draft-ietf-grow-unique-origin-as-01.txt   rfc6382.txt 
INTERNET-DRAFT Danny McPherson
Ryan Donnelly
Frank Scalzo
Verisign, Inc.
Expires: January 2012 July 2, 2011
Intended Status: Best Current Practice
Unique Per-Node Origin ASNs for Globally Anycasted Services Internet Engineering Task Force (IETF) D. McPherson
<draft-ietf-grow-unique-origin-as-01.txt> Request for Comments: 6382 R. Donnelly
BCP: 169 F. Scalzo
Category: Best Current Practice Verisign, Inc.
ISSN: 2070-1721 October 2011
Status of this Memo Unique Origin Autonomous System Numbers (ASNs)
per Node for Globally Anycasted Services
This Internet-Draft is submitted to IETF in full conformance with the Abstract
provisions of BCP 78 and BCP 79.
This document is subject to BCP 78 and the IETF Trust's Legal Provisions This document makes recommendations regarding the use of unique
Relating to IETF Documents (http://trustee.ietf.org/license-info) origin autonomous system numbers (ASNs) per node for globally
in effect on the date of publication of this document. Please anycasted critical infrastructure services in order to provide
review these documents carefully, as they describe your rights and routing system discriminators for a given anycasted prefix. Network
restrictions with respect to this document. Code Components management and monitoring techniques, or other operational
extracted from this document must include Simplified BSD License mechanisms, may employ this new discriminator in whatever manner best
text as described in Section 4.e of the Trust Legal Provisions and accommodates their operating environment.
are provided without warranty as described in the Simplified BSD
License.
Internet-Drafts are working documents of the Internet Engineering Task Status of This Memo
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months This memo documents an Internet Best Current Practice.
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at This document is a product of the Internet Engineering Task Force
http://www.ietf.org/1id-abstracts.html (IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
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BCPs is available in Section 2 of RFC 5741.
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http://www.rfc-editor.org/info/rfc6382.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
Abstract This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
This document makes recommendations regarding the use of unique (http://trustee.ietf.org/license-info) in effect on the date of
origin autonomous system numbers per node for globally anycasted publication of this document. Please review these documents
critical infrastructure services in order to provide routing system carefully, as they describe your rights and restrictions with respect
discriminators for a given anycasted prefix. Network management and to this document. Code Components extracted from this document must
monitoring techniques, or other operational mechanisms may employ include Simplified BSD License text as described in Section 4.e of
this new discriminator in whatever manner best accommodates their the Trust Legal Provisions and are provided without warranty as
operating environment. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction ....................................................2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology .....................................................4
3. Recommendation for Unique Origin ASNs. . . . . . . . . . . . . 7 3. Recommendation for Unique Origin ASNs ...........................5
4. Additional Recommendations for Globally Anycasted 4. Additional Recommendations for Globally Anycasted Services ......6
Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations .........................................7
5. Security Considerations. . . . . . . . . . . . . . . . . . . . 8 6. Deployment Considerations .......................................7
6. Deployment Considerations. . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements ................................................9
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 8. IANA Considerations .............................................9
8. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 11 9. References ......................................................9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 9.1. Normative References .......................................9
9.1. Normative References. . . . . . . . . . . . . . . . . . . . 11 9.2. Informative References .....................................9
9.2. Informative References. . . . . . . . . . . . . . . . . . . 11
10. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 12
1. Terminology
This document employs much of the following terminology, which was
taken in full from Section 2 of [RFC 4786].
Anycast: the practice of making a particular Service Address
available in multiple, discrete, autonomous locations, such that
datagrams sent are routed to one of several available locations.
Anycast Node: an internally-connected collection of hosts and
routers that together provide service for an anycast Service
Address. An Anycast Node might be as simple as a single host
participating in a routing system with adjacent routers, or it
might include a number of hosts connected in some more elaborate
fashion; in either case, to the routing system across which the
service is being anycast, each Anycast Node presents a unique path
to the Service Address. The entire anycast system for the service
consists of two or more separate Anycast Nodes.
Catchment: in physical geography, an area drained by a river, also
known as a drainage basin. By analogy, as used in this document,
the topological region of a network within which packets directed
at an Anycast Address are routed to one particular node.
Local-Scope Anycast: reachability information for the anycast
Service Address is propagated through a routing system in such a
way that a particular anycast node is only visible to a subset of
the whole routing system.
Local Node: an Anycast Node providing service using a Local-Scope
Anycast Address.
Global Node: an Anycast Node providing service using a Global-Scope
Anycast Address.
Global-Scope Anycast: reachability information for the anycast
Service Address is propagated through a routing system in such a
way that a particular anycast node is potentially visible to the
whole routing system.
Service Address: an IP address associated with a particular service
(e.g., the destination address used by DNS resolvers to reach a
particular authority server).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
2. Introduction 1. Introduction
IP anycasting [RFC 4786] has been deployed for an array of network IP anycasting [RFC4786] has been deployed for an array of network
services since the early 1990s. It provides a mechanism for a given services since the early 1990s. It provides a mechanism for a given
network resource to be available in a more distributed manner, network resource to be available in a more distributed manner,
locally and/or globally, with a more robust and resilient footprint, locally and/or globally, with a more robust and resilient footprint,
commonly yielding better localization and absorption of systemic commonly yielding better localization and absorption of systemic
query loads, as well as better protections in the face of DDoS query loads, as well as better protections in the face of distributed
attacks, network partitions, and other similar incidents. A large denial-of-service (DDoS) attacks, network partitions, and other
part of the Internet root DNS infrastructure, as well as many other similar incidents. A large part of the Internet root DNS
resources, has been anycasted for nearly a decade. infrastructure, as well as many other resources, has been anycasted
for nearly a decade.
While the benefits realized by anycasting network services is proven, While the benefits realized by anycasting network services is proven,
some issues do emerge with asserting routing system reachability for some issues do emerge with asserting routing system reachability for
a common network identifier from multiple locations. Specifically, a common network identifier from multiple locations. Specifically,
anycasting in BGP requires injection of reachability information in anycasting in BGP requires injection of reachability information in
the routing system for a common IP address prefix from multiple the routing system for a common IP address prefix from multiple
locations. These anycasted prefixes and network services have locations. These anycasted prefixes and network services have
traditionally employed a common origin autonomous system number (ASN) traditionally employed a common origin autonomous system number (ASN)
in order to preserve historically scarce 16-bit AS number space in order to preserve historically scarce 16-bit AS number space
utilized by BGP for routing domain identifiers in the global routing utilized by BGP for routing domain identifiers in the global routing
system. Additionally, a common origin AS number was used in order to system. Additionally, a common origin AS number was used in order to
ease management overhead of resource operations associated with ease management overhead of resource operations associated with
acquiring and maintaining multiple discrete AS numbers, as well as to acquiring and maintaining multiple discrete AS numbers as well as to
avoid triggering various operations- oriented reporting functions avoid triggering various operations-oriented reporting functions
aimed at identifying "inconsistent origin AS announcements" observed aimed at identifying "inconsistent origin AS announcements" observed
in the routing system. As a result, the representation of routing in the routing system. As a result, the representation of routing
system path attributes associated with those service instances, and system path attributes associated with those service instances, and
that anycasted prefix itself, typically bear no per-instance that anycasted prefix itself, typically bear no per-instance
discriminators in the routing system (i.e., within the network discriminators in the routing system (i.e., within the network
control plane itself). control plane itself).
Service level query capabilities may or may not provide a mechanism Service-level query capabilities may or may not provide a mechanism
to identify which anycast node responded to a particular query, to identify which anycast node responded to a particular query,
although this is likely both service (e.g., DNS or NTP) and although this is likely both service (e.g., DNS or NTP) and
implementation dependent. For example, NSD, Unbound, and BIND all implementation dependent. For example, Name Server Daemon (NSD),
provide 'hostname.bind or hostname.id' [HNAME] query support that Unbound, and BIND all provide 'hostname.bind or hostname.id'
enables service-level identification of a given server. Tools such [RFC4892] [RFC5001] query support that enables service-level
as traceroute are also used to determine which location a given query identification of a given server. Tools such as traceroute are also
is being routed to, although it may not reveal local-scope anycast used to determine to which location a given query is being routed,
instances, or if there are multiple servers within a given anycast although it may not reveal local-scope anycast instances, or if there
node, which of the servers responded to a given query, in particular are multiple servers within a given anycast node, which of the
when multiple servers within an anycast node are connected to a servers responded to a given query, in particular, when multiple
single IP router. When utilizing these service level capabilities, servers within an anycast node are connected to a single IP router.
query responses are typically both deterministic and inherently When utilizing these service-level capabilities, query responses are
topology-dependent, however, these service level identifiers at the typically both deterministic and inherently topology dependent;
data plane provide no control plane (routing system) uniqueness. however, these service-level identifiers at the data plane provide no
control plane (routing system) uniqueness.
As more services are globally anycasted, and existing anycasted As more services are globally anycasted, and existing anycasted
services realize wider deployment of anycast nodes for a given services realize wider deployment of anycast nodes for a given
service address in order to accommodate growing system loads, the service address in order to accommodate growing system loads, the
difficulty of providing safeguards and controls to better protect difficulty of providing safeguards and controls to better protect
those resources expands. Intuitively, the more widely distributed a those resources expands. Intuitively, the more widely distributed a
given anycasted service address is, the more difficult it becomes for given anycasted service address is, the more difficult it becomes for
network operators to detect operational and security issues that network operators to detect operational and security issues that
affect that service. Some examples of such security and operational affect that service. Some examples of such security and operational
issues include BGP route leaks affecting the anycasted service, rogue issues include BGP route leaks affecting the anycasted service, rogue
anycast nodes appearing for the service, or the emergence of other anycast nodes appearing for the service, or the emergence of other
aberrant behavior in either the routing system, the forward query aberrant behavior in either the routing system, the forward query
datapath, or query response datapath. Diagnosis of the routing datapath, or query response datapath. Diagnosis of the routing
system issues is complicated by the fact that no unique system issues is complicated by the fact that no unique
discriminators exist in the routing system to identify a given local discriminators exist in the routing system to identify a given local
or global anycast node. Furthermore, both datapath and routing or global anycast node. Furthermore, both datapath and routing
system problem identification is compounded by the fact that these system problem identification is compounded by the fact that these
incident types can be topologically-dependent, and only observable incident types can be topologically dependent, and only observable
between a given client-server set. between a given client-server set.
Additionally, while it goes without saying that many anycasted Additionally, while it goes without saying that many anycasted
services strive for exact synchronization across all instances of an services strive for exact synchronization across all instances of an
anycasted service address, if local policies or data plane response anycasted service address, if local policies or data plane response
manipulation techniques were to "influence" responses within a given manipulation techniques were to "influence" responses within a given
region in such a way that those responses are no longer authentic or region in such a way that those responses are no longer authentic or
that they diverge from what other nodes within an anycasted service that they diverge from what other nodes within an anycasted service
were providing, then it should be an absolute necessity that those were providing, then it should be an absolute necessity that those
modified resources only be utilized by service consumers within that modified resources only be utilized by service consumers within that
region or influencer's jurisdiction. region or influencer's jurisdiction.
Mechanisms should exist at both the network and service layer to make Mechanisms should exist at both the network- and service-layer to
it abundantly apparent to operators and users alike whether any of make it abundantly apparent to operators and users alike whether any
the query responses are not authentic. For DNS, DNSSEC [RFC 4033] of the query responses are not authentic. For DNS, DNSSEC [RFC4033]
provides this capability at the service layer with object level provides this capability at the service layer with object-level
integrity, assuming validation is being performed by recursive name integrity, assuming validation is being performed by recursive name
servers, and DNSSEC deployment at the root and top level domain (TLD) servers, and DNSSEC deployment at the root and top-level domain (TLD)
levels is well underway [DNSSEC-DEPLOY]. Furthermore, control plane levels is well underway [DNSSEC-DEPLOY]. Furthermore, control plane
discriminators should exist to enable operators to know toward which discriminators should exist to enable operators to know toward which
of a given set of instances a query is being directed, and to enable of a given set of instances a query is being directed, and to enable
detection and alerting capabilities when this changes. Such detection and alerting capabilities when this changes. Such
discriminators may also be employed to enable anycast node preference discriminators may also be employed to enable anycast node preference
or filtering keys, should local operational policy require it. or filtering keys, should local operational policy require it.
2. Terminology
This document employs much of the following terminology, which was
taken in full from Section 2 of [RFC4786].
Service Address: an IP address associated with a particular
service (e.g., the destination address used by DNS resolvers to
reach a particular authority server).
Anycast: the practice of making a particular Service Address
available in multiple, discrete, autonomous locations, such
that datagrams sent are routed to one of several available
locations.
Anycast Node: an internally-connected collection of hosts and
routers that together provide service for an anycast Service
Address. An Anycast Node might be as simple as a single host
participating in a routing system with adjacent routers, or it
might include a number of hosts connected in some more
elaborate fashion; in either case, to the routing system across
which the service is being anycast, each Anycast Node presents
a unique path to the Service Address. The entire anycast
system for the service consists of two or more separate Anycast
Nodes.
Catchment: in physical geography, an area drained by a river,
also known as a drainage basin. By analogy, as used in this
document, the topological region of a network within which
packets directed at an Anycast Address are routed to one
particular node.
Local-Scope Anycast: reachability information for the anycast
Service Address is propagated through a routing system in such
a way that a particular anycast node is only visible to a
subset of the whole routing system.
Local Node: an Anycast Node providing service using a Local-Scope
Anycast Address.
Global Node: an Anycast Node providing service using a Global-
Scope Anycast Address.
Global-Scope Anycast: reachability information for the anycast
Service Address is propagated through a routing system in such
a way that a particular anycast node is potentially visible to
the whole routing system.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Recommendation for Unique Origin ASNs 3. Recommendation for Unique Origin ASNs
In order to be able to better detect changes to routing information In order to be able to better detect changes to routing information
associated with critical anycasted resources, globally anycasted associated with critical anycasted resources, globally anycasted
services with partitioned origin ASNs SHOULD utilize a unique origin services with partitioned origin ASNs SHOULD utilize a unique origin
ASN per node where possible, if appropriate in their operating ASN per node where possible, if appropriate in their operating
environment and service model. environment and service model.
Discrete origin ASNs per node provide a discriminator in the routing Discrete origin ASNs per node provide a discriminator in the routing
system that would enable detection of leaked or hijacked instances system that would enable detection of leaked or hijacked instances
more quickly, and would also enable operators that so choose to more quickly and would enable operators that so choose to proactively
proactively develop routing policies that express preferences or develop routing policies that express preferences or avoidance for a
avoidance for a given node or set of nodes associated with an given node or set of nodes associated with an anycasted service.
anycasted service. This is particularly useful when it is observed This is particularly useful when it is observed that local policy or
that local policy or known issues exist with the performance or known issues exist with the performance or authenticity of responses
authenticity of responses returned from a specific anycast node, or returned from a specific anycast node, or that enacted policies meant
that enacted policies meant to affect service within a particular to affect service within a particular region are affecting users
region are affecting users outside of that region as a result of a outside of that region as a result of a given anycast catchment
given anycast catchment expanding beyond its intended scope. expanding beyond its intended scope.
Furthermore, inconsistent origin AS announcements associated with Furthermore, inconsistent origin AS announcements associated with
anycasted services for critical infrastructure SHOULD NOT be deemed anycasted services for critical infrastructure SHOULD NOT be deemed
undesirable by routing system reporting functions, but should instead undesirable by routing system reporting functions, but should instead
be embraced in order to better identify the connectedness and be embraced in order to better identify the connectedness and
footprint of a given anycasted service. footprint of a given anycasted service.
While namespace conservation and reasonable use of AS number While namespace conservation and reasonable use of AS number
resources should always be a goal, the introduction of 32-bit ASNs resources should always be a goal, the introduction of 32-bit ASNs
significantly lessens concerns in this space. Globally anycasted significantly lessens concerns in this space. Globally anycasted
resources, in particular those associated with critical resources, in particular, those associated with critical
infrastructure-enabling services such as root and TLD name servers, infrastructure-enabling services such as root and TLD name servers,
SHOULD warrant special consideration with regard to AS number SHOULD warrant special consideration with regard to AS number
allocation practices during policy development by the constituents of allocation practices during policy development by the constituents of
those responsible organizations (e.g., the Regional Internet those responsible organizations (e.g., the Regional Internet
Registries). Additionally, defining precisely what constitutes Registries). Additionally, defining precisely what constitutes
"critical infrastructure services" or "special consideration" (e.g., "critical infrastructure services" or "special consideration" (e.g.,
some small range of 32-bit AS numbers might be provided) is left to some small range of 32-bit AS numbers might be provided) is left to
the constituents of those organizations. Additionally, critical the constituents of those organizations. Additionally, critical
infrastructure employment of 32-bit ASNs for new nodes might well infrastructure employment of 32-bit ASNs for new nodes might well
help to foster more rapid adoption of native 32-bit ASN support by help to foster more rapid adoption of native 32-bit ASN support by
network operators. network operators.
One additional benefit of unique origin AS numbers per anycast node One additional benefit of unique origin AS numbers per anycast node
is that Resource PKI (RPKI) Secure Inter-domain Routing [SIDR] is that Resource Public Key Infrastructure (RPKI) Secure Inter-domain
machinery, and in particular, that of Route Origin Authorizations Routing [SIDR] machinery, and, in particular, that of Route Origin
(ROAs), and routing policies that may be derived based on those ROAs, Authorizations (ROAs), and routing policies that may be derived based
can be employed with per anycast node resolution, rather than relying on those ROAs, can be employed with per-anycast-node resolution,
on a single ROA and common origin AS to cover all instantiations of rather than relying on a single ROA and common origin AS to cover all
an anycasted prefix (possibly hundreds) within the global routing instantiations of an anycasted prefix (possibly hundreds) within the
system. For example, deployments that incorporate partitioned ASN global routing system. For example, in the case of deployments that
anycast models that have a single ASN bound to all nodes but cross incorporate partitioned ASN anycast models that have a single ASN
organizational or political boundaries, a situation may arise where bound to all nodes but crossing organizational or political
nobody would be deemed appropriate to hold the key for the ROA. boundaries, a situation may arise where nobody would be deemed
Additionally, a globally anycasted service within a given IP prefix appropriate to hold the key for the ROA. Additionally, a globally
that shares a common ASN might be taken totally offline because of anycasted service within a given IP prefix that shares a common ASN
the revocation of a ROA for that origin ASN. The RPKI model today might be taken totally offline because of the revocation of an ROA
already inherently accommodates issuance of multiple ROAs with unique for that origin ASN. Today's RPKI model already inherently
origins for a given prefix. accommodates issuance of multiple ROAs with unique origins for a
given prefix.
4. Additional Recommendations for Globally Anycasted Services 4. Additional Recommendations for Globally Anycasted Services
Two additional recommendations for globally anycasted critical Two additional recommendations for globally anycasted critical
infrastructure services are related to publication of information infrastructure services are related to publication of information
associated with a given node's physical location, and which adjacent associated with a given node's physical location, and with which
upstream ASNs an origin AS interconnects with. The former would adjacent upstream ASNs an origin AS interconnects. The former would
allow operators to better define and optimize preferences associated allow operators to better define and optimize preferences associated
with a given node to align with local policy and service with a given node to align with local policy and service
optimizations. The latter would allow expression through policy such optimizations. The latter would allow expression through policy such
as Routing Policy Specification Language [RFC 4012] specified in as Routing Policy Specification Language [RFC4012] specified in
Internet Routing Registries (IRRs) in a manner that illustrates a Internet Routing Registries (IRRs) in a manner that illustrates a
discrete set of upstream ASNs for each anycast node, rather than the discrete set of upstream ASNs for each anycast node, rather than the
current model where all upstream ASNs associated with a common origin current model where all upstream ASNs associated with a common origin
AS may or may not be expressed. This information would provide an AS may or may not be expressed. This information would provide an
additional level of static routing policy or monitoring and detection additional level of static routing policy or monitoring and detection
models by network operators, and perhaps explicit network layer models by network operators and perhaps explicit network-layer source
source address validation in the datapath. address validation in the datapath.
5. Security Considerations 5. Security Considerations
The recommendations made in this memo aim to provide more flexibility The recommendations made in this memo aim to provide more flexibility
for network operators hoping to better monitor and prevent issues for network operators hoping to better monitor and prevent issues
related to globally anycasted critical infrastructure resources. related to globally anycasted critical infrastructure resources.
Anycast itself provides considerable benefit in the face of certain Anycast itself provides considerable benefit in the face of certain
attacks, yet if a given instance of a service can appear at many attacks; yet, if a given instance of a service can appear at many
points in the routing system and legitimate instances are difficult points in the routing system and legitimate instances are difficult
to distinguish from malicious ones, then anycast expands the to distinguish from malicious ones, then anycast expands the
service's attack surface rather than reducing it. service's attack surface rather than reducing it.
The recommendations made in this document are expressed to assist The recommendations made in this document are expressed to assist
with visibility and policy specification capabilities in order to with visibility and policy specification capabilities in order to
improve the availability of critical Internet resources. Use cases improve the availability of critical Internet resources. Use cases,
where the recommendations outlined in this memo may have helped to where the recommendations outlined in this memo may have helped to
more easily detect or scope the impact of a particular incident are more easily detect or scope the impact of a particular incident, are
illustrated in [RENESYS-BLOG]. illustrated in [RENESYS-BLOG].
Furthermore, while application layer protection mechanisms such as Furthermore, while application-layer protection mechanisms such as
DNSSEC provide object level integrity and authentication, they often DNS security extensions (DNSSEC) provide object-level integrity and
do so at the cost of introducing more failure conditions. For authentication, they often do so at the cost of introducing more
example, if a recursive name server is performing DNSSEC validator failure conditions. For example, if a recursive name server is
functions and receives a bogus response to a given query as a result performing DNSSEC validator functions and receives a bogus response
of a man-in-the-middle (MITM) or injected spoofed response packet to a given query as a result of a man-in-the-middle (MITM) or
such as a cache poisoning attempt, the possibility might exist that injected spoofed response packet such as a cache-poisoning attempt,
the response packet is processed by the server and results in some the possibility might exist that the response packet is processed by
temporal or persistent DoS condition on the recursive name server and the server and results in some temporal or persistent DoS condition
for its client set. The unique origin AS mechanism outlined in this on the recursive name server and for its client set. The unique
document provides the capability for network operators to expressly origin AS mechanism outlined in this document provides the capability
avoid anycast node catchments known to regularly elicit bogus for network operators to expressly avoid anycast node catchments
responses, while allowing the anycasted service address to remain known to regularly elicit bogus responses, while allowing the
available otherwise. anycasted service address to remain available otherwise.
6. Deployment Considerations 6. Deployment Considerations
Maintenance of unique ASNs for each node within an anycasted service Maintenance of unique ASNs for each node within an anycasted service
may be challenging for some critical infrastructure service operators may be challenging for some critical infrastructure service operators
initially, but for globally anycasted resources there needs to be initially, but for globally anycasted resources, there needs to be
some type of per-node discriminator in the control plane to enable some type of per-node discriminator in the control plane to enable
detection, remediation, and optimally, preventative controls for detection, remediation, and optimally, preventative controls for
dealing with routing system anomalies that are intensified by the dealing with routing system anomalies that are intensified by the
application of IP anycasting. Additionally, this technique sets the application of IP anycasting. Additionally, this technique sets the
stage to employ RPKI-enabled machinery and more secure and explicit stage to employ RPKI-enabled machinery and more secure and explicit
routing policies, which all network operators should be considering. routing policies, which all network operators should be considering.
The granularity of data publication related to anycast node location The granularity of data publication related to anycast node location
should be left to the devises of each services operator, and the should be left to the devises of each services operator, and the
value of this mechanism in each operators unique environment, but value of this mechanism in each operator's unique environment, but
some reasonable level of detail to enable operators and service some reasonable level of detail to enable operators and service
consumers to make informed decisions that align with their security consumers to make informed decisions that align with their security
and operational objectives as outlined herein should be provided by and operational objectives as outlined herein should be provided by
each critical services operator. each critical services operator.
Adjacent AS information for a given origin AS can be obtained through Adjacent AS information for a given origin AS can already be obtained
careful routing system analysis already when prefixes are advertised through careful routing system analysis when prefixes are advertised
via a given set of AS adjacencies, and therefore should present no via a given set of AS adjacencies, and therefore, should present no
new threat. However, network interconnection and peering policies new threat. However, network interconnection and peering policies
may well present some challenges in this area. For example, if a may well present some challenges in this area. For example, if a
technique such as unique origin AS per node is employed then a single technique such as unique origin AS per node is employed, then a
organizaton may no longer have a single AS for interconnection at single organization may no longer have a single AS for
each location, and interconnection policies should expressly consider interconnection at each location, and interconnection policies should
this. That said, interconnection with networks that provide critical expressly consider this. That said, interconnection with networks
infrastructure services should certainly be given due consideration that provide critical infrastructure services should certainly be
as such by network operators when evaluating interconnection given due consideration as such by network operators when evaluating
strategies. interconnection strategies.
Some root and TLD operators today identify erroneous anycast prefix Today, some root and TLD operators identify erroneous anycast prefix
announcements by detecting prefix announcements with an origin AS announcements by detecting prefix announcements with an origin AS
other than the common origin AS shared via all nodes. This detection other than the common origin AS shared via all nodes. This detection
model would need to be expanded to account for unique origin ASNs per model would need to be expanded to account for unique origin ASNs per
node if a given service operators chooses to employ such a model, and node if a given service operator chooses to employ such a model.
given that AS paths are trivial to manipulate in the current system, Given that AS paths are trivial to manipulate in the current system,
the above technique would only assist in the event of unintentional the above technique would only assist in the event of unintentional
configuration errors that reoriginate the route (e.g., it doesn't configuration errors that reoriginate the route (e.g., it does not
even detect leaks that preserve the initial path elements). In that detect leaks that preserve the initial path elements). In that case,
case, work underway on routing security origin and path validation in work underway on routing security origin and path validation in the
the SIDR working group and beyond should be consulted. SIDR working group and beyond should be consulted.
While local policy based on any BGP attributes, to include AS path While local policy based on any BGP attributes, to include AS path
information, can influence policy within a local administrative information, can influence policy within a local administrative
domain and possibly downstream, there exists a possibly that upstream domain and possibly downstream, there exists a possibility that
nodes continue to use a route deemed undesirable by the local admin upstream nodes continue to use a route deemed undesirable by the
once data packets reach that network. Network operators must local administrator once data packets reach that network. Network
understand the implications of this property in their operating operators must understand the implications of this property in their
environment, as it is inherent in all Interent routing. operating environment, as it is inherent in all Internet routing.
Finally, anycast node presence at exchange points that employ route Finally, anycast node presence at exchange points that employ route
servers may make enumeration of adjacent ASNs for a given node servers may make enumeration of adjacent ASNs for a given node
challenging. While this is understood, service operators should make challenging. While this is understood, service operators should make
every effort to enumerate the set of adjacent ASNs associated with a every effort to enumerate the set of adjacent ASNs associated with a
given anycast node's origin AS. Without express understanding of given anycast node's origin AS. Without express understanding of
legitimate AS interconnection and authorized origin AS information, legitimate AS interconnection and authorized origin AS information,
more secure routing is difficult to achieve. more secure routing is difficult to achieve.
7. Acknowledgements 7. Acknowledgements
Thanks to David Conrad, Steve Kent, Mark Kosters, Andrei Robachevsky, Thanks to David Conrad, Steve Kent, Mark Kosters, Andrei Robachevsky,
Paul Vixie, Brad Verd, Andrew Herrmann, Gaurab Raj Upadhaya, Joe Paul Vixie, Brad Verd, Andrew Herrmann, Gaurab Raj Upadhaya, Joe
Abley, Benson Schliesser, Shane Amante, Hugo Salgado, and Randy Bush Abley, Benson Schliesser, Shane Amante, Hugo Salgado, and Randy Bush
for review and comments on this concept. for review and comments on this concept.
8. IANA Considerations 8. IANA Considerations
This document requires no direct IANA actions, although it does This document requires no direct IANA actions, although it does
provide general guidance to number resource allocation and policy provide general guidance to number resource allocation and policy
development organizations, and in particular Regional Internet development organizations, and, in particular, Regional Internet
Registries, regarding allocation of AS numbers for globally anycasted Registries, regarding allocation of AS numbers for globally anycasted
services. services.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 4786] Abley, J., and Lindqvist, K., "Operation of Anycast [RFC4786] Abley, J. and K. Lindqvist, "Operation of Anycast
Services", RFC 4786, BCP 126, December 2006. Services", BCP 126, RFC 4786, December 2006.
9.2. Informative References 9.2. Informative References
[RFC 4012] Blunk, et al., "Routing Policy Specification Language [DNSSEC-DEPLOY]
next generation (RPSLng)", RFC 4012, March 2005. "Root DNSSEC", <http://www.root-dnssec.org/>
[RFC 4033] Arends, et al., "DNS Security Introduction and [RENESYS-BLOG]
Requirements", RFC 4033, March 2005. Zmijewski, E., "Accidentally Importing Censorship",
Renesys Blog, March 30, 2010.
<http://www.renesys.com/blog/2010/03/
fouling-the-global-nest.shtml>
[DNSSEC-DEPLOY] "Root DNSSEC", <http://www.root-dnssec.org/> [RFC4012] Blunk, L., Damas, J., Parent, F., and A. Robachevsky,
"Routing Policy Specification Language next generation
(RPSLng)", RFC 4012, March 2005.
[HNAME] ISC, "Which F-root node am I using?" [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
<http://www.isc.org/community/f-root/which_node> Rose, "DNS Security Introduction and Requirements", RFC
4033, March 2005.
[RENESYS-BLOG] Zmijewski, E., "Accidentally Importing Censorship", [RFC4892] Woolf, S. and D. Conrad, "Requirements for a Mechanism
Renesys Blog, March 30, 2010. Identifying a Name Server Instance", RFC 4892, June 2007.
<http://www.renesys.com/blog/2010/03/fouling-the-global-nest.shtml>
[SIDR] Lepinski, M., Kent, S., "An Infrastructure to Support Secure [RFC5001] Austein, R., "DNS Name Server Identifier (NSID) Option",
Internet Routing", October 2009, Internet-Draft, "Work in RFC 5001, August 2007.
Progress".
10. Authors' Addresses [SIDR] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", Work in Progress, May 2011.
Authors' Addresses
Danny McPherson Danny McPherson
Verisign, Inc. Verisign, Inc.
21345 Ridgetop Circle 21345 Ridgetop Circle
Dulles, VA USA 20166 Dulles, VA USA 20166
Phone: +1 703.948.3200 Phone: +1 703.948.3200
Email: dmcpherson@verisign.com EMail: dmcpherson@verisign.com
Ryan Donnelly Ryan Donnelly
Verisign, Inc. Verisign, Inc.
21345 Ridgetop Circle 21345 Ridgetop Circle
Dulles, VA USA 20166 Dulles, VA USA 20166
Phone: +1 703.948.3200 Phone: +1 703.948.3200
Email: rdonnelly@verisign.com EMail: rdonnelly@verisign.com
Frank Scalzo Frank Scalzo
Verisign, Inc. Verisign, Inc.
21345 Ridgetop Circle 21345 Ridgetop Circle
Dulles, VA USA 20166 Dulles, VA USA 20166
Phone: +1 703.948.3200 Phone: +1 703.948.3200
Email: fscalzo@verisign.com EMail: fscalzo@verisign.com
Copyright Statement
Copyright (C) (2011) The IETF Trust and the persons
identified as the document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document.
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