draft-ietf-ieprep-domain-req-06.txt   rfc4375.txt 
Internet Engineering Task Force Ken Carlberg Network Working Group K. Carlberg
Request for Comments: 4375 G11
Nov 17, 2005 Category: Informational January 2006
Emergency Telecommunications Services (ETS) Requirements Emergency Telecommunications Services (ETS) Requirements
for a Single Administrative Domain for a Single Administrative Domain
<draft-ietf-ieprep-domain-req-06.txt>
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
Abstract Abstract
This document presents a list of requirements in support of Emergency This document presents a list of requirements in support of Emergency
Telecommunications Service (ETS) within a single administrative Telecommunications Service (ETS) within a single administrative
domain. This document is an extension of the General Requirements of domain. This document focuses on a specific set of administrative
[rfc3689] and focuses on a more specific set of administrative
constraints and scope. Solutions to these requirements are not constraints and scope. Solutions to these requirements are not
presented in this document. presented in this document.
1. Introduction 1. Introduction
The objective of this document is to define a set of requirements The objective of this document is to define a set of requirements
that support ETS within a single domain. There have been a number of that support ETS within a single domain. There have been a number of
discussions in the IEPREP mailing list, as well as working group discussions in the IEPREP mailing list, as well as working group
meetings, that have questioned the utility of a given mechanism to meetings, that have questioned the utility of a given mechanism to
support ETS. Many have advocated over-provisioning, while others support ETS. Many have advocated over-provisioning, while others
skipping to change at page 3, line 8 skipping to change at page 2, line 36
(ISP) is an example of a transit domain. (ISP) is an example of a transit domain.
Stub Domain: This is an administrative domain that is either the Stub Domain: This is an administrative domain that is either the
source or the destination of a flow of IP packets. As a general source or the destination of a flow of IP packets. As a general
rule, it does not forward traffic that is destined for other rule, it does not forward traffic that is destined for other
domains. The odd exception to this statement is the case of domains. The odd exception to this statement is the case of
Mobile IP and its use of "dog-leg" routing to visiting hosts Mobile IP and its use of "dog-leg" routing to visiting hosts
located in foreign networks. An enterprise network is an example located in foreign networks. An enterprise network is an example
of a stub domain. of a stub domain.
1.1 Previous Work 1.1. Previous Work
A list of General Requirements for support of ETS is presented in A list of general requirements for support of ETS is presented in
[rfc3689]. The document articulates requirements when considering [RFC3689]. The document articulates requirements when considering
the broad case of supporting ETS over the Internet. Since that the broad case of supporting ETS over the Internet. Since that
document is not constrained to specific applications, administrative document is not constrained to specific applications, administrative
boundaries, or scenarios, the requirements contained within it tend boundaries, or scenarios, the requirements contained within it tend
to be quite general in their description and scope. This follows the to be quite general in their description and scope. This follows the
philosophy behind its inception in that the General Requirements are philosophy behind its inception in that the general requirements are
meant to be a baseline followed (if necessary) by more specific meant to be a baseline followed (if necessary) by more specific
requirements that pertain to a more narrow scope. requirements that pertain to a more narrow scope.
The requirements presented below in Section 3 are representative of The requirements presented below in Section 3 are representative of
the more narrow scope of a single administrative domain. As in the the more narrow scope of a single administrative domain. As in the
case of [rfc3689], the requirements articulated in this document case of [RFC3689], the requirements articulated in this document
represent aspects to be taken into consideration when solutions are represent aspects to be taken into consideration when solutions are
being designed, specified, and deployed. Key words such as "MUST", being designed, specified, and deployed. Key words such as "MUST",
"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in [rfc2119]. interpreted as described in [RFC2119].
2. Scope 2. Scope
IETF standards that cover the resources within an administrative IETF standards that cover the resources within an administrative
domain are within the scope of this document. This includes domain are within the scope of this document. This includes
gateways, routers, servers, etc., that are located and administered gateways, routers, servers, etc., that are located and administered
within the domain. This document also does not restrict itself to a within the domain. This document also does not restrict itself to a
specific type of application such as Voice over IP. specific type of application such as Voice over IP.
QoS mechanisms are also within the scope of this document. These Quality of Service (QoS) mechanisms are also within the scope of this
mechanisms may reside at the application, transport, or IP network document. These mechanisms may reside at the application, transport,
layer. While QoS mechanisms may exist at the link/physical layer, or IP network layer. While QoS mechanisms may exist at the
this document would only consider potential mappings of labels or link/physical layer, this document only considers potential mappings
code points. of labels or code points.
Finally, since this document focuses on a single administrative Finally, since this document focuses on a single administrative
domain, we do not make any further distinction between transit and domain, we do not make any further distinction between transit and
stub domains within this document. stub domains within this document.
2.1 Out of Scope: 2.1. Out of Scope
Resources owned or operated by other administrative authorities are Resources owned or operated by other administrative authorities are
outside the scope of this document. One example are SIP servers that outside the scope of this document. One example is a SIP server that
operate in other domains. Another example are access links operates in other domains. Another example is an access link
connecting the stub domain and its provider. Controlling only 1/2 of connecting the stub domain and its provider. Controlling only 1/2 of
a link (the egress traffic from the stub) is considered insufficient a link (the egress traffic from the stub) is considered insufficient
for including inter-domain access links as a subject for this for including inter-domain access links as a subject for this
document. document.
3. Requirements 3. Requirements
It must be understood that all of the following requirements pertain It must be understood that all of the following requirements pertain
to mechanisms chosen by a domain's administrative authority to to mechanisms chosen by a domain's administrative authority to
specifically support ETS. If that authority chooses not to support specifically support ETS. If that authority chooses not to support
ETS or if these mechanisms exist within the domain exclusively for a ETS or if these mechanisms exist within the domain exclusively for a
different purpose, then the associated requirement does not apply. different purpose, then the associated requirement does not apply.
3.1 Label Mechanisms 3.1. Label Mechanisms
Application or transport layer label mechanisms used for ETS MUST be Application or transport layer label mechanisms used for ETS MUST be
extensible such that they can support more than one label. These extensible such that they can support more than one label. These
mechanism MUST avoid a single off/on type of label (e.g., a single mechanism MUST avoid a single off/on type of label (e.g., a single
bit). In addition, designers of such a mechanism MUST assume that bit). In addition, designers of such a mechanism MUST assume that
there may be more than one set of ETS users. there may be more than one set of ETS users.
Network layer label mechanisms used for ETS SHOULD be extensible such Network layer label mechanisms used for ETS SHOULD be extensible such
that they can support more than one label. We make this distinction that they can support more than one label. We make this distinction
in requirements because there may be fewer bits (a smaller field) in requirements because there may be fewer bits (a smaller field)
available at the network layer than in the transport or application available at the network layer than in the transport or application
layer. layer.
3.2 Proxies 3.2. Proxies
Proxies MAY set ETS labels on behalf of the source of a flow. This Proxies MAY set ETS labels on behalf of the source of a flow. This
may involve removing labels that have been set by upstream node(s). may involve removing labels that have been set by upstream node(s).
If proxies take such action, then the security measures discussed in If proxies take such action, then the security measures discussed in
[rfc3689] MUST be considered. More information about security in the [RFC3689] MUST be considered. More information about security in the
single domain context is found below in Section 5. single-domain context is found below in Section 5.
3.3 QoS mechanisms 3.3. QoS mechanisms
[rfc3689] defines a label as an identifier, and the set of [RFC3689] defines a label as an identifier, and the set of
characteristics associated with the label as policy. However, characteristics associated with the label as policy. However, QoS in
Quality of Service (QoS) in the traditional sense of delay or the traditional sense of delay or bandwidth is not automatically
bandwidth is not automatically bound to a label. MPLS [rfc3031] is bound to a label. MPLS [RFC3031] is an example of a labeling
an example of a labeling mechanism that can provide specific QoS or mechanism that can provide specific QoS or simply traffic engineering
simply traffic engineering of labeled flows. of labeled flows.
In the context of ETS, QoS mechanisms, at either the network or In the context of ETS, QoS mechanisms, at either the network or
application layer, SHOULD be used when networks cannot be over- application layer, SHOULD be used when networks cannot be over-
provisioned to satisfy high bursts of traffic load. Examples can provisioned to satisfy high bursts of traffic load. Examples can
involve bridging fiber networks to wireless subnetworks, or remote involve bridging fiber networks to wireless subnetworks, or remote
subnetworks connected over expensive bandwidth constrained wide area subnetworks connected over expensive bandwidth-constrained wide area
links. links.
Note well. Over-provisioning is a normal cost-effective practice Note well. Over-provisioning is a normal cost-effective practice
amongst network administrators/engineers. The amount of over- amongst network administrators/engineers. The amount of over-
provisioning can be a topic of debate. More in-depth discussion on provisioning can be a topic of debate. More in-depth discussion on
this topic is presented in the companion Framework document of this topic is presented in the companion Framework document [FRAME].
[frame].
3.4 Users 3.4. Users
Regarding existing IETF specified applications, augmentations in the Regarding existing IETF-specified applications, augmentations in the
form of labeling mechanisms to support ETS MUST NOT adversely affect form of labeling mechanisms to support ETS MUST NOT adversely affect
its legacy usage by non-ETS users. With respect to future its legacy usage by non-ETS users. With respect to future
applications, such labeling mechanisms SHOULD allow the application applications, such labeling mechanisms SHOULD allow the application
to support a "normal" (non-emergency) condition. to support a "normal" (non-emergency) condition.
3.5 Policy 3.5. Policy
Policy MUST be used to determine the percentage of resources of a Policy MUST be used to determine the percentage of resources of a
mechanism used to support the various (ETS and non-ETS) users. Under mechanism used to support the various (ETS and non-ETS) users. Under
certain conditions, this percentage MAY reach 100% for a specific set certain conditions, this percentage MAY reach 100% for a specific set
of users. However, we recommend that this "all-or-nothing" approach of users. However, we recommend that this "all-or-nothing" approach
be considered with great care. be considered with great care.
3.6 Discovery 3.6. Discovery
There should be a means of forwarding ETS labeled flows to those There should be a means of forwarding ETS labeled flows to those
mechanisms within the domain used to support ETS. Discovery mechanisms within the domain used to support ETS. Discovery
mechanisms SHOULD be used to determine where ETS labeled flows mechanisms SHOULD be used to determine where ETS labeled flows
(either data or control) are to be forwarded. (either data or control) are to be forwarded.
3.8 MIB 3.7. MIB
Management Information Bases (MIBs) SHOULD be defined for mechanisms Management Information Bases (MIBs) SHOULD be defined for mechanisms
specifically in place to support ETS. These MIBs MAY include objects specifically in place to support ETS. These MIBs MAY include objects
representing accounting, policy, authorization. representing accounting, policy, and authorization.
4. Issues 4. Issues
This section presents issues that arise in considering solutions for This section presents issues that arise in considering solutions for
the requirements that have been defined for Stub Domains that support the requirements that have been defined for stub domains that support
ETS. This section does not specify solutions nor is it to be ETS. This section does not specify solutions nor is it to be
confused with requirements. Subsequent documents that articulate a confused with requirements. Subsequent documents that articulate a
more specific set of requirements for a particular service may make a more specific set of requirements for a particular service may make a
statement about the following issues. statement about the following issues.
4.1 Alternative Services 4.1. Alternative Services
The form of the service provided to ETS users and articulated in the The form of the service provided to ETS users and articulated in the
form of policies may be realized in one of several forms. Better form of policies may be realized in one of several forms. Better
than best effort is probably the service that most ETS users would than best effort is probably the service that most ETS users would
expect when the communication system is stressed and overall quality expect when the communication system is stressed and overall quality
has degraded. However, the concept of best available service should has degraded. However, the concept of best available service should
also be considered under such stressed conditions. Further, a also be considered under such stressed conditions. Further, a
measure of degraded service may also be desirable to ensure a measure measure of degraded service may also be desirable to ensure a measure
of communication versus none. These services may be made available of communication versus none. These services may be made available
at the network or application layer. at the network or application layer.
4.2 Redundancy 4.2. Redundancy
The issue of making networks fault tolerant is important and yet not The issue of making networks fault tolerant is important and yet not
one that can be easily articulated in terms of requirements of one that can be easily articulated in terms of requirements of
protocols. Redundancy in connectivity and nodes (be it routers or protocols. Redundancy in connectivity and nodes (be it routers or
servers) is probably the most common approach taken by network servers) is probably the most common approach taken by network
administrators, and it can be assumed that administrative domains administrators, and it can be assumed that administrative domains
apply this approach in various degrees to there own resources. apply this approach in various degrees to their own resources.
5. Security Considerations 5. Security Considerations
This document recommends that readers review and follow the comments This document recommends that readers review and follow the comments
and requirements about security presented in [rfc3689]. Having said and requirements about security presented in [RFC3689]. Having said
that, there tends to be many instances where intra-domain security is that, there tend to be many instances where intra-domain security is
held at a lower standard (i.e., less stringent) that inter-domain held at a lower standard (i.e., less stringent) that inter-domain
security. For example, while administrators may allow telnet service security. For example, while administrators may allow telnet service
between resources within an administrative domain, they would only between resources within an administrative domain, they would only
allow SSH access from other domains. allow SSH access from other domains.
The disparity in security policy can be problematic when domains The disparity in security policy can be problematic when domains
offer services other than best effort for ETS users. Therefore, any offer services other than best effort for ETS users. Therefore, any
support within a domain for ETS should be accompanied by a detailed support within a domain for ETS should be accompanied by a detailed
security policy for users and administrators. security policy for users and administrators.
Given the "SHOULD" statement in section 3.8 concerning MIBs, there Given the "SHOULD" statement in Section 3.8 concerning MIBs, there
are a number of related security considerations that need to be are a number of related security considerations that need to be
brought to attention to the reader. Specifically, brought to attention to the reader. Specifically, the following:
- Most current deployments of SNMP are of versions prior to - Most current deployments of Simple Network Management Protocol
SNMPv3, even though there are well-known security (SNMP) are of versions prior to SNMPv3, even though there are
vulnerabilities in those versions of SNMP. well-known security vulnerabilities in those versions of SNMP.
- SNMP versions prior to SNMPv3 cannot support cryptographic - SNMP versions prior to SNMPv3 cannot support cryptographic
security mechanisms. Hence, any use of SNMP prior to security mechanisms. Hence, any use of SNMP prior to version 3
version 3 to write or modify MIB objects do so in a to write or modify MIB objects do so in a non-secure manner. As
non-secure manner. As a result, it may be best to constrain a result, it may be best to constrain the use of these objects to
the use of these objects to read-only by MIB managers. read-only by MIB managers.
- Finally, any MIB defining writable objects should carefully - Finally, any MIB defining writable objects should carefully
consider the security implications of an SNMP compromise on consider the security implications of an SNMP compromise on the
the mechanism(s) being controlled by those writable MIB mechanism(s) being controlled by those writable MIB objects.
objects.
6. Acknowledgements 6. Acknowledgements
Thanks to Ran Atkinson, James Polk, Scott Bradner, Jon Peterson, and Thanks to Ran Atkinson, James Polk, Scott Bradner, Jon Peterson, and
Ian Brown for comments on previous versions of this draft. Ian Brown for comments on previous versions of this document.
7. References
7.1 Normative Reference
[rfc3668] Bradner, S., "Intellectual Property Rights in IETF
technology", BCP 79, RFC 3668, February 2004
7.2 Informative References 7. Informative References
[rfc2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[rfc3031] Rosen, E., et. al., "Multiprotocol Label Switching [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Architecture", RFC3031, January 2001 Label Switching Architecture", RFC 3031, January 2001.
[rfc3689] Carlberg, K., Atkinson, R., "General Requirements for [RFC3689] Carlberg, K. and R. Atkinson, "General Requirements for
Emergency Telecommunications Service", RFC3689 Emergency Telecommunication Service (ETS)", RFC 3689,
Feb 2004 February 2004.
[frame] Carlberg, K., "A Framework for Supporting ETS in Stub [FRAME] Carlberg, K., "A Framework for Supporting Emergency
Domains", Internet Draft, Work in Progress, Telecommunications Services (ETS) Within a Single
draft-ieprep-domain-frame-02.txt, June 2003. Administrative Domain", Work in Progress, December 2005.
8. Author's Addresses Author's Address
Ken Carlberg Ken Carlberg
G11 G11
123a Versailles Circle 123a Versailles Circle
Baltimore, MD Baltimore, MD
USA USA
carlberg@g11.org.uk
Intellectual Property Statement EMail: carlberg@g11.org.uk
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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
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