draft-ietf-rserpool-policies-00.txt   draft-ietf-rserpool-policies-01.txt 
Network Working Group M. Tuexen Network Working Group M. Tuexen
Internet-Draft Muenster Univ. of Applied Sciences Internet-Draft Muenster Univ. of Applied Sciences
Expires: April 16, 2005 T. Dreibholz Expires: December 14, 2005 T. Dreibholz
University of Duisburg-Essen University of Duisburg-Essen
October 16, 2004 June 12, 2005
Reliable Server Pooling Policies Reliable Server Pooling Policies
draft-ietf-rserpool-policies-00.txt draft-ietf-rserpool-policies-01.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes server pool policies for Reliable Server This document describes server pool policies for Reliable Server
Pooling including considerations for implementing them at name Pooling including considerations for implementing them at name
servers and pool users. servers and pool users.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology and Definitions . . . . . . . . . . . . . . . . . 4 2. Terminology and Definitions . . . . . . . . . . . . . . . . . 4
2.1 Load . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1 Load . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Weight . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Weight . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Static Policies . . . . . . . . . . . . . . . . . . . . . . . 5 3. Non-Adaptive Policies . . . . . . . . . . . . . . . . . . . . 5
3.1 Round Robin Policy . . . . . . . . . . . . . . . . . . . . 5 3.1 Round Robin Policy . . . . . . . . . . . . . . . . . . . . 5
3.1.1 Description . . . . . . . . . . . . . . . . . . . . . 5 3.1.1 Description . . . . . . . . . . . . . . . . . . . . . 5
3.1.2 Name Server Considerations . . . . . . . . . . . . . . 5 3.1.2 Name Server Considerations . . . . . . . . . . . . . . 5
3.1.3 Pool User Considerations . . . . . . . . . . . . . . . 5 3.1.3 Pool User Considerations . . . . . . . . . . . . . . . 5
3.1.4 Pool Member Selection Policy Parameter . . . . . . . . 5 3.1.4 Pool Member Selection Policy Parameter . . . . . . . . 5
3.2 Weighted Round Robin Policy . . . . . . . . . . . . . . . 5 3.2 Weighted Round Robin Policy . . . . . . . . . . . . . . . 5
3.2.1 Description . . . . . . . . . . . . . . . . . . . . . 5 3.2.1 Description . . . . . . . . . . . . . . . . . . . . . 5
3.2.2 Name Server Considerations . . . . . . . . . . . . . . 6 3.2.2 Name Server Considerations . . . . . . . . . . . . . . 6
3.2.3 Pool User Considerations . . . . . . . . . . . . . . . 6 3.2.3 Pool User Considerations . . . . . . . . . . . . . . . 6
3.2.4 Pool Member Selection Policy Parameter . . . . . . . . 6 3.2.4 Pool Member Selection Policy Parameter . . . . . . . . 6
3.3 Random Policy . . . . . . . . . . . . . . . . . . . . . . 6 3.3 Random Policy . . . . . . . . . . . . . . . . . . . . . . 6
3.3.1 Description . . . . . . . . . . . . . . . . . . . . . 6 3.3.1 Description . . . . . . . . . . . . . . . . . . . . . 6
3.3.2 Name Server Considerations . . . . . . . . . . . . . . 6 3.3.2 Name Server Considerations . . . . . . . . . . . . . . 6
3.3.3 Pool User Considerations . . . . . . . . . . . . . . . 6 3.3.3 Pool User Considerations . . . . . . . . . . . . . . . 6
3.3.4 Pool Member Selection Policy Parameter . . . . . . . . 7 3.3.4 Pool Member Selection Policy Parameter . . . . . . . . 7
3.4 Weighted Random Policy . . . . . . . . . . . . . . . . . . 7 3.4 Weighted Random Policy . . . . . . . . . . . . . . . . . . 7
3.4.1 Description . . . . . . . . . . . . . . . . . . . . . 7 3.4.1 Description . . . . . . . . . . . . . . . . . . . . . 7
3.4.2 Name Server Considerations . . . . . . . . . . . . . . 7 3.4.2 Name Server Considerations . . . . . . . . . . . . . . 7
3.4.3 Pool User Considerations . . . . . . . . . . . . . . . 7 3.4.3 Pool User Considerations . . . . . . . . . . . . . . . 7
3.4.4 Pool Member Selection Policy Parameter . . . . . . . . 7 3.4.4 Pool Member Selection Policy Parameter . . . . . . . . 7
4. Dynamic Policies . . . . . . . . . . . . . . . . . . . . . . . 8 4. Adaptive Policies . . . . . . . . . . . . . . . . . . . . . . 8
4.1 Least Used Policy . . . . . . . . . . . . . . . . . . . . 8 4.1 Least Used Policy . . . . . . . . . . . . . . . . . . . . 8
4.1.1 Description . . . . . . . . . . . . . . . . . . . . . 8 4.1.1 Description . . . . . . . . . . . . . . . . . . . . . 8
4.1.2 Name Server Considerations . . . . . . . . . . . . . . 8 4.1.2 Name Server Considerations . . . . . . . . . . . . . . 8
4.1.3 Pool User Considerations . . . . . . . . . . . . . . . 8 4.1.3 Pool User Considerations . . . . . . . . . . . . . . . 8
4.1.4 Pool Member Selection Policy Parameter . . . . . . . . 8 4.1.4 Pool Member Selection Policy Parameter . . . . . . . . 8
4.2 Least Used with Degradation Policy . . . . . . . . . . . . 8 4.2 Least Used with Degradation Policy . . . . . . . . . . . . 8
4.2.1 Description . . . . . . . . . . . . . . . . . . . . . 8 4.2.1 Description . . . . . . . . . . . . . . . . . . . . . 8
4.2.2 Name Server Considerations . . . . . . . . . . . . . . 9 4.2.2 Name Server Considerations . . . . . . . . . . . . . . 9
4.2.3 Pool User Considerations . . . . . . . . . . . . . . . 9 4.2.3 Pool User Considerations . . . . . . . . . . . . . . . 9
4.2.4 Pool Member Selection Policy Parameter . . . . . . . . 9 4.2.4 Pool Member Selection Policy Parameter . . . . . . . . 9
4.3 Priority Least Used Policy . . . . . . . . . . . . . . . . 9 4.3 Priority Least Used Policy . . . . . . . . . . . . . . . . 9
4.3.1 Description . . . . . . . . . . . . . . . . . . . . . 9 4.3.1 Description . . . . . . . . . . . . . . . . . . . . . 9
4.3.2 Name Server Considerations . . . . . . . . . . . . . . 10 4.3.2 Name Server Considerations . . . . . . . . . . . . . . 10
4.3.3 Pool User Considerations . . . . . . . . . . . . . . . 10 4.3.3 Pool User Considerations . . . . . . . . . . . . . . . 10
4.3.4 Pool Member Selection Policy Parameter . . . . . . . . 10 4.3.4 Pool Member Selection Policy Parameter . . . . . . . . 10
4.4 Randomized Least Used Policy . . . . . . . . . . . . . . . 10 4.4 Randomized Least Used Policy . . . . . . . . . . . . . . . 10
4.4.1 Description . . . . . . . . . . . . . . . . . . . . . 10 4.4.1 Description . . . . . . . . . . . . . . . . . . . . . 10
4.4.2 Name Server Considerations . . . . . . . . . . . . . . 10 4.4.2 Name Server Considerations . . . . . . . . . . . . . . 11
4.4.3 Pool User Considerations . . . . . . . . . . . . . . . 11 4.4.3 Pool User Considerations . . . . . . . . . . . . . . . 11
4.4.4 Pool Member Selection Policy Parameter . . . . . . . . 11 4.4.4 Pool Member Selection Policy Parameter . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1 Normative References . . . . . . . . . . . . . . . . . . . . 11 7.1 Normative References . . . . . . . . . . . . . . . . . . . 12
7.2 Informative References . . . . . . . . . . . . . . . . . . . 12 7.2 Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 14
1. Introduction 1. Introduction
The protocols defined in ENRP [5], ASAP [4] and Parameters [3] The protocols defined in ENRP [5], ASAP [4] and Parameters [3]
support a variety of server policies. Some of the policies use support a variety of server policies. Some of the policies use
dynamic load information of the pool elements and others do not. dynamic load information of the pool elements and others do not.
Therefore, we classify them as dynamic and static. The selection of Therefore, we classify them as adaptive and non-adaptive. The
the pool user is performed by two different entities. Some of the selection of the pool user is performed by two different entities.
consequences for policies which are not stateless are described in Some of the consequences for policies which are not stateless are
Performance [7]. described in Performance [7].
Therefore this document describes not only packet formats but also Therefore this document describes not only packet formats but also
gives a detailed description of the procedures to be followed at the gives a detailed description of the procedures to be followed at the
name servers and the pool users to implement each server policy. name servers and the pool users to implement each server policy.
2. Terminology and Definitions 2. Terminology and Definitions
2.1 Load 2.1 Load
The term load is a value specifying how much a pool element's The term load is a value specifying how much a pool element's
resources are currently utilized. 0x000000 states, that the pool resources are currently utilized. 0x000000 states, that the pool
element is not utilized (0%), 0xffffff states that it is fully element is not utilized (0%), 0xffffff states that it is fully
utilized (100%). Defining what utilization means is utilized (100%). Defining what utilization means is application-
application-dependent and out of the scope of RSerPool. However, it dependent and out of the scope of RSerPool. However, it is required
is required that all pool elements of the same pool using load that all pool elements of the same pool using load information have
information have the same definition of load. the same definition of load.
For example, load may define the current amount of users out of a For example, load may define the current amount of users out of a
maximum on a FTP server, the CPU usage of a database server or the maximum on a FTP server, the CPU usage of a database server or the
memory utilization of a compute service. memory utilization of a compute service.
2.2 Weight 2.2 Weight
Weight defines a pool element's service capacity relatively to other Weight defines a pool element's service capacity relatively to other
pool elements of the same pool. Theoretically, there is no upper pool elements of the same pool. Theoretically, there is no upper
limit for weight values (although limited by datatype size). limit for weight values (although limited by datatype size).
skipping to change at page 5, line 5 skipping to change at page 5, line 5
A weight of 0 denotes that the pool element is not capable of A weight of 0 denotes that the pool element is not capable of
providing any service, a weight of 2*n denotes that the pool element providing any service, a weight of 2*n denotes that the pool element
is capable of providing a two times better service than a pool is capable of providing a two times better service than a pool
element having weight n. element having weight n.
For example, weight may define a compute service's computation For example, weight may define a compute service's computation
capacity. That is, a pool element of weight 100 will complete a work capacity. That is, a pool element of weight 100 will complete a work
package in half of the time compared to a pool element of weight 50. package in half of the time compared to a pool element of weight 50.
3. Static Policies 3. Non-Adaptive Policies
3.1 Round Robin Policy 3.1 Round Robin Policy
3.1.1 Description 3.1.1 Description
The Round Robin (RR) policy is a very simple and efficient policy The Round Robin (RR) policy is a very simple and efficient policy
which requires state. This policy is denoted as the default policy which requires state. This policy is denoted as the default policy
and MUST be supported by all RSerPool components. and MUST be supported by all RSerPool components.
3.1.2 Name Server Considerations 3.1.2 Name Server Considerations
skipping to change at page 7, line 48 skipping to change at page 8, line 4
3.4.4 Pool Member Selection Policy Parameter 3.4.4 Pool Member Selection Policy Parameter
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Param Type = 0x6 | Length = 0x8 | | Param Type = 0x6 | Length = 0x8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x4 | Weight | | Policy=0x4 | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
o Weight: Weight constant for the WRAND process. o Weight: Weight constant for the WRAND process.
4. Dynamic Policies 4. Adaptive Policies
4.1 Least Used Policy 4.1 Least Used Policy
4.1.1 Description 4.1.1 Description
The Least Used (LU) policy uses load information provided by the pool The Least Used (LU) policy uses load information provided by the pool
elements to select the lowest-loaded pool elements within the pool. elements to select the lowest-loaded pool elements within the pool.
4.1.2 Name Server Considerations 4.1.2 Name Server Considerations
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will be fully loaded. PLU allows to specify this load degradation in will be fully loaded. PLU allows to specify this load degradation in
the policy information, the selection is made on the lowest sum of the policy information, the selection is made on the lowest sum of
load and degradation value. That is, A will be selected (50+10=60) load and degradation value. That is, A will be selected (50+10=60)
instead of B (50+50=100). instead of B (50+50=100).
4.3.2 Name Server Considerations 4.3.2 Name Server Considerations
The name server SHOULD select at most the requested number of pool The name server SHOULD select at most the requested number of pool
elements. Their sums of load + degradation SHOULD be the lowest elements. Their sums of load + degradation SHOULD be the lowest
possible ones within the pool. Each element MUST NOT be reported possible ones within the pool. Each element MUST NOT be reported
more than once to the pool user. If there is a choice of more than once to the pool user. If there is a choice of equal-
equal-valued pool element entries, round robin SHOULD be made between valued pool element entries, round robin SHOULD be made between these
these elements. The returned list of pool elements MUST be sorted elements. The returned list of pool elements MUST be sorted
ascending by the sum of load and degradation value. ascending by the sum of load and degradation value.
4.3.3 Pool User Considerations 4.3.3 Pool User Considerations
The pool user should try to use the pool elements returned from the The pool user should try to use the pool elements returned from the
list in the order returned by the name server. A subsequent call for list in the order returned by the name server. A subsequent call for
name resolution may result in the same list. Therefore, it is name resolution may result in the same list. Therefore, it is
RECOMMENDED for a pool user to request multiple entries in order to RECOMMENDED for a pool user to request multiple entries in order to
have a sufficient amount of feasible backup entries available. have a sufficient amount of feasible backup entries available.
skipping to change at page 12, line 6 skipping to change at page 12, line 11
others (reserved by IETF) others (reserved by IETF)
7. References 7. References
7.1 Normative References 7.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Bradner, S., "Intellectual Property Rights in IETF Technology", [2] Bradner, S., "Intellectual Property Rights in IETF Technology",
BCP 79, RFC 3668, February 2004. RFC 3668, February 2004.
[3] Stewart, R., Xie, Q. and M. Tuexen, "Aggregate Server Access [3] Stewart, R., Xie, Q., and M. Tuexen, "Aggregate Server Access
Protocol (ASAP) and Endpoint Name Resolution (ENRP) Protocol (ASAP) and Endpoint Name Resolution (ENRP)
Parameters", draft-ietf-rserpool-common-param-07 (work in Parameters", draft-ietf-rserpool-common-param-08 (work in
progress), October 2004. progress), February 2005.
[4] Stewart, R., Xie, Q., Stillman, M. and M. Tuexen, "Aggregate [4] Stewart, R., Xie, Q., Stillman, M., and M. Tuexen, "Aggregate
Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-10 Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-11
(work in progress), October 2004. (work in progress), February 2005.
[5] Xie, Q., Stewart, R. and M. Stillman, "Enpoint Name Resolution [5] Xie, Q., Stewart, R., and M. Stillman, "Enpoint Name Resolution
Protocol (ENRP)", draft-ietf-rserpool-enrp-10 (work in Protocol (ENRP)", draft-ietf-rserpool-enrp-11 (work in
progress), October 2004. progress), February 2005.
[6] Stillman, M., "Threats Introduced by Rserpool and Requirements [6] Stillman, M., "Threats Introduced by Rserpool and Requirements
for Security in response to Threats", for Security in response to Threats",
draft-ietf-rserpool-threats-03 (work in progress), July 2004. draft-ietf-rserpool-threats-04 (work in progress), January 2005.
7.2 Informative References 7.2 Informative References
[7] Dreibholz, T., Rathgeb, E. and M. Tuexen, "Load Distribution [7] Dreibholz, T., Rathgeb, E., and M. Tuexen, "Load Distribution
Performance of the Reliable Server Pooling Framework", Submitted Performance of the Reliable Server Pooling Framework", Submitted
to Globecom 2004. to Globecom 2004.
Authors' Addresses Authors' Addresses
Michael Tuexen Michael Tuexen
Muenster University of Applied Sciences Muenster University of Applied Sciences
Stegerwaldstrasse 39 Stegerwaldstrasse 39
48565 Steinfurt 48565 Steinfurt
Germany Germany
EMail: tuexen@fh-muenster.de Email: tuexen@fh-muenster.de
Thomas Dreibholz Thomas Dreibholz
University of Duisburg-Essen, Institute for Experimental Mathematics University of Duisburg-Essen, Institute for Experimental Mathematics
Ellernstrasse 29 Ellernstrasse 29
45326 Essen, Nordrhein-Westfalen 45326 Essen, Nordrhein-Westfalen
Germany Germany
Phone: +49 201 183-7637 Phone: +49 201 183-7637
Fax: +49 201 183-7673 Fax: +49 201 183-7673
EMail: dreibh@exp-math.uni-essen.de Email: dreibh@exp-math.uni-essen.de
URI: http://www.exp-math.uni-essen.de/~dreibh/ URI: http://www.exp-math.uni-essen.de/~dreibh/
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
skipping to change at page 13, line 41 skipping to change at page 14, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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