RFC 467 (rfc467) - Page 1 of 7
Proposed change to Host-Host Protocol: Resynchronization of connection status
Alternative Format: Original Text Document
Network Working Group J. Burchfiel
Request for Comments: 467 R. Tomlinson
NIC: 14741 Bolt Beranek and Newman
20 February 1973
Proposed Change To Host-Host Protocol
Resynchronization Of Connection Status
I. Introduction
The current Host-Host protocol (NIC #8246) contains no provisions for
resynchronizing the status information kept at the two ends of each
connection. In particular, if either host suffers a service
interruption, or if a control message is lost or corrupted in an
interface or in the subnet, the status information at the two ends of
the connection will be inconsistent.
Since the current protocol provides no way to correct this condition,
the NCP's at the two ends stay "confused" forever. A frequent and
frustrating symptom of this effect is the "lost allocate" phenomenon,
where the receiving NCP believes that it has bit and message
allocations outstanding, while the sending NCP believes that it does
not have any allocation. As a result, information flow over that
connection can never be restarted.
Use of the Host-Host RST (reset) command is inappropriate here, as it
destroys all connections between the two hosts. What is needed is a
way to reset only the affected connection without disturbing any
others.
A second troublesome symptom of inconsistency in status information
is the "half-closed" connection: after a service interruption or
network partitioning, one NCP may believe that a connection is still
open, while the other believes that the connection is closed. (Does
not exist.) When such an inconsistency is discovered, the "open" end
of the connection should be closed.
Burchfiel