Internet DRAFT - draft-petithuguenin-vipr-proportional-quota
draft-petithuguenin-vipr-proportional-quota
VIPR M. Petit-Huguenin
Internet-Draft Stonyfish
Intended status: Standards Track J. Rosenberg
Expires: April 25, 2012 jdrosen.net
C. Jennings
Cisco
October 23, 2011
Proportional Quota in REsource LOcation And Discovery (RELOAD)
draft-petithuguenin-vipr-proportional-quota-00
Abstract
This document defines an extension to RELOAD [I-D.ietf-p2psip-base]
that limits the number of a specific kind element that can be stored
by one RELOAD peer.
Status of this Memo
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This Internet-Draft will expire on April 25, 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
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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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Quota Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Overlay Configuration Document Extension . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 5
Appendix A. Release notes . . . . . . . . . . . . . . . . . . . . 5
A.1. Modifications between
draft-petithuguenin-vipr-proportional-quota-00 and
draft-petithuguenin-p2psip-proportional-quota-01 . . . . . 6
A.2. Modifications between
draft-petithuguenin-p2psip-proportional-quota-01 and
draft-petithuguenin-p2psip-proportional-quota-00 . . . . . 6
A.3. Modifications between
draft-petithuguenin-p2psip-proportional-quota-00 and
draft-petithuguenin-vipr-reload-usage-00 . . . . . . . . . 6
A.4. Running Code Considerations . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
The base specification of RELOAD defines two variables to set the
storage quota. The first one is the maximum size of an element of a
specific kind, the second one is the maximum number of elements of a
specific kind that can be stored on a specific peer. The combination
of the two variables permits to limit the quantity of data that a
peer have to store.
For kinds that are used with an access control policy that does not
restrict the Resource-IDs, a different algorithm is needed to force
storing nodes to behave. This document describes a quota algorithm
that limits the number of elements of a specific kind that a node can
store in the overlay, independently of the Resource-ID used. Another
way to look at this quota algorithm is that an entity must provide a
number of peers that is proportional to the number of elements of a
specific kind that this entity wants to store.
It is important to understand that this quota works only for an
overlay comprising only peers, and so with a configuration file
containing a <clients-permitted> element set to false.
2. Terminology
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 [RFC2119].
3. Quota Algorithm
A peer responsible for storing kinds using the quota algorithm
described in this document MUST maintain a count of the number of
unique entries being stored per signer for each kind. This operation
does not require to add a field containing the Node-ID as the Node-ID
of the signer is always available indirectly from the signature field
of each element stored.
For example if a peer is storing 5 Resource-IDs and at each of those
5 there are two entries, all signed by the same Node-ID, it means
this node is currently storing 10 unique entries for that Node-ID.
When performing the quota checks for an entry, the peer starts by
verifying that the size of the entry is consistent. If the entry if
not for a replica, it then takes the <max-count> configuration
parameter for this overlay, which measures the amount of entries of a
specific kind a particular node can store when a <max-count-
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per>SIGNER</max-count-per> configuration parameter is also present.
That value is divided by the fraction of the overlay owned by this
peer. If the result is less than one, it is rounded up to two. This
is the maximum number of unique entries that can be stored for this
signer. If the peer is not yet storing this many entries for that
Node-ID, the store is allowed.
Note that when evaluating a Store Request containing multiple entries
per kind, the count of unique entries used for the evaluation is
incremented after each successful check, but the count will be reset
to its initial value if one of the check fails.
The algorithm does not apply to the replicas created by the topology
plugin. If another level of replication is done at the application
level, the <max-count> value must be adjusted accordingly.
Note that because of imperfect distribution of Resource-IDs across
the ring, new entries can be rejected even if the total count is
under the limit. It is the responsibility of the storing entity to
calculate the maximum acceptable probability of rejection and to
increase the number of peers accordingly.
[[Note: Add here the equation that can be used to calculate the
probability of rejection, so applications using this quota mechanism
can recommend a multiplier coefficient]]
4. Overlay Configuration Document Extension
This document extends the overlay configuration document by defining
a new element in the "urn:ietf:params:xml:ns:p2p:quota" namespace.
The <max-count-per> element changes the meaning of the <max-count>
variable. The value "PEER" forces the <max-count> to be interpreted
as been per storing peer, which is the default quota algorithm when
this extension is not used. The value "SIGNER" forces the <max-
count> to be interpreted as been per signer, which is the algorithm
defined by this document.
The Compact Relax NG Grammar for this element is:
namespace pqt = "urn:ietf:params:xml:ns:p2p:quota"
kind-parameter &= element pqt:max-count-per { max-count-per-type }
max-count-per-type |= "PEER"
max-count-per-type |= "SIGNER"
max-count-per-type |= xsd:string # extensions
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5. Security Considerations
TBD
6. IANA Considerations
This document adds the following URN to the "XML Namespaces" class of
the "IETF XML Registry":
urn:ietf:params:xml:ns:p2p:quota
7. Acknowledgements
Thanks to Hakim Mehmood and Mark Hendrickson for their explanations
on the implementation of the quota algorithm.
This document was written with the xml2rfc tool described in
[RFC2629].
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.ietf-p2psip-base]
Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., and
H. Schulzrinne, "REsource LOcation And Discovery (RELOAD)
Base Protocol", draft-ietf-p2psip-base-18 (work in
progress), August 2011.
8.2. Informative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
Appendix A. Release notes
This section must be removed before publication as an RFC.
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A.1. Modifications between
draft-petithuguenin-vipr-proportional-quota-00 and
draft-petithuguenin-p2psip-proportional-quota-01
o The quota does not apply to replicas.
o Draft moved to VIPR WG.
o Nits.
A.2. Modifications between
draft-petithuguenin-p2psip-proportional-quota-01 and
draft-petithuguenin-p2psip-proportional-quota-00
o Changed "storing peer" to "signer" as this works also for replica
peers.
o The default quota algorithm is per storing peer, not per
Resource-ID.
o Changed the constants in the XML extension accordingly.
o Added running code considerations for reference implementation.
A.3. Modifications between
draft-petithuguenin-p2psip-proportional-quota-00 and
draft-petithuguenin-vipr-reload-usage-00
o Instead of having a StorageQuota parameter that gives the maximum
number of entries, reused the max-count parameter (that is
mandatory anyway) and changes its meaning.
o Removed the 3x multiplier to account for the application layer
COPY, as it is application specific.
o Removed the additional 3x multiplier to compensate for imperfect
distribution, and moved the responsibility to the storing nodes.
A.4. Running Code Considerations
o Reference Implementation
(<http://debian.implementers.org/testing/source/reload.tar.gz>).
Marc Petit-Huguenin. Implements version vipr-00.
Authors' Addresses
Marc Petit-Huguenin
Stonyfish
Email: marc@stonyfish.com
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Jonathan Rosenberg
jdrosen.net
Monmouth, NJ
US
Email: jdrosen@jdrosen.net
URI: http://www.jdrosen.net
Cullen Jennings
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Phone: +1 408 421-9990
Email: fluffy@cisco.com
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