig-network-instance/network-instances/network-instance/protocols/protocol/isis/global/segment-routing/config/fad-bindings/fad-binding/flex-algo-name) in dir algorithm that did not exist ([ network-instances network-instance flex-algorithms algorithm name]), key flex-algo-name had a leafref key (/openconfig-network-instance/network-instances/network-instance/protocols/protocol/isis/global/segment-routing/state/fad-bindings/fad-binding/flex-algo-name) in dir algorithm that did not exist ([ network-instances network-instance flex-algorithms algorithm name]) Use a string for now

…igp-top fad-bindings itself should have config and status for the key to be present and it will not be good to have fad config and status inside sr-igp-config

rgwilton · 2023-05-04T13:00:20Z

Hi,

Proxying some comments on this model from an internal expert (and author of RFC 9350):

Flex-algo affinities are encoded using ASLA, which is different to
affinities used for MPLS TE. As such referring to some TE related config
does not seem to be correct. The mapping for the flex-algo ASLA affinity
bits should be independent of the TE affinity mapping.
Enabling flex-algo per level - I'm not sure how useful that is and
what value does it bring?
They have defined the association between the interface's prefix and
flex-algo specific SIDs. That works for the SR-MPLS. In SRv6 and IP
flex-algo there are no SIDs, the prefix itself is bound to the flex-algo.

Do the YANG tree structures at the top of this review still represent the proposed configuration?

Thanks,
Rob

dplore · 2023-05-04T15:12:13Z

Last call for additional comments, to be merged on May 28th.

- Added new global and interface specific attributes for flex-algo and detach it from TE attributes

Also change fad-bindings to flex-algo-bindings to make it clear

vivek-ilangovan · 2023-05-09T14:50:22Z

Hi @rgwilton

Thanks for the comments

Flex-algo affinities are encoded using ASLA, which is different to
affinities used for MPLS TE. As such referring to some TE related config
does not seem to be correct. The mapping for the flex-algo ASLA affinity
bits should be independent of the TE affinity mapping.

Makes sense. I have created a new flex-algo-global-attributes and flex-algo-interface-attributes and referring to that in the flex-algo definition. The attributes are mostly copied from the mpls container
@gvandeve can you please help review this part again where I have added the attributes to flex-algorithms container now.

Enabling flex-algo per level - I'm not sure how useful that is and
what value does it bring?

Arista EOS supports assigning different flex-algo to different levels. So I would like to retain it. Other vendors can probably set the level as level-1-2 in case they do not have that support?

They have defined the association between the interface's prefix and
flex-algo specific SIDs. That works for the SR-MPLS. In SRv6 and IP
flex-algo there are no SIDs, the prefix itself is bound to the flex-algo.

I thought of initially supporting the SR-MPLS flex-algo segment for now. Is it ok to add the support for srv6 flex-algo and ip flex-algo later?

Do the YANG tree structures at the top of this review still represent the proposed configuration?

I have updated now with the suggested comments.

Thanks,
-Vivek

release/models/flex-algo/openconfig-flexalgo.yang

ppsenak · 2023-05-11T09:09:07Z

release/models/flex-algo/openconfig-flexalgo.yang

+      description
+        "list of references to named shared risk link groups that the
+        interface belongs to.";
+    }


you need delay metric as well.

That is true. Few implementation allow for dynamic computation of min-delay and few allows a static configuration. I am going to skip this for now and add it in next iteration if that is ok?

release/models/segment-routing/openconfig-segment-routing.yang

…lex-algo has become optional module

…flex-algo module is optional

…iner to avoid the error: "List interface has a duplicate name when the parent container flex-algo-interface-attributes is removed."

vivek-ilangovan · 2023-06-26T11:39:07Z

@dplore just wanted to check with you if this is in a state to be accepted

dplore · 2023-07-07T00:02:05Z

We will discuss at OC Operators meeting on July 11, 2023

…where

vivek-ilangovan · 2023-07-14T15:15:45Z

We will discuss at OC Operators meeting on July 11, 2023

Thanks for discussing about this PR!

dplore · 2023-07-14T16:31:03Z

Thanks for making the flex algo ID the key, this seems appropriate.

Are there any well known / rfc defined flexalgo ID’s? I didn't see any at the IANA registry but I am not sure I am looking in the right place.

dplore · 2023-07-14T23:25:35Z

/gcbrun

vivek-ilangovan · 2023-07-17T05:54:24Z

I do not think so there are any standard/defined flex-algo ids. AFAIK all ids in the valid range 128-255 are user definable

dplore · 2023-07-18T17:39:38Z

/gcbrun

dplore · 2023-07-18T18:23:54Z

@vivek-ilangovan can you please rebase your fork with the master branch? This should fix the CI checks.

See #917 for example. I can merge #917 instead and refer to this PR but the history would be cleaner if you can rebase this PR.

vivek-ilangovan · 2023-07-19T05:18:53Z

@vivek-ilangovan can you please rebase your fork with the master branch? This should fix the CI checks.

See #917 for example. I can merge #917 instead and refer to this PR but the history would be cleaner if you can rebase this PR.

@dplore I probably did what you asked. Can you check if this looks ok?

dplore · 2023-07-26T21:06:40Z

Thank you very much for the contribution @vivek-ilangovan and reviewers @gvandeve, @rgwilton, @ppsenak and @s19nal. This was a big effort!

vivek-ilangovan added 5 commits December 20, 2021 17:32

Add flex-algo model

c948cbb

Associate the flex-algo binding to segment-routing

3957505

Add flex-algo-prefix-sids container to sr-igp-interface-top. This wil…

bfbcdd7

…l associate flex-algo sid to a prefix

Add .spec.yml for the flex-algo path

0dde696

Remove Arista specific copyright info, change revision.

f16f9ca

vivek-ilangovan and others added 6 commits January 4, 2022 17:31

Add proper revisions. Fix fad-bindings as it contained both config an…

47528f6

…d state and in turn it was used in config and state containers causing lint errors

Merge branch 'master' into master

6f9829b

Make fad-bindings container as we cannot have list with other leaf at…

e46c58f

…tributes

Merge branch 'master' of https://github.com/vivek-ilangovan/public

4f502da

Remove mention of Arista from organization and contact info and chang…

02be96e

…e to "Openconfig working group" that is used in other places. Change the description to fad advertisement to something meaningful instead of a question

Remove trailing whitespace

e9c6ad2

vivek-ilangovan added 16 commits June 20, 2022 16:07

Add flex-algo model

89b718d

Associate the flex-algo binding to segment-routing

d55ff90

Add flex-algo-prefix-sids container to sr-igp-interface-top. This wil…

a305a7f

…l associate flex-algo sid to a prefix

Add .spec.yml for the flex-algo path

3177b04

Remove Arista specific copyright info, change revision.

8071e69

Add proper revisions. Fix fad-bindings as it contained both config an…

97832da

…d state and in turn it was used in config and state containers causing lint errors

Make fad-bindings container as we cannot have list with other leaf at…

2f70c4d

…tributes

Remove mention of Arista from organization and contact info and chang…

fd6e496

…e to "Openconfig working group" that is used in other places. Change the description to fad advertisement to something meaningful instead of a question

Remove trailing whitespace

0433a41

Merge branch 'openconfig-master'

48548fb

Increment version number

3349a40

Increment version of openconfig-network-instance-l2.yang as I have in…

8a85e2e

…cremented the openconfig-network-instance.yang's version and the former is a submodule of the latter

Revert accidental change because of a merge error

25250ea

Remove whitespace

bcc17aa

Pull out fad-bindings out of sr-igp-config and instead move it to sr-…

7a0c918

…igp-top fad-bindings itself should have config and status for the key to be present and it will not be good to have fad config and status inside sr-igp-config

dplore added the last-call PR that is in final review before merging. label May 4, 2023

Address review comments by @dplore

c29b453

vivek-ilangovan requested a review from a team as a code owner May 9, 2023 13:09

vivek-ilangovan and others added 3 commits May 9, 2023 18:41

Merge branch 'master' into master

6b159f6

Address comments by rgwilton

d685f35

- Added new global and interface specific attributes for flex-algo and detach it from TE attributes

Fix typo

f341878

Also change fad-bindings to flex-algo-bindings to make it clear

ppsenak reviewed May 11, 2023

View reviewed changes

vivek-ilangovan added 6 commits May 23, 2023 21:10

Address review comments by @ppsenak

dabd7c8

Fix leaf ref to flex-algo-name from segment-routing modul, now that f…

dc2bd71

…lex-algo has become optional module

Fix leaf ref in segment-routing module to flex-algo module, now that …

4950875

…flex-algo module is optional

Containerize flex-algo attributes inside a new "flex-algorithm" conta…

85c52cc

…iner to avoid the error: "List interface has a duplicate name when the parent container flex-algo-interface-attributes is removed."

Add description to new container

6b85f7c

Fix revision date

73f7c24

Address comment: Make flex-algo-name optional. Use flex-algo-id every…

386e832

…where

dplore approved these changes Jul 18, 2023

View reviewed changes

Merge branch 'openconfig:master' into master

b710383

dplore merged commit e84d592 into openconfig:master Jul 26, 2023
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Flex-algo model for IGP #550

Flex-algo model for IGP #550

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Flex-algo model for IGP #550

Flex-algo model for IGP #550

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