One document matched: draft-barnes-atoca-delivery-00.txt
ATOCA R. Barnes
Internet-Draft BBN Technologies
Intended status: Informational October 24, 2011
Expires: April 26, 2012
Scalable Robust Alerting Protocol (SCRAP)
draft-barnes-atoca-delivery-00.txt
Abstract
Emergency alerts need to be delivered reliably from one source to
many recipients at once. TCP is unsuitable for this style of
delivery, because the large number of acknowledgements would likely
cause network congestion. This document defines a UDP-based protocol
for delivering alerts that supports fragmentation and retransmission
for reliability, and allows the sender of a datagram to control
whether acknowledgements are sent.
Please send feedback to the atoca@ietf.org mailing list.
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
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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 April 26, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Open Questions . . . . . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Packet Format . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. URI Format . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5. Sender Processing . . . . . . . . . . . . . . . . . . . . . . . 3
6. Receiver Processing . . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
[TODO]
1.1. Open Questions
Should we include hash value in URI format? Or leave that to the
metadata/configuration protocol?
Should we randomize the order in which fragments are transmitted in
order to deal with correlated loss?
2. Definitions
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 RFC 2119 [RFC2119].
3. Packet Format
[Sent over UDP. Default port is XXX.]
[Payload format: Alert ID (2 octets / 16 bits); Fragment number (1
octet / 8 bits); Number of fragments in alert (1 octet / 8 bits);
Alert data (remaining octets)]
[Content of reassembled packets MUST be an ESCAPE-formatted alert]
4. URI Format
[Specifies the format/source of an alert that will be sent]
[alert-src:[host/IP]:[srcport]?:[dstport]]
5. Sender Processing
[Choose an alert ID]
[Divide payload into fragments that will fit within an MTU]
[Attach headers to fragments]
[Transmit fragments in order]
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[Re-transmit the sequence to deal with loss:]
[Probability of receipt given loss (p=P(success)), #fragments (F),
#retransmissions (R), : q = (1 - (1-p)^R)^F]
[Number of retransmissions given loss (1-p), resilience (q),
#fragments (F): R = log(1-q^(1/F)) / log(1-p)]
6. Receiver Processing
[Maintain a set of alert buffers identified by alert ID (possibly an
empty set)]
[Alert buffer contents: alert id; fragments to be received; list of
fragment numbers; list of fragments]
[When an alert packet arrives...]
[If there is a buffer for its ID, add it to the buffer; if the buffer
is complete, re-assemble, validate ESCAPE, and deliver alert to
higher layer]
[If there is not a buffer for its ID, then allocate a new one and add
the fragment.]
[If all fragments for an alert do not arrive within T1 milliseconds,
discard the buffer; default T1=5000]
7. IANA Considerations
[Default port number]
8. Security Considerations
[This protocol provides no security protections; security provided by
ESCAPE.]
[Main concern is DOS, mitigated by buffer timeouts; at worst, have to
buffer 2^32 octets, if all buffers full for all alert IDs. MAY
impose limits on buffer size / number of buffers active
simultaneously. ]
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9. Acknowledgements
[TODO]
10. References
10.1. Normative References
[CAP] Botterell, A. and E. Jones, "Common Alerting Protocol
v1.1", October 2005.
[RFC1421] Linn, J., "Privacy Enhancement for Internet Electronic
Mail: Part I: Message Encryption and Authentication
Procedures", RFC 1421, February 1993.
[RFC1952] Deutsch, P., Gailly, J-L., Adler, M., Deutsch, L., and G.
Randers-Pehrson, "GZIP file format specification version
4.3", RFC 1952, May 1996.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[RFC3370] Housley, R., "Cryptographic Message Syntax (CMS)
Algorithms", RFC 3370, August 2002.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70,
RFC 5652, September 2009.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.
[RFC5754] Turner, S., "Using SHA2 Algorithms with Cryptographic
Message Syntax", RFC 5754, January 2010.
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10.2. Informative References
[I-D.ietf-atoca-requirements]
Schulzrinne, H., Norreys, S., Rosen, B., and H.
Tschofenig, "Requirements, Terminology and Framework for
Exigent Communications", draft-ietf-atoca-requirements-01
(work in progress), January 2011.
Author's Address
Richard Barnes
BBN Technologies
9861 Broken Land Parkway
Columbia, MD 21046
US
Phone: +1 410 290 6169
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