Interface MTU type adjustments and description updates

release/models/interfaces/openconfig-if-ip.yang

@@ -45,29 +45,40 @@ module openconfig-if-ip {
     Section 4.c of the IETF Trust's Legal Provisions Relating
     to IETF Documents (http://trustee.ietf.org/license-info).";
 
-  oc-ext:openconfig-version "3.9.0";
+  oc-ext:openconfig-version "3.9.1";
 
-    revision "2025-06-20" {
+  revision "2026-04-05" {
     description
-      "Add IPv6 Router Advertisement Options for DNS Configuration (RDNSS) RFC 8106.";
-      reference "3.9.0";
+      "Update IPv6 mtu reference from obsoleted RFC 2460 to RFC 8200.
+      Add RFC 2675 reference for jumbogram support justifying the uint32
+      type.";
+    reference "3.9.1";
   }
 
-    revision "2025-06-20" {
+  revision "2025-06-20" {
     description
-      "Add model for support of URPF source address validation through network-instance different then one used for destination lookup";
-      reference "3.8.0";
+      "Add IPv6 Router Advertisement Options for DNS Configuration
+      (RDNSS) RFC 8106.";
+    reference "3.9.0";
+  }
+
+  revision "2025-06-20" {
+    description
+      "Add model for support of URPF source address validation through
+      network-instance different then one used for destination lookup";
+    reference "3.8.0";
   }
 
   revision "2025-05-12" {
     description
       "Add model for support of URPF source address verification";
-      reference "3.7.0";
+    reference "3.7.0";
   }
 
   revision "2024-05-28" {
     description
-      "Add gratuitous-arp-accepted for IPv4 and unsolicited-na-accepted for IPv6.";
+      "Add gratuitous-arp-accepted for IPv4 and unsolicited-na-accepted
+      for IPv6.";
     reference "3.6.0";
   }
 
@@ -83,10 +94,10 @@ module openconfig-if-ip {
     reference "3.5.0";
   }
 
-revision "2023-06-30" {
+  revision "2023-06-30" {
     description
-      "Deprecate IPv6 router advertisment config suppress leaf and add config
-      mode leaf.";
+      "Deprecate IPv6 router advertisment config suppress leaf and add
+      config mode leaf.";
     reference "3.4.0";
   }
 
@@ -134,9 +145,8 @@ revision "2023-06-30" {
 
   revision "2017-07-14" {
     description
-      "Added Ethernet/IP state data; Add dhcp-client;
-      migrate to OpenConfig types modules; Removed or
-      renamed opstate values";
+      "Added Ethernet/IP state data; Add dhcp-client; migrate to
+      OpenConfig types modules; Removed or renamed opstate values";
     reference "2.0.0";
   }
 
@@ -524,13 +534,13 @@ revision "2023-06-30" {
      units octets;
      description
        "The size, in octets, of the largest IPv4 packet that the
-        interface will send and receive.
+       interface will send and receive.
 
-        The server may restrict the allowed values for this leaf,
-        depending on the interface's type.
+       The server may restrict the allowed values for this leaf,
+       depending on the interface's type.
 
-        If this leaf is not configured, the operationally used MTU
-        depends on the interface's type.";
+       If this leaf is not configured, the operationally used MTU
+       depends on the interface's type.";
      reference
        "RFC 791: Internet Protocol";
     }
@@ -651,8 +661,9 @@ revision "2023-06-30" {
         If this leaf is not configured, the operationally used MTU
         depends on the interface's type.";
       reference
-        "RFC 2460: Internet Protocol, Version 6 (IPv6) Specification
-                  Section 5";
+        "RFC 8200: Internet Protocol, Version 6 (IPv6) Specification
+                   Section 5
+         RFC 2675: IPv6 Jumbograms";
     }
 
     leaf dup-addr-detect-transmits {

release/models/interfaces/openconfig-if-types.yang

@@ -0,0 +1,57 @@
+module openconfig-if-types {
+
+  yang-version "1";
+
+  // namespace
+  namespace "http://openconfig.net/yang/interfaces/types";
+
+  prefix "oc-ift";
+
+  // import some basic types
+  import openconfig-extensions { prefix oc-ext; }
+
+  // meta
+  organization "OpenConfig working group";
+
+  contact
+    "OpenConfig working group
+    netopenconfig@googlegroups.com";
+
+  description
+    "This module defines types and identities used in OpenConfig models
+    related to Interfaces.";
+
+  oc-ext:openconfig-version "0.1.0";
+
+  revision "2026-04-05" {
+    description
+      "Initial revision.";
+    reference "0.1.0";
+  }
+
+  // OpenConfig specific extensions for module metadata.
+  oc-ext:regexp-posix;
+  oc-ext:catalog-organization "openconfig";
+  oc-ext:origin "openconfig";
+
+  // typedef statements
+
+  typedef max-frame-size {
+    type uint32;
+    units octets;
+    description
+     "The maximum frame size in octets that may be transmitted or
+     received on an interface. For Ethernet interfaces, this value
+     includes the Ethernet header but excludes the 4-octet frame check
+     sequence (FCS) per IEEE 802.3. For non-Ethernet interface types
+     (e.g., loopback, tunnel), the value represents the maximum
+     transmission unit of the interface without Layer 2 framing overhead
+     specific to the encapsulation type.
+
+     If configured, the max-frame-size also limits the maximum frame
+     size of any child sub-interfaces. The MTU available to higher layer
+     protocols is restricted to the maximum frame payload size, and may
+     be further restricted by explicit Layer 3 or protocol specific MTU
+     configuration.";
+  }
+}

release/models/interfaces/openconfig-interfaces.yang

@@ -13,6 +13,7 @@ module openconfig-interfaces {
   import openconfig-types { prefix oc-types; }
   import openconfig-extensions { prefix oc-ext; }
   import openconfig-transport-types { prefix oc-opt-types; }
+  import openconfig-if-types { prefix oc-ift; }
 
   // meta
   organization "OpenConfig working group";
@@ -51,48 +52,54 @@ module openconfig-interfaces {
     Section 4.c of the IETF Trust's Legal Provisions Relating
     to IETF Documents (http://trustee.ietf.org/license-info).";
 
-  oc-ext:openconfig-version "3.8.1";
+  oc-ext:openconfig-version "4.0.0";
+
+  revision "2026-04-05" {
+    description
+      "Change interface mtu type from uint16 to max-frame-size (uint32)
+      typedef to support MTU values exceeding 16-bit boundaries as seen
+      on loopback and non-Ethernet interface types. Clarify L2 frame
+      size semantics in description.";
+    reference "4.0.0";
+  }
 
   revision "2026-01-06" {
-      description
-        "Fix typos in descriptions for hardware-specific and interface statistics entities.";
-      reference
-        "3.8.1";
+    description
+      "Fix typos in descriptions for hardware-specific and interface
+      statistics entities.";
+    reference "3.8.1";
   }
 
   revision "2024-12-05" {
-      description
-        "Add interface-transitions and link-transitions counters";
-      reference
-        "3.8.0";
+    description
+      "Add interface-transitions and link-transitions counters";
+    reference "3.8.0";
   }
 
   revision "2024-12-05" {
-      description
-        "Description typo for unnumbered/interface-ref/config/subinterface leaf";
-      reference
-        "3.7.2";
+    description
+      "Description typo for unnumbered/interface-ref/config/subinterface
+      leaf";
+    reference "3.7.2";
   }
 
   revision "2024-04-04" {
-      description
-        "Use single quotes in descriptions.";
-      reference
-        "3.7.1";
+    description
+      "Use single quotes in descriptions.";
+    reference "3.7.1";
   }
 
   revision "2023-11-06" {
-      description
-        "Clarify description for admin-status TESTING.";
-      reference
-        "3.7.0";
+    description
+      "Clarify description for admin-status TESTING.";
+    reference "3.7.0";
   }
 
   revision "2023-08-29" {
-      description
-        "Add augment for penalty-based additive-increase, exponential-decrease link damping algorithm.";
-      reference
-        "3.6.0";
+    description
+      "Add augment for penalty-based additive-increase,
+      exponential-decrease link damping algorithm.";
+    reference "3.6.0";
   }
 
   revision "2023-07-14" {
@@ -458,12 +465,11 @@ module openconfig-interfaces {
     }
 
     leaf mtu {
-      type uint16;
+      type oc-ift:max-frame-size;
       description
-        "Set the max transmission unit size in octets
-        for the physical interface.  If this is not set, the mtu is
-        set to the operational default -- e.g., 1514 bytes on an
-        Ethernet interface.";
+        "The maximum frame size for the physical interface. If this is
+        not set, the mtu is set to the operational default -- e.g., 1514
+        bytes on an Ethernet interface.";
     }
 
     leaf loopback-mode {