Add MANUAL proxy-arp mode and manual-ip-prefix leaf-list to openconfig-if-ip IPv4 mode

[jsingh2-c]

…penconfig-if-ip model

Change Scope

• [This change extends the openconfig-if-ip model to support selective (manual) IPv4 proxy ARP behavior used by existing implementations, where the system responds to ARP requests only for explicitly configured IPv4 prefixes. A new manual-ip-prefixes list is added under the /ipv4/proxy-arp subtree, placed alongside the existing config and state containers. Each manual-ip-prefix entry is keyed by IPv4 prefix and models both configuration and operational state, following standard OpenConfig list and config/state patterns. The mode enumeration under /proxy-arp/config is extended with a new value, MANUAL. In MANUAL mode, proxy ARP responses are generated only when the ARP target IPv4 address matches one of the prefixes configured under manual-ip-prefixes.]
• [This change is fully backward compatible:
  Existing enum values (DISABLE, REMOTE_ONLY, ALL) remain unchanged.
  Existing clients not using MANUAL mode are unaffected.
  The new list is optional and has no operational effect unless mode=MANUAL.]

Platform Implementations

• Implementation A: Ciena 6500
  The platform requires operator‑controlled manual proxy ARP for deployment scenarios.
  The implementation uses Linux kernel proxy ARP + NFtables filtering.
  [link to documentation](Vendor documentation for this feature is currently internal and not publicly
  shareable prior to feature completion. The externally visible behavior is fully described by the YANG model semantics.)
• Implementation B: OpenROADM Proxy ARP Model
  OpenROADM models a similar structure for proxy ARP entries as “proxy‑subnet” using CIDR prefixes, which our model aligns with conceptually. link to documentation

Tree View

[Next, cut and paste the relevant portion of the tree with enough context for reviewers to quickly understand the change.]

 module: openconfig-if-ip
    augment /oc-if:interfaces/oc-if:interface/oc-if:subinterfaces/oc-if:subinterface:
     +--rw ipv4
        +--rw addresses
        |  +--rw address* [ip]
        |     +--rw ip        -> ../config/ip
        |     +--rw config
        |     |  +--rw ip?              oc-inet:ipv4-address
        |     |  +--rw prefix-length?   uint8
        |     |  +--rw type?            ipv4-address-type
        |     +--ro state
        |     |  +--ro ip?              oc-inet:ipv4-address
        |     |  +--ro prefix-length?   uint8
        |     |  +--ro type?            ipv4-address-type
        |     |  +--ro origin?          ip-address-origin
        |     +--rw vrrp
        |        +--rw vrrp-group* [virtual-router-id]
        |           +--rw virtual-router-id     -> ../config/virtual-router-id
        |           +--rw config
        |           |  +--rw virtual-router-id?        uint8
        |           |  +--rw virtual-address*          oc-inet:ip-address
        |           |  +--rw priority?                 uint8
        |           |  +--rw preempt?                  boolean
        |           |  +--rw preempt-delay?            uint16
        |           |  +--rw accept-mode?              boolean
        |           |  +--rw advertisement-interval?   uint16
        |           +--ro state
        |           |  +--ro virtual-router-id?        uint8
        |           |  +--ro virtual-address*          oc-inet:ip-address
        |           |  +--ro priority?                 uint8
        |           |  +--ro preempt?                  boolean
        |           |  +--ro preempt-delay?            uint16
        |           |  +--ro accept-mode?              boolean
        |           |  +--ro advertisement-interval?   uint16
        |           |  +--ro current-priority?         uint8
        |           +--rw interface-tracking
        |              +--rw config
        |              |  +--rw track-interface*      -> /oc-if:interfaces/interface/name
        |              |  +--rw priority-decrement?   uint8
        |              +--ro state
        |                 +--ro track-interface*      -> /oc-if:interfaces/interface/name
        |                 +--ro priority-decrement?   uint8
        +--rw proxy-arp
        |  +--rw config
        |  |  +--rw mode?   enumeration
        |  +--ro state
-       |     +--ro mode?   enumeration
+       |  |  +--ro mode?   enumeration
+       |  +--rw manual-ip-prefixes
+       |     +--rw manual-ip-prefix* [prefix]
+       |        +--rw prefix    -> ../config/prefix
+       |        +--rw config
+       |        |  +--rw prefix?   oc-inet:ipv4-prefix
+       |        +--ro state
+       |           +--ro prefix?   oc-inet:ipv4-prefix
        +--rw neighbors
        |  +--rw neighbor* [ip]
        |     +--rw ip        -> ../config/ip
        |     +--rw config
        |     |  +--rw ip?                   oc-inet:ipv4-address
        |     |  +--rw link-layer-address    oc-yang:phys-address
        |     +--ro state
        |        +--ro ip?                   oc-inet:ipv4-address
        |        +--ro link-layer-address    oc-yang:phys-address
        |        +--ro origin?               neighbor-origin

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[gemini-code-assist]

Code Review

This pull request updates the OpenConfig IPv4 proxy ARP model to version 3.10.0, introducing a 'MANUAL' mode and a corresponding 'manual-ip-prefixes' list for explicit prefix configuration. The review feedback suggests improving the clarity of the documentation by explicitly referring to 'proxy ARP mode' in the descriptions of the new configuration elements to ensure consistency and avoid ambiguity.

[dplore]

Please add more description in the yang model of what the MANUAL mode is. Is this a filter of which client IP address the device will respond to ARP requests when doing proxy-ARP?

The Ciena link only goes to the main website. Please add a link to documentation describing the feature being added.

[jsingh2-c]

Please add more description in the yang model of what the MANUAL mode is. Is this a filter of which client IP address the device will respond to ARP requests when doing proxy-ARP?

The Ciena link only goes to the main website. Please add a link to documentation describing the feature being added.

Updated the Change Scope section to clearly explain the rationale for modeling manual (prefix-based) proxy ARP behavior and clarified MANUAL mode semantics.
Updated the Platform Implementations section to explain the reference implementation and note that vendor documentation is currently internal, with model behavior fully defined by the YANG descriptions.

[jsingh2-c]

Rebased the branch onto the latest upstream master.
Updated the YANG descriptions to clarify MANUAL proxy ARP semantics (including explicit target IPv4 address matching) and updated the PR description to better describe the rationale and reference implementation context. Thanks for the review.

[ElodinLaarz]

/gcbrun

[OpenConfigBot]

No major YANG version changes in commit 5d99115

[ElodinLaarz]

Reviewed at the OC Operators Meeting on May 5th, 2026:

Seems reasonable.

Failing whitespace CI check can be fixed. Will move to last-call if there are no objections in 2 weeks.