draft-ietf-rserpool-comp-03.txt   draft-ietf-rserpool-comp-04.txt 
RserPool Working Group J. Loughney (ed.) RserPool Working Group J. Loughney (ed.)
INTERNET DRAFT M. Stillman INTERNET DRAFT M. Stillman
Nokia Nokia
Q. Xie Q. Xie
Motorola Motorola
R. Stewart R. Stewart
Cisco Cisco
Issued: March 1, 2002 Issued: June 30, 2002
Expires: September 1, 2002 Expires: December 30, 2002
Comparison of Protocols for Reliable Server Pooling Comparison of Protocols for Reliable Server Pooling
<draft-ietf-rserpool-comp-03.txt> <draft-ietf-rserpool-comp-04.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026. of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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Copyright (C) The Internet Society 2002. All Rights Reserved. Copyright (C) The Internet Society 2002. All Rights Reserved.
Abstract Abstract
This document compares protocols that may be applicable for Reliable This document compares protocols that may be applicable for Reliable
Server Pooling problem space. This document discusses the usage and Server Pooling problem space. This document discusses the usage and
applicability of these protocols for Reliable Server Pooling. applicability of these protocols for Reliable Server Pooling.
Abstract..............................................................1 Abstract..............................................................1
1 Introduction........................................................3 1 Introduction.......................................................3
1.1 Overview........................................................3 1.1 Overview........................................................3
1.2 Terminology.....................................................3 1.2 Terminology.....................................................3
2 Relation to Other Solutions.........................................4 2 Relation to Other Solutions........................................4
2.1 CORBA...........................................................4 2.1 CORBA...........................................................4
2.2 DNS.............................................................4 2.2 DNS.............................................................4
2.2.1 Requirements.................................................5 2.2.1 Requirements.................................................5
2.2.2 Technical Issues.............................................5 2.2.2 Technical Issues.............................................5
2.2.3 Name/Address Resolution......................................7 2.2.3 Name/Address Resolution......................................7
2.3 Service Location Protocol (SLP).................................8 2.3 Service Location Protocol (SLP).................................8
2.3.1 Introduction.................................................8 2.3.1 Introduction.................................................8
2.3.2 What to Use..................................................8 2.3.2 What to Use..................................................8
2.3.3 Summary......................................................9 2.3.3 Summary......................................................9
3 ASAP and ENRP......................................................10 3 ASAP and ENRP.....................................................10
3.1 ASAP...........................................................10 3.1 ASAP...........................................................10
3.2 ENRP...........................................................11 3.2 ENRP...........................................................11
4 Comparison Against Requirements....................................11 4 Comparison Against Requirements...................................11
5 Security Concerns..................................................12 5 Security Concerns.................................................12
6 Acknowledgements...................................................12 6 Acknowledgements..................................................12
7 References.........................................................12 7 References........................................................12
8 Authors' Addresses.................................................13 8 Authors' Addresses................................................13
Full Copyright Statement.............................................13 Full Copyright Statement............................................13
1 Introduction 1 Introduction
1.1 Overview 1.1 Overview
In creating a solution to provide reliable server pools [RSER-ARCH], In creating a solution to provide reliable server pools [RSER-ARCH],
there are a number of existing protocols, which appear to have there are a number of existing protocols, which appear to have
similar properties as to what RSerPool is trying to accomplish. similar properties as to what RSerPool is trying to accomplish.
This document discusses the applicability of these protocols in This document discusses the applicability of these protocols in
meeting the requirements of Reliable Server Pooling [RFC3237]. meeting the requirements of Reliable Server Pooling [RFC3237].
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2.1 CORBA 2.1 CORBA
Often referred to as a Distributed Processing Environment (DPE), Often referred to as a Distributed Processing Environment (DPE),
CORBA was mainly designed to provide location transparency for CORBA was mainly designed to provide location transparency for
distributed applications. CORBA's distribution model encourages an distributed applications. CORBA's distribution model encourages an
object-based view, i.e., each communication endpoint is normally an object-based view, i.e., each communication endpoint is normally an
object. object.
CORBA has a number of variants, such as fault-tolerant CORBA, Real- CORBA has a number of variants, such as fault-tolerant CORBA, Real-
time CORBA, etc. CORBA has been used in a number of situations, for time CORBA, etc. CORBA has been used in a number of situations, for
example, Real-time CORBA has been usedin fighter aircraft and weapon example, Real-time CORBA has been used in fighter aircraft and
systems. Additionally, CORBA has been implentented in a wide range weapon systems. Additionally, CORBA has been implentented in a wide
of devices, from attack submarines to Palm Pilots - the MICO open range of devices, from attack submarines to Palm Pilots - the MICO
source ORB has been ported to the Palm Pilot, and the client-only open source ORB has been ported to the Palm Pilot, and the client-
application is 45 KB. only application is 45 KB.
Currently, the applicability of CORBA is unclear, and interaction Currently, the applicability of CORBA is unclear, and interaction
with other Internet protocols, such as AAA, IPsec and Ipv6 may be with other Internet protocols, such as AAA, IPsec and IPv6 may be
problematic. problematic.
2.2 DNS 2.2 DNS
This section will answer the question why DNS is not appropriate as This section will answer the question why DNS is not appropriate as
the sole solution for RSerPool. In addition, it highlights specific the sole solution for RSerPool. In addition, it highlights specific
technical differences between RSerPool and DNS. technical differences between RSerPool and DNS.
During the 49th IETF December 13, 2000 plenary meeting Randy Bush During the 49th IETF December 13, 2000 plenary meeting Randy Bush
presented a talk entitled "The DNS Today: Are we overloading the presented a talk entitled "The DNS Today: Are we overloading the
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Based on this, DNS can only really support stochastic load Based on this, DNS can only really support stochastic load
balancing, redirecting clients to servers randomly as various caches balancing, redirecting clients to servers randomly as various caches
in various resolvers expire at random (although small) intervals. in various resolvers expire at random (although small) intervals.
DNS offers excellent network scalability but poor control over load DNS offers excellent network scalability but poor control over load
balance. balance.
As mentioned previously, the issue of doing DNS-based dynamic load As mentioned previously, the issue of doing DNS-based dynamic load
balancing on short time scales will have impacts on third parties, balancing on short time scales will have impacts on third parties,
due to the presence of stub resolvers. due to the presence of stub resolvers.
2.2.2.4 Heartbeating / Status Monitoring 2.2.2.4 Heartbeating & Status Monitoring
DNS does not incorporate an application layer heartbeat. DNS does not incorporate an application layer heartbeat.
Heartbeating would dramatically boost traffic levels, and given the Heartbeating would dramatically boost traffic levels, and given the
unavoidable third party dependencies of DNS, the resulting loading unavoidable third party dependencies of DNS, the resulting loading
would be unacceptable. It is passive in the sense that it does not would be unacceptable. It is passive in the sense that it does not
monitor or store information on the state of the host such as monitor or store information on the state of the host such as
whether the host is up or down or what kind of load it is currently whether the host is up or down or what kind of load it is currently
experiencing. experiencing.
RSerPool SHOULD monitor the state of each server entity on various RSerPool SHOULD monitor the state of each server entity on various
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