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Interim Revision to Appendix F of BBN 1822 (RFC0716)

IP.com Disclosure Number: IPCOM000003761D
Original Publication Date: 1976-May-24
Included in the Prior Art Database: 2000-Sep-13
Document File: 2 page(s) / 3K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

D.C. Walden: AUTHOR [+2]

Abstract

Over the past few months we have become aware that there has been some confusion as to how to operate a Host connected to an IMP as a Very Distant Host (or VDH). Therefore, next time BBN Report 1822 ("Specifications for the Interconnection of a Host and an IMP") is revised, we will include additional information on how the IMP side of a VDH connection works and how the Host side may operate most efficiently. As an interim measure, we are distributing this RFC which takes the form of a (logical) update to Appendix F of BBN Report 1822.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 82% of the total text.

Network Working Group David Walden

Request for Comments: 716 Joel Levin

NIC #35534 May 24, 1976

Interim Revision to Appendix F of BBN Report 1822

Over the past few months we have become aware that there has been

some confusion as to how to operate a Host connected to an IMP as a

Very Distant Host (or VDH). Therefore, next time BBN Report 1822

("Specifications for the Interconnection of a Host and an IMP") is

revised, we will include additional information on how the IMP side

of a VDH connection works and how the Host side may operate most

efficiently. As an interim measure, we are distributing this RFC

which takes the form of a (logical) update to Appendix F of BBN

Report 1822.

On page F-6 on Appendix F, delete the second footnote.

On page F-7, find the phrase "... and the odd/even bit is complemented."

on line 17 of the page. Delete the rest of the page and insert the

following text:

In a standard Host to IMP interface, messages are delivered in a

specific order and received in the same order. A Very Distant Host

interface operates similarly in that messages are passed, for

example, from the IMP to its RTP in order; the Host's RTP then

delivers them to its receiving process in the same order. It is

important to note, however, that between these two software

interfaces there is nothing said about ordering. In particular, if

the special interface detects an error in a packet, for example,

the receiving RTP will discard the packet. The next packet may

arrive on another logical channel before the sending RTP

retransmits the discarded and unacknowledged packet, and the

receiver should be prepared to accept this packet out of order.

The protocol described above explicitly permits such out-of-order

behavior between the RTPs, requiring only that the transmit portion

of the RTP fill its channels in sequence (one to channel zero, one

to channel one, one to channel zero, etc.), and that the receive

portion of the RTP empty its channels in sequence. In addition, to

insure correct sequencing, the first channel filled or emptied

after initialization must be channel zero. Null packets use

neither a channel nor a channel number when sent and are not

acknowledged when received.

When packets must be retransmitted until acknowledged, processing

and transmission delay may cause acknowledgement to be delayed for

more than one transmission time. Unnecessary retransmission may

interfere with new transmissions, as well as placing an added

-1-

burden on both receiver and transmitter. Ther...