# Secure Low-Latency Interactive Messaging SLIM

[6 · Coordinate](/category/coordinate/)

| Secure Low-Latency Interactive Messaging |
| --- |
| Category | [Coordinate](/category/coordinate/) |
| Governed by | Linux Foundation (AGNTCY project); originally donated by Cisco |
| Status | "Next-generation communication framework that provides the secure, scalable transport layer for AI agent protocols like A2A and MCP" |
| Phase | working group |
| Implementation | shipping |
| Adoption | unmeasured |
| Version | IETF individual draft draft-mpsb-agntcy-slim-00; active GitHub development |
| Specification | [https://github.com/agntcy/slim](https://github.com/agntcy/slim) |
| Found at | none |
| Last checked | 2026-09-06 |

[Coordinate](/category/coordinate/) SLIM (Secure Low-Latency Interactive Messaging) is a messaging/transport framework built for the AGNTCY project, intended to serve as the secure, scalable transport layer underneath higher-level agent protocols such as A2A and MCP [[1]](#ref-1). It solves a gap those protocols leave open: neither A2A nor MCP specifies a low-latency, group-aware, end-to-end-encrypted messaging transport; SLIM supports request-response, publish-subscribe, fire-and-forget, and streaming interaction patterns, and builds in authentication, authorization, and end-to-end (MLS) encryption at the transport layer [[2]](#ref-2). Architecturally it splits into a Data Plane (pure hierarchical-name-based packet routing, content-blind), a Session Layer (reliable delivery, end-to-end MLS encryption, group membership), and a Control Plane (configuration, monitoring, orchestration) — letting lightweight routing nodes run only the data plane while applications carry the full stack via language bindings (Python, Go, .NET, Java, Kotlin) [[1]](#ref-1).

## Overview
SLIM does not define agent discovery, identity, or task semantics itself — those are the roles of A2A/MCP and AGNTCY's separate directory/identity components; SLIM's own README frames itself purely as the transport underneath those protocols [[1]](#ref-1).

Current state: the agntcy/slim repository was created 2025-02-05, is Apache-2.0 licensed, and is actively maintained (CI, code coverage, and OpenSSF Scorecard badges all present and green as of this check) [[1]](#ref-1). AGNTCY itself — the umbrella project SLIM belongs to — was donated by Cisco to the Linux Foundation, with Dell Technologies, Google Cloud, Oracle, and Red Hat joining as formative members, to standardize open multi-agent-system infrastructure including discovery, identity, messaging (SLIM), and observability [[2]](#ref-2). A SLIM specification has also been filed as an individual IETF Internet-Draft, draft-mpsb-agntcy-slim-00, though it is not yet a working-group document — this record treats the Linux Foundation/AGNTCY project as SLIM's primary governance home given that the code, documentation, and formative-member structure all live there, and marks track as linux-foundation rather than ietf accordingly. Implementations exist and ship as bindings across five languages plus integrations for A2A and MCP transport (slim-a2a-python, slim-mcp-python) and OpenTelemetry [[1]](#ref-1). What is unresolved: no independently measured adoption count was found; this is a genuinely new record added during this verification pass per the coordinator's occupant-diff instruction, and its exact relationship to the IETF draft (same authors? formally submitted by the AGNTCY project?) was not further disambiguated in this pass.

## Discovery and probe

none · none

```
none none — SLIM is a session/routing protocol operated by a data-plane node over its own wire format, not a document served at a fixed well-known HTTP path; no origin-fetchable probe was identified
parse:     not applicable: there is no HTTP response to parse; presence would instead be inferred from a target's published SLIM node configuration or its listed use of the slim-a2a-python / slim-mcp-python bindings
on absent: not applicable — SLIM has no well-known discovery surface as of this verification; see summary_md
```

Not probed live: not-http. SLIM is a transport operated by data-plane nodes on its own wire protocol.

## History
- 2026-09-06 — new record created during coordinate-step verification; verified against github.com/agntcy/slim README, Linux Foundation/AGNTCY donation coverage, and the IETF individual draft draft-mpsb-agntcy-slim-00

## Instances

- [agntcy/slim (Rust core, data plane / session layer / control plane)](https://github.com/agntcy/slim) · Observed 2026-09-05 · service
- [AGNTCY formative members: Cisco, Dell Technologies, Google Cloud, Oracle, Red Hat](https://www.techzine.eu/blogs/infrastructure/133408/cisco-donates-agntcy-to-linux-foundation-internet-of-agents-on-its-way/) · Observed 2026-09-05 · business
- [Swisscom](https://www.linkedin.com/posts/vijoy_happy-1st-birthday-agntcy-a-year-ago-this-activity-7488620714682408962-LJBs) · Observed 2026-07-30 · business

Every instance with its source is listed on the [instances page](/instances/).

## See also

## References

- SLIM (Secure Low-Latency Interactive Messaging) is described by its own README as a next-generation communication framework providing the secure, scalable transport layer for AI agent protocols like A2A and MCP, with a Data Plane, Session Layer, and Control Plane architecture; the repository is Apache-2.0 licensed and was created 2025-02-05 under the agntcy GitHub org. — [https://raw.githubusercontent.com/agntcy/slim/main/README.md](https://raw.githubusercontent.com/agntcy/slim/main/README.md) (2026-09-05) VERIFIED
- Cisco donated the AGNTCY project, which SLIM belongs to, to the Linux Foundation; formative members named include Cisco, Dell Technologies, Google Cloud, Oracle, and Red Hat, and the project covers discovery, identity, messaging, and observability for multi-vendor AI agents, with SLIM as its messaging-transport protocol. — [https://www.techzine.eu/blogs/infrastructure/133408/cisco-donates-agntcy-to-linux-foundation-internet-of-agents-on-its-way/](https://www.techzine.eu/blogs/infrastructure/133408/cisco-donates-agntcy-to-linux-foundation-internet-of-agents-on-its-way/) (2026-09-05) VERIFIED
- A SLIM specification has also been filed at the IETF as an individual draft, draft-mpsb-agntcy-slim-00, "Secure Low-Latency Interactive Messaging (SLIM)." — [https://www.ietf.org/archive/id/draft-mpsb-agntcy-slim-00.html](https://www.ietf.org/archive/id/draft-mpsb-agntcy-slim-00.html) (2026-09-05) REPORTED

[JSON](/data/protocols/slim.json) · [Markdown](/protocols/slim/index.md)