



DMSC Working Group                                                S. Sun
Internet-Draft                                                  ICT, CAS
Intended status: Standards Track                                X. Zhang
Expires: 9 August 2026                                         CNIC, CAS
                                                           February 2026


      Intent-based Agent Interconnection Protocol at Agent Gateway
                        draft-sun-zhang-iaip-00

Abstract

   This document specifies the Intent-based Agent Interconnection
   Protocol (IAIP) operating at the Agent Gateways (AG), which defines
   the interaction mechanisms between AI Agents (at the Agent Domain)
   and the AG (at the Interconnection Services Domain).  This
   specification focuses on dynamic interconnection among agents based
   on semantic intent, rather than static network addressing alone.
   This protocols defines the mechanisms for agent registration via
   capability advertisement, Gateway Validation, Intent Resolution and
   Matching, Routing Decisions and Forwarding, enabling the discovery,
   selection and dispatching of intent queries based on agent
   capabilities and task requirements at AG.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 5 August 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.






Sun & Zhang               Expires 9 August 2026                 [Page 1]

Internet-Draft                    IAIP                     February 2026


   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Problem Statement and Use Cases . . . . . . . . . . . . . . .   4
     4.1.  Limitations of Address-Based Static Interconnection . . .   4
     4.2.  Representative Use Case . . . . . . . . . . . . . . . . .   5
   5.  Function Components . . . . . . . . . . . . . . . . . . . . .   6
   6.  Protocol Overview . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Message Formats . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  Protocol Operation and Core Procedures  . . . . . . . . . . .  12
     8.1.  Illustrative Protocol Examples  . . . . . . . . . . . . .  12
       8.1.1.  Example A: Agent Registration (CAP_ADV) . . . . . . .  12
       8.1.2.  Example B: Intent Resolution Flow . . . . . . . . . .  12
       8.1.3.  Example C: Routing Feedback . . . . . . . . . . . . .  13
     8.2.  Agent Access Component (AAC) Operations . . . . . . . . .  13
       8.2.1.  Session Authentication and Integrity  . . . . . . . .  13
       8.2.2.  Ingress Validation  . . . . . . . . . . . . . . . . .  13
     8.3.  Local Capability Registry (LCR) Management  . . . . . . .  14
       8.3.1.  Profile Creation and Updates  . . . . . . . . . . . .  14
       8.3.2.  Lifecycle Maintenance . . . . . . . . . . . . . . . .  14
     8.4.  Intent Forwarding Routing Table (IFR) Decision Logic  . .  14
       8.4.1.  Candidate Retrieval . . . . . . . . . . . . . . . . .  14
       8.4.2.  Constraint-Based Filtering  . . . . . . . . . . . . .  14
       8.4.3.  Semantic Evaluation and Ranking . . . . . . . . . . .  15
       8.4.4.  Selection and Fallback  . . . . . . . . . . . . . . .  15
     8.5.  Forwarding and Loop Prevention  . . . . . . . . . . . . .  15
     8.6.  Reliability and Error Handling  . . . . . . . . . . . . .  15
     8.7.  Protocol Processing procedure at Agent Gateways . . . . .  15
   9.  Conclusions . . . . . . . . . . . . . . . . . . . . . . . . .  18
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  18
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   12. Normative References  . . . . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18







Sun & Zhang               Expires 9 August 2026                 [Page 2]

Internet-Draft                    IAIP                     February 2026


1.  Introduction

   The emergence of agentic networks marks a fundamental shift from
   static, address-based networking to semantic, intent-driven
   interactions.  Autonomous agents powered by advanced artificial
   intelligence models are capable of reasoning, planning, and executing
   tasks on behalf of users or other agents.  Interactions are
   increasingly expressed in terms of high-level objectives or natural
   language intents, rather than predefined service endpoints or static
   interfaces.

   Traditional networking and service discovery mechanisms assume that
   communication targets are identified by fixed addresses, names, or
   service identifiers.  These assumptions no longer hold in agentic
   environments, where the appropriate execution entity for a request
   may depend on semantic interpretation, contextual constraints, and
   dynamic system conditions.  As a result, routing decisions based
   solely on static addressing or preconfigured bindings are
   insufficient to support flexible and scalable agent collaboration.

   Intent-based interconnection addresses this gap by enabling the Agent
   Gateway to resolve and forward requests according to their semantic
   intent, rather than their destination address.  By decoupling request
   dispatch from rigid topology and static identifiers, intent-based
   interconnection allows autonomous agents to be dynamically
   discovered, selected, and invoked based on their advertised
   capabilities.

   This document introduces the Intent-based Agent Interconnection
   Protocol (IAIP) to provide a standardized mechanism for capability-
   based registration and validation, intent-aware discovery and routing
   at AG.  IAIP is designed to operate as an application-layer protocol
   for interconnection service domain, complementing existing transport
   and networking infrastructure without requiring changes to underlying
   transport protocols.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in <xref
   target="RFC2119"/>.

3.  Terminology

   AI Agent  An agent is a software or hardware entity with autonomous





Sun & Zhang               Expires 9 August 2026                 [Page 3]

Internet-Draft                    IAIP                     February 2026


      decision-making and execution capabilities, capable of perceiving
      the environment, acquiring contextual information, reasoning, and
      learning.

   Agent Gateway (AG)  A Functional Component in the Interconnection
      Service Domain that possesses the capbilities of agent
      registration, capbility authentication, intent resolution and
      estabilishing interconnection betweens agents.

   Intent  A declarative expression of a desired outcome.  In the
      intent-driven routing protocol, intent is represented at three
      conceptual layers:

      *  *Human Intent:*A high-level, possibly ambiguous expression
         originating from a human user or application (e.g., natural
         language input).  Human Intent is out of scope for the
         protocol.

      *  *Task Intent:*An abstract, task-oriented description that
         captures the objective of a request, independent of any
         specific agent, algorithm, or execution plan.

      *  *Intent Descriptor:*A structured, machine-interpretable
         representation of Task Intent used within IAIP for routing and
         dispatching decisions.

   Leader Agent (LA)  Agent who issues tasks and launches interactions.
      There should only be one Leader Agent in a complete task execution
      process.

   Partner Agent (PA)  Agent who accepts tasks and provides services.
      After Partner Agent receives a task from the Leader Agent, it
      executes and returns the execution result.

4.  Problem Statement and Use Cases

4.1.  Limitations of Address-Based Static Interconnection

   Existing network interconnection and gateway mechanisms are
   predominantly organized around static identifiers, such as network
   addresses, domain names, or service labels.  At the application and
   service-dispatch layer, these mechanisms assume that the
   functionality associated with a agent behind a gateway is stable,
   explicitly addressable and functionally static.  While effective for
   traditional client-server and microservice architectures, this
   assumption becomes increasingly inadequate for the dynamic
   interconnection required by agentic networks.




Sun & Zhang               Expires 9 August 2026                 [Page 4]

Internet-Draft                    IAIP                     February 2026


   First, traditional interconnection protocols provide limited support
   for expressing semantic intent.  High-level requests such as "analyze
   this dataset" or "resolve a billing issue" do not naturally
   correspond to a single predefined endpoint.  Encoding semantic
   meaning into static addresses or service names requires manual
   configuration and tight coupling between task requesters and service
   providers, which undermines flexibility and scalability.

   Second, static interconnection lacks adaptability to dynamic
   lifecycle of AI Agents.  In the Agent Domain, agents may be
   instantiated, fine-tuned, or deprecated rapidly based on
   computational load or task requirements.  Static bindings or name-
   based resolution mechanisms are generally unable to reflect real-time
   changes in agent's availability or intent-processing capacity,
   leading to service selection or routing dispatch failures.

   Third, existing protocols offer limited support for intent-aware
   resolution.  When a request arrives at the gateway without a specific
   destination address, traditional gateway have no mechanism to parse
   the intent and match it against a local registry of vector-based
   capabilities.  This behavior is misaligned with agentic workflows,
   where ambiguous or underspecified intents are common and may require
   clarification, delegation, or escalation to more generalist agents.

   These limitations motivate the need for an intent-driven
   interconnection protocol specifically at the Agent Gateway that can
   manage registration and routing based on semantic intent and
   dynamically advertised capabilities, rather than relying solely on
   fixed addresses or static identifiers.  This protocol addresses these
   challenges by transforming the gateway from a static packet forwarder
   into a semantic ingress/egress point, enabling establishing agent
   interconnection while maintaining compatibility with the
   Interconnection Service Domain.

4.2.  Representative Use Case

   The following example illustrates a typical use case of the Intent-
   based Agent Interconnection Protocol operating at the Agent Gateway.

   A Customer Service Dispatcher Agent, acting as the Leader Agent,
   transmits a user inquiry to the AG for intent resolution and service
   response.  Specialized Partner Agents (Billing, Technical Support,
   Sales) have previously registered their specific semantic domains
   with the AG.  For explicit queries like "My credit card was charged
   twice," the AG identifies a high-confidence semantic match and routes
   the request to the Billing Agent.  Upon completion, the AG relays the
   result back to the Leader Agent.  Conversely, when handling ambiguous
   inputs (e.g., "I'm having a bad experience") where semantic



Sun & Zhang               Expires 9 August 2026                 [Page 5]

Internet-Draft                    IAIP                     February 2026


   similarity scores fail to meet the required confidence threshold, the
   AG encapsulates the intent and forwards the intent to a Generalist
   Fallback Agent.  This mechanism ensures the request is constructively
   resolved via clarifying questions or human escalation, thereby
   preventing service failure.

5.  Function Components

   Figure 1 illustrates the interaction diagram between AI agent and
   Agent Gateway.

  [Agent Domain]                [Interconnection Service Domain]
     +-----------+      IAIP       +---------------+
     |  AI Agent | <-------------> | Agent Gateway | <---> [Core Router]
     +-----------+                 +---------------+

     Figure 1: Interaction Diagram between AI Agent and Agent Gateway

   To support the interaction with AI Agents, the AG MUST implement the
   following specific Functional Components within the Interconnection
   Service Domain.

   *  *Local Capability Registry (LCR):*The LCR maintains a dynamic
      database of attached Agents.  The function of LCR is to store the
      Capability Profile of each registered agent.  When an Agent sends
      the capability updating request, the LCR updates the mapping.

   *  *Agent Access Component (AAC):*The AAC serves as the termination
      point for the interconnection session between the AI Agent and the
      Agent Gateway.  The function of AAC is to manage authentication,
      maintain session lifecycle, and verify message integrity.  When an
      AI Agent initiates a connection or transmits a message, the AAC
      validates the agent's identity credentials and establishes the
      interconnection for message forwarding.

   *  *Intent Forwarding Routing Table (IFR):*The IFR serves as the
      dynamic routing decision engine within the Agent Gateway for
      forwarding intent-based requests.  Its primary function is to map
      normalized intent vectors-derived from incoming task semantics-to
      a set of eligible Partner agents.  Based on real-time capability
      matching scores, performance metrics (e.g., latency, success rate,
      and resource availability), and policy constraints, the IFR
      selects the optimal next-hop Partner agent for request forwarding.

6.  Protocol Overview

   The protocol functions in two primary phases.




Sun & Zhang               Expires 9 August 2026                 [Page 6]

Internet-Draft                    IAIP                     February 2026


   *  *Phase 1: Agent Registration & Capability Advertisement.*This
      phase establishes the trust domain and service mesh.  Both Leader
      Agents and Partner Agents MUST complete Identity Registration with
      the Agent Gateway (AG) to obtain the verifiable Agent Identity
      Code (AIC).  Following identity registration, Partner Agents (or
      agents acting in a service-provisioning role) MUST additionally
      perform Capability Advertisement to publish their functional
      profiles to the Local Capability Registry (LCR).

   *  *Phase 2: Intent-based Routing and Forwarding.*This phase
      establishes intent-based interconnection.  The Leader Agent
      submits its intent.  The AG resolves it against the LCR and IFR,
      selects suitable Partner Agents, and facilitates the connection.

   Figure 2 illustrates the updated two-stage processing pipeline
   between AI Agents and AG.



































Sun & Zhang               Expires 9 August 2026                 [Page 7]

Internet-Draft                    IAIP                     February 2026


   +--------------+ +------------------------+ +--------------+
   | Leader Agent | |     Agent Gateway      | | Partner Agent|
   |(Intent Init.)| |(Network Infrastructure)| |(Intent Exec.)|
   +------+-------+ +------------+-----------+ +------+-------+
          |                      |                      |
          | Phase 1: Identity Reg & Capability Advt.    |
          |                      |                      |
          |--(1) Identity Reg -->|                      |
          |   [ACP-IF-01]        |                      |
          |                      |<--(2) Identity Reg --|
          |                      |    [ACP-IF-01]       |
          |                      |                      |
          |                      |<--(3) Publish Cap ---|
          |                      |    [ACP-IF-06]       |
          |                      |                      |
          |                      |-->(4) Sync & Trust --|
          |                      |    [ADF / DTMgF]     |
          |                      |                      |
          | Phase 2: Intent-based Routing               |
          |                      |                      |
          |--(5) Submit Intent ->|                      |
          |   [Signed Vector]    |                      |
          |                      |                      |
          |                      |-->(6) Resolve Intent-|
          |                      |     Match ADF DB     |
          |                      |     DTMgF Filter     |
          |                      |                      |
          |                      |<--(7) Cand. List ----|
          |                      |   [Ranked + Sig]     |
          |<--(8) Verify & Select|                      |
          |                      |                      |
          |=========(9) Routing and Execution =========>|
          |        [E2E via ACP-IF-08/09]               |
          |=============================================|

                Figure 2: Two-Stage Processing Flow of IAIP

   *Phase 1: Agent Registration & Capability Advertisement*

   This stage is the prerequisite for any agent participation.  It
   involves Identity Registration (mandatory for all) and Capability
   Publication (mandatory for service providers).  The steps are as
   follows:

   *  *Step1:*Identity Registration (Leader & Partner).  Any Agent
      (whether Leader or Partner) MUST register its identity with the
      Agent Gateway using the ACP-IF-01 interface (between AIMF in the
      agent and AIMgF in the AG).  This establishes a verifiable Agent



Sun & Zhang               Expires 9 August 2026                 [Page 8]

Internet-Draft                    IAIP                     February 2026


      Identity Code (AIC) and exchanges cryptographic credentials
      required for future intent signing (Leader) or service execution
      (Partner).

   *  *Step2:*Capability Publication (Partner Agent).  The Partner Agent
      publishes a structured capability description (e.g., supported
      task types, performance bounds, resource constraints) to the Agent
      Gateway via the ACP-IF-06 interface (ADMF <-> ADMgF).  Note: If a
      Leader Agent also wishes to serve tasks, it MUST also perform this
      step.

   *  *Step3:*Synchronization to Interconnection Service Domain.  The
      Agent Gateway forwards the capability description to the Agent
      Description Management Function (ADMgF) in the Interconnection
      Service Domain.  ADMgF persists the data and synchronizes it to
      the Agent Discovery Function (ADF) for indexing.

   *  *Step4:*Trust Scope Enforcement.  The Domain Trust Management
      Function (DTMgF) applies domain federation policies to determine
      whether the registered Agent is authorized to operate within the
      specific trust domain.  Only authorized capabilities are made
      queryable via ADF.

   *Phase 2: Intent-based Routing and Forwarding*

   This stage is triggered when a registered Leader Agent submits a
   semantic intent request.  The Agent Gateway resolves and routes the
   intent to eligible Partner Agents.  The steps are as follows:

   *  *Step5:*Intent Submission.  The Leader Agent sends a signed
      semantic intent vector to the Agent Gateway.  The signature MUST
      be generated using the credentials established in Step 1.  The
      payload contains abstract task semantics.

   *  *Step6:*Intent Resolution and Candidate Matching.  The Agent
      Gateway invokes the ACP-IF-07 interface to query the ADF.  The IFR
      (Intent Forwarding Routing Table) performs semantic matching
      against the LCR, filtering based on trust scopes, and ranking
      candidates.

   *  *Step7:*Candidate Agents Return.  The Gateway returns a ranked
      list of eligible Partner Agents to the Leader Agent.

   *  *Step8:*Leader-side Verification and Selection.  The Leader Agent
      verifies the gateway's signature and selects one or more Partners
      based on local policy.





Sun & Zhang               Expires 9 August 2026                 [Page 9]

Internet-Draft                    IAIP                     February 2026


   *  *Step9:*Routing and Execution.  The Leader Agent establishes a
      direct end-to-end session with the selected Partner Agent(s) using
      ACP-IF-08 for point-to-point interaction, or ACP-IF-09 for
      grouping-mode collaboration.  All task payloads are transmitted
      over this encrypted channel.

7.  Message Formats

   This section specifies the binary structure of IAIP messages.  The
   protocol uses a Type-Length-Value (TLV) design to ensure
   extensibility.

  +--------------------------------------------------------------------+
  |                      IAIP Message (TLV-based)                      |
  +--------------------------------------------------------------------+
  |                                                                    |
  |  +-------------------+------+-----------------------------------+  |
  |  | Type              | Len  | Value                             |  |
  |  +-------------------+------+-----------------------------------+  |
  |  | Common Header TLVs                                           |  |
  |  +-------------------+------+-----------------------------------+  |
  |  | VERSION           | 1    | Protocol version                  |  |
  |  | MSG_TYPE          | 1    | INTENT_REQ / CAP_ADV / ERROR      |  |
  |  | MSG_ID            | var  | Unique message identifier         |  |
  |  | SENDER_ID         | var  | Source agent / router ID          |  |
  |  | RECEIVER_ID       | var  | Target agent / router ID          |  |
  |  | TIMESTAMP         | 8    | Unix time / logical time          |  |
  |  | TTL / EXPIRY      | 4    | Validity / hop limit              |  |
  |  | CORRELATION_ID    | var  | Request-response correlation      |  |
  |  | INTEGRITY_TAG     | var  | MAC / signature                   |  |
  |  +-------------------+------+-----------------------------------+  |
  |                                                                    |
  |  +-------------------+------+-----------------------------------+  |
  |  | Payload TLVs (depend on MSG_TYPE)                            |  |
  |  +-------------------+------+-----------------------------------+  |
  |                                                                    |
  |  -- CAPABILITY ADVERTISEMENT (CAP_ADV) --------------------------  |
  |  | AGENT_ID          | var  | Advertising agent identifier      |  |
  |  | ENDPOINT          | var  | Network / logical endpoint        |  |
  |  | FUNC_DESC         | var  | Functional descriptors            |  |
  |  | INTENT_DOMAINS    | var  | Supported intent types            |  |
  |  | IO_SCHEMA         | var  | Input/output constraints          |  |
  |  | PERF_METRICS      | var  | Latency, success rate, etc.       |  |
  |  | RESOURCE_LIMITS   | var  | Token / compute budget            |  |
  |                                                                    |
  |  -- CAPABILITY REFRESH (CAP_REFRESH) ----------------------------  |
  |  | AGENT_ID          | var  | Agent identifier                  |  |
  |  | TTL_UPDATE        | 4    | Extended lifetime                 |  |



Sun & Zhang               Expires 9 August 2026                [Page 10]

Internet-Draft                    IAIP                     February 2026


  |  | METRIC_DELTA      | var  | Updated performance metrics       |  |
  |                                                                    |
  |  -- CAPABILITY DEREGISTER (CAP_DEREGISTER) ----------------------  |
  |  | AGENT_ID          | var  | Agent identifier                  |  |
  |  | REASON_CODE       | 2    | Deregistration reason             |  |
  |  | EFFECTIVE_TIME    | 8    | Time of effect                    |  |
  |                                                                    |
  |  -- INTENT REQUEST (INTENT_REQ) ---------------------------------  |
  |  | OBJECTIVE         | var  | Task objective                    |  |
  |  | CONSTRAINTS       | var  | Preferences / limits              |  |
  |  | CONTEXT           | var  | Context metadata                  |  |
  |  | PRIORITY          | 1    | Request priority                  |  |
  |  | BUDGET            | var  | Cost / token budget               |  |
  |  | PRIVACY_FLAG      | 1    | Intent privacy level              |  |
  |  | OBFUSCATED_INTENT | var  | Encrypted / masked intent         |  |
  |                                                                    |
  |  -- ROUTE DECISION / INTENT RESPONSE ----------------------------  |
  |  | TARGET_AGENT_LIST | var  | Selected target agent(s)          |  |
  |  | MATCH_CONFIDENCE  | var  | Similarity / rank score           |  |
  |  | FORWARDING_INFO   | var  | Next-hop / endpoint               |  |
  |  | FALLBACK_INDIC.   | 1    | Fallback used?                    |  |
  |                                                                    |
  |  -- ROUTING FEEDBACK --------------------------------------------  |
  |  | OUTCOME           | 1    | Success / failure                 |  |
  |  | OBSERVED_LATENCY  | var  | Execution latency                 |  |
  |  | OBSERVED_COST     | var  | Resource usage                    |  |
  |  | ERROR_INFO        | var  | Error details                     |  |
  |                                                                    |
  |  -- ERROR MESSAGE -----------------------------------------------  |
  |  | ERROR_CODE        | 2    | Error identifier                  |  |
  |  | DIAGNOSTIC        | var  | Human-readable info               |  |
  |  | RETRY_AFTER       | 4    | Backoff hint                      |  |
  |                                                                    |
  |  -- SECURITY EXTENSION (SECURITY_EXT) ---------------------------  |
  |  | AUTHN_INFO        | var  | Certificate / token ref           |  |
  |  | AUTHZ_SCOPE       | var  | Authorization scope               |  |
  |  | NONCE             | var  | Anti-replay                       |  |
  |  | SIGNATURE / MAC   | var  | Integrity protection              |  |
  |  | ENCRYPTION_CTX    | var  | Intent confidentiality ctx        |  |
  |                                                                    |
  +--------------------------------------------------------------------+

                      Figure 3: IAIP message format

   The table above summarizes the field requirements.  Key fields
   include:

   *MSG_TYPE*  Identifies the payload type (e.g., 0x01: CAP_ADV, 0x02:



Sun & Zhang               Expires 9 August 2026                [Page 11]

Internet-Draft                    IAIP                     February 2026


      INTENT_REQ).

   *TTL / EXPIRY*  Time-To-Live logic depending on message type.  For
      routing messages (INTENT_REQ), this represents the hop limit.  For
      registration messages, this represents the validity duration in
      seconds.

   *OBJECTIVE (in INTENT_REQ)*  The semantic vector or structured
      description of the task.

   *RESOURCE_LIMITS (in CAP_ADV)*  Specifies operational constraints,
      including token budget per request and computational cost.

   *FALLBACK_INDIC. (in RESPONSE)*  Flag indicating if a generalist
      fallback agent was used (0x01) or a direct match was found (0x00).

8.  Protocol Operation and Core Procedures

   This section specifies the normative processing behavior of the Agent
   Gateway (AG), organized by the functional components defined in
   Section 5.  The Agent Access Component (AAC) handles ingress
   connectivity and security; the Local Capability Registry (LCR)
   manages state; and the Intent Forwarding Routing Table (IFR) executes
   decision logic.

8.1.  Illustrative Protocol Examples

   The examples in this section are provided for illustration only and
   are non-normative.

8.1.1.  Example A: Agent Registration (CAP_ADV)

   A Partner Agent registers its translation service with cost
   constraints.

[Common Header] MSG_TYPE =
          CAP_ADV SENDER_ID = "agent-trans-01", TTL/EXPIRY = 3600 [Payload],
          FUNC_DESC = "service:translation; lang:en-to-zh", RESOURCE_LIMITS =
          "max_tokens=2048", SECURITY_EXT = "(signature bytes...)"

8.1.2.  Example B: Intent Resolution Flow

   *Step 1: Leader Agent sends Intent Request*

[Common Header] MSG_TYPE =
          INTENT_REQ SENDER_ID = "leader-agent-007", MSG_ID = "req-1024"
          [Payload], OBJECTIVE = "(vector: [0.12, 0.95, ...])", BUDGET =
          "100"



Sun & Zhang               Expires 9 August 2026                [Page 12]

Internet-Draft                    IAIP                     February 2026


   *Step 2: Gateway returns Candidate List (Response)*
   The AG finds two matching agents.  The first one is a direct match,
   so Fallback Indicator is 0.

[Common Header] MSG_TYPE =
          RESPONSE RECEIVER_ID = "leader-agent-007", CORRELATION_ID =
          "req-1024" [Payload], TARGET_AGENT_LIST = [1] "agent-trans-01"
          (Conf: 0.92, Endpoint: "10.0.1.5:8080"), [2] "agent-trans-03" (Conf:
          0.85, Endpoint: "10.0.1.8:8080"), FALLBACK_INDIC. = 0x00 (No
          Fallback)

8.1.3.  Example C: Routing Feedback

   After execution, the Leader Agent reports performance metrics back to
   the AG to update the LCR's dynamic scores.

[Common Header] MSG_TYPE =
          ROUTING_FEEDBACK SENDER_ID = "leader-agent-007" [Payload], OUTCOME =
          1 (Success), OBSERVED_LATENCY = 250 (ms), OBSERVED_COST = 50
          (tokens)

8.2.  Agent Access Component (AAC) Operations

   The AAC serves as the termination point for the interconnection
   session.  It MUST intercept all incoming IAIP messages before they
   reach the LCR or IFR.

8.2.1.  Session Authentication and Integrity

   Upon receiving any message, the AAC MUST perform the following
   validations:

   *  *Identity Verification:* Validate the SENDER_ID against the
      credentials provided in the AUTHN_INFO TLV or the underlying
      transport session (e.g., mTLS).
   *  *Message Integrity:* Verify the INTEGRITY_TAG or SIGNATURE.  If
      verification fails, the AAC MUST drop the message and return an
      ERROR with code AUTH_FAILED.

8.2.2.  Ingress Validation

   The AAC acts as the first line of defense.  It MUST validate the
   syntax of Common Header fields (e.g., VERSION, MSG_TYPE).  Malformed
   packets MUST be rejected immediately to protect the internal IFR
   engine.






Sun & Zhang               Expires 9 August 2026                [Page 13]

Internet-Draft                    IAIP                     February 2026


8.3.  Local Capability Registry (LCR) Management

   The LCR maintains the dynamic database of attached Agents.  It
   processes capability management messages validated by the AAC.

8.3.1.  Profile Creation and Updates

   When the AAC forwards a CAP_ADV message, the LCR MUST:

   1.  Extract the AGENT_ID and map it to the provided ENDPOINT.

   2.  Store the FUNC_DESC, INTENT_DOMAINS, and RESOURCE_LIMITS as the
       agent's Capability Profile.

   3.  Set the entry's expiration time to Current_Time + TTL.

8.3.2.  Lifecycle Maintenance

   Upon receiving a CAP_REFRESH, the LCR MUST look up the existing
   profile and extend its validity by TTL_UPDATE.

   The LCR MUST periodically purge entries that have exceeded their
   expiry time without refresh (STALE state) to ensure the IFR does not
   route to dead agents.

8.4.  Intent Forwarding Routing Table (IFR) Decision Logic

   The Intent Forwarding Routing Table (IFR) functions as the dynamic
   routing engine of the Agent Gateway.  After an INTENT_REQ
   successfully passes AAC validation, the IFR MUST evaluate the request
   and produce a ranked TARGET_AGENT_LIST containing one or more
   eligible Partner Agents.

8.4.1.  Candidate Retrieval

   The IFR MUST interpret the OBJECTIVE TLV as an intent descriptor and
   query the Local Capability Registry (LCR) to obtain the current set
   of active Capability Profiles.

8.4.2.  Constraint-Based Filtering

   The IFR MUST apply mandatory constraints to reduce the candidate set
   prior to semantic evaluation.  When a request includes constraint
   fields such as BUDGET, the IFR MUST compare these constraints against
   the corresponding attributes in the Capability Profiles (e.g.,
   RESOURCE_LIMITS) and exclude agents that do not satisfy the required
   conditions.




Sun & Zhang               Expires 9 August 2026                [Page 14]

Internet-Draft                    IAIP                     February 2026


   Additional policy-based constraints MAY be applied according to local
   administrative policy.

8.4.3.  Semantic Evaluation and Ranking

   For the remaining candidates, the IFR MUST perform semantic matching
   between the request intent and the advertised capabilities.  The
   specific matching method is implementation-dependent; however, the
   IFR MUST compute a relative confidence score that reflects the degree
   of intent-capability alignment.

   The IFR MAY incorporate additional operational signals, such as
   historical performance metrics (e.g., latency or success rate), when
   deriving the final ranking.

   The IFR MUST preserve the relative ordering of candidates when
   constructing the TARGET_AGENT_LIST.

8.4.4.  Selection and Fallback

   The IFR SHOULD select the highest-ranked candidates for inclusion in
   the response, subject to local policy.

   If no candidate satisfies the acceptance criteria (e.g., minimum
   confidence threshold), the IFR SHOULD invoke the Fallback Mechanism.
   When fallback is applied, the Agent Gateway MUST set FALLBACK_INDIC
   to 0x01.

8.5.  Forwarding and Loop Prevention

   For multi-hop scenarios, the AG enforces loop prevention using the
   TTL field in the Common Header.  If TTL <= 1, the request is dropped.
   Duplicate MSG_ID, are suppressed to prevent broadcast storms.

8.6.  Reliability and Error Handling

   Errors detected by any component (AAC auth failure, LCR parsing
   error, IFR no-route) MUST result in an ERROR message returned to the
   sender, containing the appropriate ERROR_CODE.

8.7.  Protocol Processing procedure at Agent Gateways

   Figure 3 illustrates the protocol processing pipeline within the
   Agent Gateway (AG).  The protocol operation relies on the
   coordination between three normative functional components: the Agent
   Access Component (AAC), the Local Capability Registry (LCR), and the
   Intent Forwarding Routing Table (IFR).




Sun & Zhang               Expires 9 August 2026                [Page 15]

Internet-Draft                    IAIP                     February 2026


   The process begins when a Partner Agent transmits a capability
   advertisement (CAP_ADV) [Section 8.1.1].

   *Ingress Validation:* The AAC [Section 8.2] intercepts the message to
   perform session authentication and integrity verification.

   *Registry Update:*Upon successful validation, the AAC forwards the
   payload to the LCR [Section 8.3].  The LCR parses the functional
   descriptors and updates its internal database, mapping the agent's
   semantic profile to its network endpoint.

   The routing process is triggered when a Leader Agent submits an
   intent request (INTENT_REQ) [Section 8.1.2].

   *Ingress Validation:*The AAC validates the request format and the
   sender's authorization scope.

   *Routing Decision:*Validated requests are passed to the IFR
   [Section 8.4], which executes the core decision logic:

   *  *Candidate Retrieval:*The IFR queries the LCR [Section 8.4.1] to
      retrieve active agents capable of satisfying the intent objective.

   *  *Filtering:*Mandatory constraints (e.g., budget, latency) are
      applied to prune ineligible candidates [Section 8.4.2].

   *  *Ranking:*The IFR performs semantic evaluation [Section 8.4.3] to
      assign confidence scores to the remaining candidates.

   *  *Selection:*The eligible partner agents are selected based on
      local policy and fallback mechanisms [Section 8.4.4].

   *Egress Processing:*The partner agent list is passed to the
   Forwarding module [Section 8.5].  This module enforces Time-To-Live
   (TTL) checks and duplicate suppression to prevent routing loops
   before dispatching the forwarded request to the Partner Agent.















Sun & Zhang               Expires 9 August 2026                [Page 16]

Internet-Draft                    IAIP                     February 2026


       +--------------+                  +--------------+
       | Leader Agent |                  | Partner Agent|
       | (Source/App) |                  | (Target/Phy) |
       +-------+------+                  +-------+------+
               | (2) Intent Req                  | (1) CAP_ADV
               | [Sec 8.1.2]                     | [Sec 8.1.1]
               v                                 v
   +------------------------------------------------------------------+
   |              Agent Gateway (Interconnection Domain)              |
   |------------------------------------------------------------------|
   |                                                                  |
   | +--------------+        (CAP_ADV)         +--------------------+ |
   | | Agent Access |------------------------->|  Local Capability  | |
   | |  Comp (AAC)  |                          |   Registry (LCR)   | |
   | |  [Sec 8.2]   |                          |     [Sec 8.3]      | |
   | +------+-------+                          +---------+----------+ |
   |        |                                            ^            |
   |        | (INTENT_REQ)                               | Candidate  |
   |        v                                            | Retrieval  |
   | +---------------------------------------------------+----------+ |
   | |      Intent Forwarding Routing Table (IFR) [Sec 8.4]         | |
   | |--------------------------------------------------------------| |
   | | 1. Candidate Retrieval (Query LCR) [Sec 8.4.1] --------------+ |
   | | 2. Constraint Filtering [Sec 8.4.2]                          | |
   | | 3. Semantic Eval & Ranking [Sec 8.4.3]                       | |
   | | 4. Selection & Fallback [Sec 8.4.4]                          | |
   | +------+-------------------------------------------------------+ |
   |        | Selected Target List                                    |
   |        v                                                         |
   | +----------------------+                                         |
   | |  Forwarding & Loop   |                                         |
   | | Prevention [Sec 8.5] |                                         |
   | +------+---------------+                                         |
   |        |                                                         |
   +--------+---------------------------------------------------------+
            | (3) Forwarded Request
            v
     +-------------+
     | Partner Agt |
     | (Execution) |
     +-------------+

         Figure 4: Protocol Processing procedure at Agent Gateways








Sun & Zhang               Expires 9 August 2026                [Page 17]

Internet-Draft                    IAIP                     February 2026


9.  Conclusions

   This document specifies the functional components, protocol
   procedures, and message formats of the Intent-based Agent
   Interconnection Protocol (IAIP).  It defines the mechanisms for
   capability-aware registration, semantic intent resolution, and
   dynamic routing.  By abstracting the complexity of agent discovery
   and intent matching, IAIP ensures scalable and adaptive collaboration
   across heterogeneous agent systems.

10.  Security Considerations

   This document focuses on the Intent-based Agent Interconnection
   Protocol at the Agent Gateway for inter-agent collaboration in the
   Internet of Agents (IoA).  Security of the IoA ecosystem is not
   detailed in this document.  Security considerations relevant to
   cross-domain intent routing, capability advertisement integrity,
   trust federation among multiple agent service providers, and end-to-
   end confidentiality of agent interactions are suggested to be deeply
   discussed through other proposals.

11.  IANA Considerations

   This document makes no request for IANA action.

12.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

Authors' Addresses

   Sheng Sun
   ICT, CAS
   Email: sunsheng@ict.ac.cn


   Xinyi Zhang
   CNIC, CAS
   Email: xyzhang@cnic.cn










Sun & Zhang               Expires 9 August 2026                [Page 18]
