draft-ietf-rserpool-policies-03.txt   draft-ietf-rserpool-policies-04.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
Intended status: Informational T. Dreibholz Intended status: Experimental T. Dreibholz
Expires: March 28, 2007 University of Duisburg-Essen Expires: September 6, 2007 University of Duisburg-Essen
September 24, 2006 March 5, 2007
Reliable Server Pooling Policies Reliable Server Pooling Policies
draft-ietf-rserpool-policies-03.txt draft-ietf-rserpool-policies-04.txt
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
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 ENRP Pooling including considerations for implementing them at ENRP
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. Non-Adaptive 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. ENRP Server Considerations . . . . . . . . . . . . . . 5 3.1.2. ENRP 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 . . . . . . . . . . . . . . . . . . . . . 6 3.2.1. Description . . . . . . . . . . . . . . . . . . . . . 5
3.2.2. ENRP Server Considerations . . . . . . . . . . . . . . 6 3.2.2. ENRP 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. ENRP Server Considerations . . . . . . . . . . . . . . 6 3.3.2. ENRP Server Considerations . . . . . . . . . . . . . . 6
3.3.3. Pool User Considerations . . . . . . . . . . . . . . . 7 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. ENRP Server Considerations . . . . . . . . . . . . . . 7 3.4.2. ENRP 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
3.5. Priority Policy . . . . . . . . . . . . . . . . . . . . . 8
3.5.1. Description . . . . . . . . . . . . . . . . . . . . . 8
3.5.2. ENRP Server Considerations . . . . . . . . . . . . . . 8
3.5.3. Pool Element Considerations . . . . . . . . . . . . . 8
3.5.4. Pool Member Selection Policy Parameter . . . . . . . . 8
4. Adaptive 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. ENRP Server Considerations . . . . . . . . . . . . . . 8 4.1.2. ENRP Server Considerations . . . . . . . . . . . . . . 9
4.1.3. Pool User Considerations . . . . . . . . . . . . . . . 8 4.1.3. Pool User Considerations . . . . . . . . . . . . . . . 9
4.1.4. Pool Member Selection Policy Parameter . . . . . . . . 8 4.1.4. Pool Member Selection Policy Parameter . . . . . . . . 9
4.2. Least Used with Degradation Policy . . . . . . . . . . . . 9 4.2. Least Used with Degradation Policy . . . . . . . . . . . . 9
4.2.1. Description . . . . . . . . . . . . . . . . . . . . . 9 4.2.1. Description . . . . . . . . . . . . . . . . . . . . . 9
4.2.2. ENRP Server Considerations . . . . . . . . . . . . . . 9 4.2.2. ENRP Server Considerations . . . . . . . . . . . . . . 9
4.2.3. Pool User Considerations . . . . . . . . . . . . . . . 9 4.2.3. Pool User Considerations . . . . . . . . . . . . . . . 10
4.2.4. Pool Member Selection Policy Parameter . . . . . . . . 9 4.2.4. Pool Member Selection Policy Parameter . . . . . . . . 10
4.3. Priority Least Used Policy . . . . . . . . . . . . . . . . 10 4.3. Priority Least Used Policy . . . . . . . . . . . . . . . . 10
4.3.1. Description . . . . . . . . . . . . . . . . . . . . . 10 4.3.1. Description . . . . . . . . . . . . . . . . . . . . . 10
4.3.2. ENRP Server Considerations . . . . . . . . . . . . . . 10 4.3.2. ENRP Server Considerations . . . . . . . . . . . . . . 10
4.3.3. Pool User Considerations . . . . . . . . . . . . . . . 10 4.3.3. Pool User Considerations . . . . . . . . . . . . . . . 11
4.3.4. Pool Member Selection Policy Parameter . . . . . . . . 11 4.3.4. Pool Member Selection Policy Parameter . . . . . . . . 11
4.4. Randomized Least Used Policy . . . . . . . . . . . . . . . 11 4.4. Randomized Least Used Policy . . . . . . . . . . . . . . . 11
4.4.1. Description . . . . . . . . . . . . . . . . . . . . . 11 4.4.1. Description . . . . . . . . . . . . . . . . . . . . . 11
4.4.2. ENRP Server Considerations . . . . . . . . . . . . . . 11 4.4.2. ENRP Server Considerations . . . . . . . . . . . . . . 11
4.4.3. Pool User Considerations . . . . . . . . . . . . . . . 11 4.4.3. Pool User Considerations . . . . . . . . . . . . . . . 12
4.4.4. Pool Member Selection Policy Parameter . . . . . . . . 11 4.4.4. Pool Member Selection Policy Parameter . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Reference Implementation . . . . . . . . . . . . . . . . . . . 12 7. Reference Implementation . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
Intellectual Property and Copyright Statements . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 16
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 adaptive and non-adaptive. The Therefore, we classify them as adaptive and non-adaptive. The
selection of the pool user is performed by two different entities. selection of the pool user is performed by two different entities.
Some of the consequences for policies which are not stateless are Some of the consequences for policies which are not stateless are
described in Performance [11]. described in Performance [11].
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elements of the list have been used it should start from the elements of the list have been used it should start from the
beginning again until the information is out of date. beginning again until the information is out of date.
3.1.4. Pool Member Selection Policy Parameter 3.1.4. 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=0x1 | (reserved) | | Policy Type = 0x00000001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0.
3.2. Weighted Round Robin Policy 3.2. Weighted Round Robin Policy
3.2.1. Description 3.2.1. Description
The Weighted Round Robin (WRR) policy is a generalization of the RR The Weighted Round Robin (WRR) policy is a generalization of the RR
policy. If all weights are 1 then WRR is just RR. policy. If all weights are 1 then WRR is just RR.
3.2.2. ENRP Server Considerations 3.2.2. ENRP Server Considerations
The ENRP server SHOULD follow the same rules as for RR but initialize The ENRP server SHOULD follow the same rules as for RR but initialize
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The pool user SHOULD follow the same rules as for RR. The pool user SHOULD follow the same rules as for RR.
3.2.4. Pool Member Selection Policy Parameter 3.2.4. 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 = 0xc | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x2 | (reserved) | | Policy Type = 0x00000002 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight | | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0.
o Weight: Weight constant for the WRR process. o Weight: Weight constant for the WRR process.
3.3. Random Policy 3.3. Random Policy
3.3.1. Description 3.3.1. Description
The Random (RAND) policy is a very simple stateless policy. The Random (RAND) policy is a very simple stateless policy.
3.3.2. ENRP Server Considerations 3.3.2. ENRP Server Considerations
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randomly selecting one element from the list of pool elements randomly selecting one element from the list of pool elements
received from the ENRP server. received from the ENRP server.
3.3.4. Pool Member Selection Policy Parameter 3.3.4. 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=0x3 | (reserved) | | Policy Type = 0x00000003 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0.
3.4. Weighted Random Policy 3.4. Weighted Random Policy
3.4.1. Description 3.4.1. Description
The Weighted Random (WRAND) policy is a generalization of the RAND The Weighted Random (WRAND) policy is a generalization of the RAND
policy, adding a weight for each pool element entry. RAND is equal policy, adding a weight for each pool element entry. RAND is equal
to WRAND having all weights set to 1. to WRAND having all weights set to 1.
3.4.2. ENRP Server Considerations 3.4.2. ENRP Server Considerations
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selecting a pool element should be the ratio of the weight of that selecting a pool element should be the ratio of the weight of that
pool element to the sum of weights. pool element to the sum of weights.
3.4.3. Pool User Considerations 3.4.3. Pool User Considerations
Each time the pool user must select one pool element it does this by Each time the pool user must select one pool element it does this by
randomly selecting one element from the list of pool elements randomly selecting one element from the list of pool elements
received from the ENRP server. received from the ENRP server.
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 = 0xc | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x4 | (reserved) | | Policy Type = 0x00000004 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight | | Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Weight: Weight constant for the WRAND process.
3.5. Priority Policy
3.5.1. Description
The Priority (PRIO) policy can be used to select always a pool
element with the highest priority.
3.5.2. ENRP Server Considerations
The ENRP server MUST select the pool elements with the highest
priorities. They MUST be reported in decreasing order. If multiple
pool elements have the same priority, they may be listed in any
order.
3.5.3. Pool Element Considerations
The pool user MUST select the active pool element with the highest
priority.
3.5.4. Pool Member Selection Policy Parameter
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0xa | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0. o Reserved: 24 bits, SHOULD be set to 0.
o Weight: Weight constant for the WRAND process. o Priority: 32 bits, unsigned int. Larger numbers mean higher
priorities.
4. Adaptive 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. ENRP Server Considerations 4.1.2. ENRP Server Considerations
The ENRP server SHOULD select at most the requested number of pool The ENRP server SHOULD select at most the requested number of pool
elements. Their load values SHOULD be the lowest possible ones elements. Their load values SHOULD be the lowest possible ones
within the pool. Each element MUST NOT be reported more than once to within the pool. Each element MUST NOT be reported more than once to
the pool user. If there is a choice of equal-loaded pool elements, the pool user. If there is a choice of equal-loaded pool elements,
round robin selection SHOULD be made between these elements. The round robin selection SHOULD be made among these elements. The
returned list of pool elements MUST be sorted ascending by load returned list of pool elements MUST be sorted ascending by load
value. value.
4.1.3. Pool User Considerations 4.1.3. 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 ENRP server. A subsequent call for list in the order returned by the ENRP server. A subsequent call for
handle resolution may result in the same list. Thereofore, it is handle resolution may result in the same list. Thereofore, 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 9, line 4 skipping to change at page 9, line 24
4.1.3. Pool User Considerations 4.1.3. 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 ENRP server. A subsequent call for list in the order returned by the ENRP server. A subsequent call for
handle resolution may result in the same list. Thereofore, it is handle resolution may result in the same list. Thereofore, 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.
4.1.4. Pool Member Selection Policy Parameter 4.1.4. 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 = 0xc | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x5 | (reserved) | | Policy Type = 0x40000001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0.
o Load: Current load of the pool element. o Load: Current load of the pool element.
4.2. Least Used with Degradation Policy 4.2. Least Used with Degradation Policy
4.2.1. Description 4.2.1. Description
The Least Used with Degradation (LUD) policy extends the LU policy by The Least Used with Degradation (LUD) policy extends the LU policy by
a load degradation value describing the pool element's load increment a load degradation value describing the pool element's load increment
when a new service association is accepted. when a new service association is accepted.
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a load degradation value describing the pool element's load increment a load degradation value describing the pool element's load increment
when a new service association is accepted. when a new service association is accepted.
4.2.2. ENRP Server Considerations 4.2.2. ENRP Server Considerations
For every pool element entry, a degradation counter MUST be stored. For every pool element entry, a degradation counter MUST be stored.
When a pool element entry is added or updated by registration or When a pool element entry is added or updated by registration or
reregistration, this counter MUST be set to 0. When an entry is reregistration, this counter MUST be set to 0. When an entry is
selected for being returned to a pool user, the internal degradation selected for being returned to a pool user, the internal degradation
counter MUST be incremented by the entry's load degradation constant. counter MUST be incremented by the entry's load degradation constant.
The selection of pool element entries is handled like for LU, except The selection of pool element entries is handled like for LU, except
that the selected pool element entries SHOULD have the lowest that the selected pool element entries SHOULD have the lowest
possible sum of load value + degradation counter. possible sum of load value + degradation counter.
4.2.3. Pool User Considerations 4.2.3. Pool User Considerations
See LU policy. See LU policy.
4.2.4. Pool Member Selection Policy Parameter 4.2.4. 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 = 0x10 | | Param Type = 0x6 | Length = 0x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x6 | (reserved) | | Policy Type = 0x40000002 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load Degradation | | Load Degradation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 8 bits, SHOULD be set to 0.
o Load: Current load of the pool element. o Load: Current load of the pool element.
o Load Degradation: Load Degradation constant of the pool element. o Load Degradation: Load Degradation constant of the pool element.
4.3. Priority Least Used Policy 4.3. Priority Least Used Policy
4.3.1. Description 4.3.1. Description
The Priority Least Used (PLU) policy uses load information provided The Priority Least Used (PLU) policy uses load information provided
by the pool elements to select the lowest-loaded pool elements within by the pool elements to select the lowest-loaded pool elements within
the pool under the assumption that a new application request is the pool under the assumption that a new application request is
skipping to change at page 10, line 43 skipping to change at page 11, line 5
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. ENRP Server Considerations 4.3.2. ENRP Server Considerations
The ENRP server SHOULD select at most the requested number of pool The ENRP 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 equal- more than once to the pool user. If there is a choice of equal-
valued pool element entries, round robin SHOULD be made between these valued pool element entries, round robin SHOULD be made among 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 ENRP server. A subsequent call for list in the order returned by the ENRP server. A subsequent call for
handle resolution may result in the same list. Therefore, it is handle 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.
4.3.4. Pool Member Selection Policy Parameter 4.3.4. 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 = 0x10 | | Param Type = 0x6 | Length = 0x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x7 | (reserved) | | Policy Type = 0x40000003 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load Degradation | | Load Degradation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 8 bits, SHOULD be set to 0.
o Load: Current load of the pool element. o Load: Current load of the pool element.
o Load Degradation: Load Degradation constant of the pool element. o Load Degradation: Load Degradation constant of the pool element.
4.4. Randomized Least Used Policy 4.4. Randomized Least Used Policy
4.4.1. Description 4.4.1. Description
The Randomized Least Used (RLU) policy combines LU and WRAND. That The Randomized Least Used (RLU) policy combines LU and WRAND. That
is, the pool element entries are selected randomly; the probability is, the pool element entries are selected randomly; the probability
for a pool element entry to be selected is the ratio of 100%-load to for a pool element entry to be selected is the ratio of 100%-load to
skipping to change at page 12, line 4 skipping to change at page 12, line 10
4.4.2. ENRP Server Considerations 4.4.2. ENRP Server Considerations
The ENRP server SHOULD behave like WRAND, having every PE's weight The ENRP server SHOULD behave like WRAND, having every PE's weight
set to (0xffffffff - Load value provided by the pool element). set to (0xffffffff - Load value provided by the pool element).
4.4.3. Pool User Considerations 4.4.3. Pool User Considerations
See WRAND policy. See WRAND policy.
4.4.4. Pool Member Selection Policy Parameter 4.4.4. 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 = 0x7 | Length = 0xc | | Param Type = 0x7 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x9 | (reserved) | | Policy Type = 0x40000004 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 8 bits, SHOULD be set to 0.
o Load: Current load of the pool element. o Load: Current load of the pool element.
5. Security Considerations 5. Security Considerations
The security threats regarding RSerPool have been analyzed in The security threats regarding RSerPool have been analyzed in
RSerPool threats [6]. The server policy descriptions in this RSerPool threats [6]. The server policy descriptions in this
document do not add any other threats. document do not add any other threats.
6. IANA Considerations 6. IANA Considerations
IANA keeps a list of Policy Types which are 1 byte values. The The IANA keeps a list of Policy Types which are 4 byte values. The
Policy values used in this document are: format of the policy type value is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X|A| Policy Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o X: If set to 1, the policy is user-defined and not standardized.
All standards policies reserved by the IETF use X=0.
o A: If set to 1, the policy is adaptive. Otherwise, it is non-
adaptive.
o Policy Number: The actual number of the policy.
The Policy Type values used in this document are:
Value Policy Value Policy
----- --------- ----- ---------
0x00 (reserved by IETF) 0x00000000 (reserved by IETF)
0x01 Round Robin 0x00000001 Round Robin
0x02 Weighted Round Robin 0x00000002 Weighted Round Robin
0x03 Random 0x00000003 Random
0x04 Weighted Random 0x00000004 Weighted Random
0x05 Least Used 0x00000005 Active/Passive
0x06 Least Used with Degradation 0x00000006 (reserved by IETF)
0x07 Priority Least Used ...
0x09 Randomized Least Used 0x3fffffff (reserved by IETF)
others (reserved by IETF)
0x40000000 (reserved by IETF)
0x40000001 Least Used
0x40000002 Least Used with Degradation
0x40000003 Priority Least Used
0x40000004 Randomized Least Used
0x40000005 (reserved by IETF)
...
0x7fffffff (reserved by IETF)
0x80000000 (user-defined, non-standard policy)
...
0xffffffff (user-defined, non-standard policy)
7. Reference Implementation 7. Reference Implementation
The reference implementation of RSerPool and the policies described The reference implementation of RSerPool and the policies described
in this document is available at [7]. in this document is available at [7].
8. References 8. References
8.1. Normative References 8.1. 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",
RFC 3668, February 2004. RFC 3668, February 2004.
[3] Stewart, R., "Aggregate Server Access Protocol (ASAP) and [3] Stewart, R., "Aggregate Server Access Protocol (ASAP) and
Endpoint Handlespace Redundancy Protocol (ENRP) Parameters", Endpoint Handlespace Redundancy Protocol (ENRP) Parameters",
draft-ietf-rserpool-common-param-10 (work in progress), draft-ietf-rserpool-common-param-11 (work in progress),
February 2006. October 2006.
[4] Stewart, R., "Aggregate Server Access Protocol (ASAP)", [4] Stewart, R., "Aggregate Server Access Protocol (ASAP)",
draft-ietf-rserpool-asap-13 (work in progress), February 2006. draft-ietf-rserpool-asap-15 (work in progress), January 2007.
[5] Stewart, R., "Endpoint Handlespace Redundancy Protocol (ENRP)", [5] Stewart, R., "Endpoint Handlespace Redundancy Protocol (ENRP)",
draft-ietf-rserpool-enrp-13 (work in progress), February 2006. draft-ietf-rserpool-enrp-15 (work in progress), January 2007.
[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-05 (work in progress), July 2005. draft-ietf-rserpool-threats-06 (work in progress),
November 2006.
8.2. Informative References 8.2. Informative References
[7] Dreibholz, T., "Thomas Dreibholz's RSerPool Page", [7] Dreibholz, T., "Thomas Dreibholz's RSerPool Page",
URL: http://tdrwww.exp-math.uni-essen.de/dreibholz/rserpool/. URL: http://tdrwww.exp-math.uni-essen.de/dreibholz/rserpool/.
[8] Dreibholz, T. and E. Rathgeb, "On the Performance of Reliable [8] Dreibholz, T. and E. Rathgeb, "On the Performance of Reliable
Server Pooling Systems", Proceedings of the 30th IEEE Local Server Pooling Systems", Proceedings of the 30th IEEE Local
Computer Networks Conference, November 2005. Computer Networks Conference, November 2005.
skipping to change at page 15, line 7 skipping to change at page 16, line 7
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/
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
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, THE IETF TRUST AND
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE 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.
Intellectual Property Intellectual Property
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
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made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
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