RFC 721 · HISTORIC · 1976
MON · 27 JUL 2026
Out-of-Band Control Signals in a Host-to-Host Protocol
Overview
RFC 721, “Out-of-Band Control Signals in a Host-to-Host Protocol”, is a Historic document published in September 1976 by L.L. Garlick. It has been obsoleted by RFC 7805 — refer to the newer document for the authoritative version. The canonical text is published by the RFC Editor.
What “Historic” means
A specification that has been superseded or is otherwise no longer recommended for use.
Read this RFC
The canonical text of RFC 721 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 1976
- RFC 720 Address Specification Syntax for Network Mail
- RFC 722 Thoughts on Interactions in Distributed Services
- RFC 719 Discussion on RCTE
- RFC 718 Comments on RCTE from the Tenex Implementation Experience
- RFC 717 Assigned Network Numbers
- RFC 716 Interim Revision to Appendix F of BBN 1822
- RFC 714 Host-Host Protocol for an ARPANET-Type Network
- RFC 713 MSDTP-Message Services Data Transmission Protocol