Architectural Considerations of IP Anycast
RFC 7094
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RFC - Informational
(January 2014; No errata)
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Last updated |
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2014-01-16
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IAB
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plain text
pdf
html
bibtex
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IAB state
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Published RFC
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Consensus Boilerplate |
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Yes
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RFC Editor Note |
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(None)
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Internet Architecture Board (IAB) D. McPherson
Request for Comments: 7094 Verisign, Inc.
Category: Informational D. Oran
ISSN: 2070-1721 Cisco Systems
D. Thaler
Microsoft Corporation
E. Osterweil
Verisign, Inc.
January 2014
Architectural Considerations of IP Anycast
Abstract
This memo discusses architectural implications of IP anycast and
provides some historical analysis of anycast use by various IETF
protocols.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Architecture Board (IAB)
and represents information that the IAB has deemed valuable to
provide for permanent record. It represents the consensus of the
Internet Architecture Board (IAB). Documents approved for
publication by the IAB are not a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7094.
Copyright Notice
Copyright (c) 2014 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.
McPherson, et al. Informational [Page 1]
RFC 7094 Arch Considerations of IP Anycast January 2014
Table of Contents
1. Overview ........................................................2
2. Background ......................................................3
2.1. Anycast History ............................................3
2.2. Anycast in IPv6 ............................................6
2.3. DNS Anycast ................................................6
2.4. BCP 126 on Operation of Anycast Services ...................8
3. Principles ......................................................8
3.1. Layering and Resiliency ....................................8
3.2. Anycast Addresses as Destinations ..........................9
3.3. Anycast Addresses as Sources ..............................10
3.4. Service Discovery .........................................10
4. Analysis .......................................................11
4.1. Regarding Widespread Anycast Use ..........................11
4.2. Transport Implications ....................................11
4.3. Stateful Firewalls, Middleboxes, and Anycast ..............12
4.4. Security Considerations ...................................12
4.5. Deployment Considerations .................................15
5. Conclusions ....................................................16
6. Acknowledgements ...............................................16
7. Informative References .........................................16
Appendix A. IAB Members at the Time of Approval ...................21
1. Overview
IP anycast is a technique with a long legacy and interesting
engineering challenges. However, at its core, it is a relatively
simple concept. As described in BCP 126 [RFC4786], the general form
of IP anycast is 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.
IP anycast is used for at least one critical Internet service: that
of the Domain Name System [RFC1035] root servers. By late 2007, at
least 10 of the 13 root name servers were already using IP anycast
[RSSAC29]. Use of IP anycast is growing for other applications as
well. It has been deployed for over a decade for DNS resolution
services and is currently used by several DNS Top Level Domain (TLD)
operators. IP anycast is also used for other services in operational
environments, including Network Time Protocol (NTP) [RFC5905]
services.
Anycast addresses are syntactically indistinguishable from unicast
addresses. Anycast addressing is equivalent to that of unicast in
multiple locations. Destination-based routing does best-effort
delivery of a packet to one interface among the set of interfaces
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