draft-ietf-rserpool-policies-02.txt   draft-ietf-rserpool-policies-03.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: August 6, 2006 T. Dreibholz Intended status: Informational T. Dreibholz
University of Duisburg-Essen Expires: March 28, 2007 University of Duisburg-Essen
February 2, 2006 September 24, 2006
Reliable Server Pooling Policies Reliable Server Pooling Policies
draft-ietf-rserpool-policies-02.txt draft-ietf-rserpool-policies-03.txt
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Copyright Notice Copyright Notice
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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 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 Name 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 . . . . . . . . . . . . . . . . . . . . . 5 3.2.1. Description . . . . . . . . . . . . . . . . . . . . . 6
3.2.2 Name 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 Name Server Considerations . . . . . . . . . . . . . . 6 3.3.2. ENRP Server Considerations . . . . . . . . . . . . . . 6
3.3.3 Pool User Considerations . . . . . . . . . . . . . . . 6 3.3.3. Pool User Considerations . . . . . . . . . . . . . . . 7
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. 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
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 Name Server Considerations . . . . . . . . . . . . . . 8 4.1.2. ENRP 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 . . . . . . . . . . . . 9
4.2.1 Description . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. Description . . . . . . . . . . . . . . . . . . . . . 9
4.2.2 Name Server Considerations . . . . . . . . . . . . . . 9 4.2.2. ENRP 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 . . . . . . . . . . . . . . . . 10
4.3.1 Description . . . . . . . . . . . . . . . . . . . . . 9 4.3.1. Description . . . . . . . . . . . . . . . . . . . . . 10
4.3.2 Name Server Considerations . . . . . . . . . . . . . . 10 4.3.2. ENRP 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 . . . . . . . . 11
4.4 Randomized Least Used Policy . . . . . . . . . . . . . . . 10 4.4. Randomized Least Used Policy . . . . . . . . . . . . . . . 11
4.4.1 Description . . . . . . . . . . . . . . . . . . . . . 10 4.4.1. Description . . . . . . . . . . . . . . . . . . . . . 11
4.4.2 Name Server Considerations . . . . . . . . . . . . . . 11 4.4.2. ENRP 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 . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7. Reference Implementation . . . . . . . . . . . . . . . . . . . 12
7.1 Normative References . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2 Informative References . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 15
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].
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. ENRP 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. 0x00000000 states, that the pool
element is not utilized (0%), 0xffffff states that it is fully element is not utilized (0%), 0xffffffff states that it is fully
utilized (100%). Defining what utilization means is application- utilized (100%). Defining what utilization means is application-
dependent and out of the scope of RSerPool. However, it is required dependent and out of the scope of RSerPool. However, it is required
that all pool elements of the same pool using load information have that all pool elements of the same pool using load 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).
Defining what value weights compare is application-dependent and out Defining what value weights compare is application-dependent and out
of the scope of RSerPool. However, it is required that all pool of the scope of RSerPool. However, it is required that all pool
elements of the same pool using weight information have the same elements of the same pool using weight information have the same
definition of weight. definition of weight.
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. Non-Adaptive 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. ENRP Server Considerations
The name server SHOULD hold the pool elements of each server pool in The ENRP server SHOULD hold the pool elements of each server pool in
a circular list and SHOULD store a pointer to one of the elements, a circular list and SHOULD store a pointer to one of the elements,
called the head. On reception of a name resolution request the name called the head. On reception of a handle resolution request the
server SHOULD return the pool elements from the circular list ENRP server SHOULD return the pool elements from the circular list
starting with head. Then head SHOULD be advanced by one element. starting with head. Then head SHOULD be advanced by one element.
Using this algorithm it is made sure that not all lists presented to Using this algorithm it is made sure that not all lists presented to
the pool users start with the same element. the pool users start with the same element.
3.1.3 Pool User Considerations 3.1.3. Pool User Considerations
A pool user SHOULD use the list of pool elements returned by the name A pool user SHOULD use the list of pool elements returned by the ENRP
server in a round robin fashion, starting with the first. If all server in a round robin fashion, starting with the first. If all
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=0x1 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0. 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 Name Server Considerations 3.2.2. ENRP Server Considerations
The name server SHOULD follow the same rules as for RR but initialize The ENRP server SHOULD follow the same rules as for RR but initialize
and modify the circular list differently. The name server puts each and modify the circular list differently. The ENRP server puts each
pool element possibly multiple times into the list such that: pool element possibly multiple times into the list such that:
o The ratio of the number of occurrences of a pool element to the o The ratio of the number of occurrences of a pool element to the
list length is the same as the ratio of the weight of that pool list length is the same as the ratio of the weight of that pool
element to the sum of weights. element to the sum of weights.
o Each pool element is inserted as distributed as possible in the o Each pool element is inserted as distributed as possible in the
circular list. circular list.
3.2.3 Pool User Considerations 3.2.3. Pool User Considerations
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 = 0x8 | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x2 | Weight | | Policy=0x2 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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 Name Server Considerations 3.3.2. ENRP Server Considerations
The name server selects at most the requested number of pool elements The ENRP server selects at most the requested number of pool elements
from the list of pool elements. Each element MUST NOT be reported from the list of pool elements. Each element MUST NOT be reported
more than once to the pool user. more than once to the pool user.
3.3.3 Pool User Considerations 3.3.3. 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 name 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=0x3 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0. 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 Name Server Considerations 3.4.2. ENRP Server Considerations
The name server SHOULD select at most the requested number of pool The ENRP server SHOULD select at most the requested number of pool
elements randomly from the list of pool elements. Each element MUST elements randomly from the list of pool elements. Each element MUST
NOT be reported more than once to the pool user. The probability of NOT be reported more than once to the pool user. The probability of
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 name 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 = 0x8 | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x4 | Weight | | Policy=0x4 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Reserved: 24 bits, SHOULD be set to 0.
o Weight: Weight constant for the WRAND process. o Weight: Weight constant for the WRAND process.
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 Name Server Considerations 4.1.2. ENRP Server Considerations
The name 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 between 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 name server. A subsequent call for list in the order returned by the ENRP server. A subsequent call for
name 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 = 0x8 | | Param Type = 0x6 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x5 | Load | | Policy=0x5 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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.
4.2.2 Name 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 = 0xc | | Param Type = 0x6 | Length = 0x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x6 | Load | | Policy=0x6 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (reserved) | Load Degradation | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load Degradation |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Load: Current load of the pool element.
o Reserved: 8 bits, SHOULD be set to 0. o Reserved: 8 bits, SHOULD be set to 0.
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
accepted by the pool elements. Therefore, the pool elements also accepted by the pool elements. Therefore, the pool elements also
have to specify load degradation information. have to specify load degradation information.
Example: Pool elements A and B are loaded by 50%, but the load of A Example: Pool elements A and B are loaded by 50%, but the load of A
will increase due to a new application request only by 10% while B will increase due to a new application request only by 10% while B
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. ENRP Server Considerations
The name 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 between 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 ENRP server. A subsequent call for
name 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 = 0xc | | Param Type = 0x6 | Length = 0x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x7 | Load | | Policy=0x7 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (reserved) | Load Degradation | | Load |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
the sum of all pool elements' load values. the sum of all pool elements' load values.
4.4.2 Name Server Considerations 4.4.2. ENRP Server Considerations
The name server SHOULD behave like WRAND, having every PE's weight The ENRP server SHOULD behave like WRAND, having every PE's weight
set to (0xffffff - 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 = 0x8 | | Param Type = 0x7 | Length = 0xc |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy=0x9 | Load | | Policy=0x9 | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
skipping to change at page 11, line 50 skipping to change at page 12, line 41
0x01 Round Robin 0x01 Round Robin
0x02 Weighted Round Robin 0x02 Weighted Round Robin
0x03 Random 0x03 Random
0x04 Weighted Random 0x04 Weighted Random
0x05 Least Used 0x05 Least Used
0x06 Least Used with Degradation 0x06 Least Used with Degradation
0x07 Priority Least Used 0x07 Priority Least Used
0x09 Randomized Least Used 0x09 Randomized Least Used
others (reserved by IETF) others (reserved by IETF)
7. References 7. Reference Implementation
7.1 Normative References The reference implementation of RSerPool and the policies described
in this document is available at [7].
8. 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-09 (work in progress), I-D draft-ietf-rserpool-common-param-10 (work in progress),
Status active, IETF Datatracker State AD is watching, Intended February 2006.
Status None, Responsible AD Jon Peterson, July 2005.
[4] Stewart, R., "Aggregate Server Access Protocol (ASAP)", [4] Stewart, R., "Aggregate Server Access Protocol (ASAP)",
draft-ietf-rserpool-asap-12 (work in progress), I-D draft-ietf-rserpool-asap-13 (work in progress), February 2006.
Status active, IETF Datatracker State AD is watching, Intended
Status None, Responsible AD Jon Peterson, July 2005.
[5] Stewart, R., "Endpoint Handlespace Redundancy Protocol (ENRP)", [5] Stewart, R., "Endpoint Handlespace Redundancy Protocol (ENRP)",
draft-ietf-rserpool-enrp-12 (work in progress), I-D draft-ietf-rserpool-enrp-13 (work in progress), February 2006.
Status active, IETF Datatracker State AD is watching, Intended
Status None, Responsible AD Jon Peterson, July 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-05 (work in progress), I-D draft-ietf-rserpool-threats-05 (work in progress), July 2005.
Status iesg, IETF Datatracker State IESG Evaluation :: Point
Raised - writeup needed, Intended Status Informational,
Responsible AD Jon Peterson, July 2005.
7.2 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.
[9] Dreibholz, T. and E. Rathgeb, "The Performance of Reliable [9] Dreibholz, T. and E. Rathgeb, "The Performance of Reliable
Server Pooling Systems in Different Server Capacity Scenarios", Server Pooling Systems in Different Server Capacity Scenarios",
skipping to change at page 14, line 5 skipping to change at page 15, line 5
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 Full Copyright Statement
Copyright (C) The Internet Society (2006).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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
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on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 14, line 29 skipping to change at page 15, line 45
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
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The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
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 provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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