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requirements-06
Revised draft, attached below, has been sent in and should appear in
the usual places in due course. Apologies for the delay in making these
changes.
RFC 2629 source diff follows.
[jabley@snowfall]% cvs diff -u -r 1.5 -r 1.6
draft-ietf-multi6-multihoming-requirements.xml
Index: draft-ietf-multi6-multihoming-requirements.xml
===================================================================
RCS file:
/home/cvs/doc/ietf/draft-ietf-multi6-multihoming-requirements.xml,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -r1.5 -r1.6
--- draft-ietf-multi6-multihoming-requirements.xml 16 Apr 2003
13:40:47 -0000 1.5
+++ draft-ietf-multi6-multihoming-requirements.xml 16 May 2003
17:19:43 -0000 1.6
@@ -5,7 +5,7 @@
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
-<rfc ipr="full2026"
docName="draft-ietf-multi6-multihoming-requirements-05">
+<rfc ipr="full2026"
docName="draft-ietf-multi6-multihoming-requirements-06">
<front>
<title abbrev="IPv6 Site-Multihoming Goals">
Goals for IPv6 Site-Multihoming Architectures
@@ -15,13 +15,13 @@
<organization abbrev="ISC">Internet Software
Consortium</organization>
<address>
<postal>
- <street>10805 Old River Road</street>
- <country>Canada</country>
- <code>N0L 1R0</code>
- <region>ON</region>
- <city>Komoka</city>
+ <street>950 Charter Street</street>
+ <country>USA</country>
+ <code>94063</code>
+ <region>CA</region>
+ <city>Redwood City</city>
</postal>
- <phone>+1 519 641 4368</phone>
+ <phone>+1 650 423 1317</phone>
<email>jabley@isc.org</email>
</address>
</author>
@@ -43,7 +43,7 @@
<date month="April" year="2003" />
<area>Operations and Management</area>
- <workgroup>multi6</workgroup>
+ <workgroup>Network Working Group</workgroup>
<abstract>
<t>Site-multihoming, i.e. connecting to more than one IP service
@@ -65,16 +65,15 @@
<t>However,
it appears that this hierarchy is being supplanted by a dense
mesh
- of interconnections <xref target="refs.Huston" />. Additionally,
+ of interconnections <xref target="refs.RFC3221" />.
Additionally,
there has been an enormous growth in the number of multihomed
sites. For purposes of redundancy and load-sharing, the
- multihomed address blocks, which are almost always a longer
prefix
- than the provider aggregate, are announced along with the larger,
- covering
- aggregate originated by the provider. This contributes to the
- rapidly-increasing size
- of the global routing table. This explosion places significant
- stress on the inter-provider routing system.</t>
+ multihomed address blocks are introduced into the global table
+ even if they are covered by a provider aggregate.
+ This contributes to the
+ rapidly-increasing size of both
+ the global routing table and the turbulence exhibited within
+ it, and places stress on the inter-provider routing system.</t>
<t>Continued growth of both the Internet and the practice of
site-multihoming will seriously exacerbate this stress. The
@@ -123,7 +122,8 @@
circuits ordered from different suppliers and connecting
a site to independent transit providers may share a single
conduit from the street into a building; in this case
- backhoe-fade of both circuits may be experienced due to a
+ physical disruption (sometimes referred to as
+ "backhoe-fade") of both circuits may be experienced due to a
single incident in the street. The two circuits are said
to "share fate".</t>
@@ -146,7 +146,7 @@
<section anchor="loadshare" title="Load Sharing">
<t>By multihoming, a site should be able to
distribute both inbound and outbound traffic between multiple
- transit providers. This requirement is for concurrent
+ transit providers. This goal is for concurrent
use of the multiple transit providers, not just the usage
of one provider over one interval of time and another
provider
over a different interval.</t>
@@ -184,9 +184,12 @@
<t>As any proposed multihoming solution must be deployed in
real
networks with real customers, simplicity is paramount. The
current multihoming solution is quite
- straightforward to deploy and maintain. A new IPv6
multihoming
- proposal should not be substantially more complex to deploy
and
- operate than current IPv4 multihoming practices.</t>
+ straightforward to deploy and maintain.</t>
+
+ <t>A new IPv6 multihoming
+ solution should not be substantially more complex to deploy
and
+ operate (for multihomed sites or for the rest of the
Internet)
+ than current IPv4 multihoming practices.</t>
</section>
<section anchor="transportSurvivability" title="Transport-Layer
@@ -213,13 +216,14 @@
<t>Multi-homing solutions either should be compatible with the
observed dynamics of the current DNS system, or the solutions
should demonstrate that the modified name resolution
- system required to support them are readily deployable.</t>
+ system required to support them is readily deployable.</t>
</section>
<section anchor="antiSpoofing" title="Packet Filtering">
<t>Multihoming solutions should not preclude filtering packets
with forged or otherwise inappropriate source IP addresses
- at the administrative boundary of the multihomed site.</t>
+ at the administrative boundary of the multihomed site, or
+ at the administrative boundaries of any site in the
Internet.</t>
</section>
</section>
@@ -231,7 +235,7 @@
is a concern both because of the hardware requirements
it imposes and also because of the impact on the stability
of the routing system. This issue is discussed in great
- detail in <xref target="refs.Huston" />.</t>
+ detail in <xref target="refs.RFC3221" />.</t>
<t>A new IPv6 multihoming architecture should scale
to accommodate orders of magnitude more multihomed sites
@@ -240,7 +244,7 @@
</section>
<section anchor="routerImpact" title="Impact on Routers">
- <t>The solution may require changes to IPv6 router
implementations,
+ <t>The solutions may require changes to IPv6 router
implementations,
but these changes should be either minor, or in the form of
logically
separate functions added to existing functions.</t>
@@ -253,7 +257,7 @@
<t>The solution should not destroy IPv6 connectivity for a
legacy host
implementing RFC 3513 <xref target="refs.RFC3513" />,
RFC 2460 <xref target="refs.RFC2460" />,
- RFC 2553 <xref target="refs.RFC2553" /> and other basic IPv6
+ RFC 3493 <xref target="refs.RFC3493" /> and other basic IPv6
specifications current in April 2003. That is to say, if a
host
can work
in a single-homed site, it should still be able to work in a
@@ -274,7 +278,7 @@
cannot benefit from multihoming.</t>
<t>The multihoming solution may allow host or application
- changes if that would enhance session survivability.</t>
+ changes if that would enhance transport-layer
survivability.</t>
</section>
<section anchor="hostrouter" title="Interaction between Hosts and
@@ -285,7 +289,7 @@
</section>
<section anchor="operations" title="Operations and Management">
- <t>It should be posssible for staff responsible for the
operation
+ <t>It should be possible for staff responsible for the
operation
of a site to monitor and configure the site's
multihoming system.</t>
</section>
@@ -296,6 +300,11 @@
and its transit providers, but should not require cooperation
(relating specifically to the multihomed site)
directly between the transit providers.</t>
+
+ <t>The impact of any inter-site cooperation that might be
+ required to facilitate the multihoming solution should be
+ examined and assessed from the point of view of operational
+ practicality.</t>
</section>
<section anchor="multipleSolutions" title="Multiple Solutions">
@@ -381,23 +390,6 @@
<seriesInfo name="RFC" value="3513" />
</reference>
- <reference anchor="refs.RFC2374">
- <front>
- <title>An IPv6 Aggregatable Global Unicast Address
Format</title>
- <author initials="R." surname="Hinden">
- <organization>Nokia</organization>
- </author>
- <author initials="M." surname="O'Dell">
- <organization>UUNET</organization>
- </author>
- <author initials="S." surname="Deering">
- <organization>Cisco</organization>
- </author>
- <date month="July" year="1998" />
- </front>
- <seriesInfo name="RFC" value="2374" />
- </reference>
-
<reference anchor="refs.RFC2460">
<front>
<title>Internet Protocol, Version 6 (IPv6)
Specification</title>
@@ -412,34 +404,35 @@
<seriesInfo name="RFC" value="2460" />
</reference>
- <reference anchor="refs.RFC2553">
+ <reference anchor="refs.RFC3493">
<front>
<title>Basic Socket Interface Extensions for IPv6</title>
<author initials="R." surname="Gilligan">
- <organization>FreeGate</organization>
+ <organization>Intransa, Inc.</organization>
</author>
<author initials="S." surname="Thomson">
- <organization>Bellcore</organization>
+ <organization>Cisco Systems</organization>
</author>
<author initials="J." surname="Bound">
- <organization>Compaq</organization>
+ <organization>Hewlett-Packard Company</organization>
</author>
- <author initials="W." surname="Stevens">
- <organization>Consultant</organization>
+ <author initials="J." surname="McCann">
+ <organization>Hewlett-Packard Company</organization>
</author>
- <date month="March" year="1999" />
+ <date month="February" year="2003" />
</front>
- <seriesInfo name="RFC" value="2553" />
+ <seriesInfo name="RFC" value="3493" />
</reference>
- <reference anchor="refs.Huston">
+ <reference anchor="refs.RFC3221">
<front>
- <title>Analyzing the Internet's BGP Routing Table</title>
+ <title>Commentary on Inter-Domain Routing in the
Internet</title>
<author initials="G." surname="Huston">
<organization>Telstra</organization>
</author>
- <date month="January" year="2001" />
+ <date month="December" year="2001" />
</front>
+ <seriesInfo name="RFC" value="3221" />
</reference>
</references>
</back>
Network Working Group J. Abley
Internet-Draft ISC
Expires: September 30, 2003 B. Black
Layer8 Networks
V. Gill
AOL Time Warner
April 2003
Goals for IPv6 Site-Multihoming Architectures
draft-ietf-multi6-multihoming-requirements-06
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task 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
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 http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 30, 2003.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
Site-multihoming, i.e. connecting to more than one IP service
provider, is an essential component of service for many sites which
are part of the Internet.
This document outlines a set of goals for proposed new IPv6
site-multihoming architectures.
1. Introduction
Abley, et al. Expires September 30, 2003 [Page 1]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
Current IPv4 site-multihoming practices have been added on to the
CIDR architecture [1], which assumes that routing table entries can
be aggregated based upon a hierarchy of customers and service
providers.
However, it appears that this hierarchy is being supplanted by a
dense mesh of interconnections [6]. Additionally, there has been an
enormous growth in the number of multihomed sites. For purposes of
redundancy and load-sharing, the multihomed address blocks are
introduced into the global table even if they are covered by a
provider aggregate. This contributes to the rapidly-increasing size
of both the global routing table and the turbulence exhibited within
it, and places stress on the inter-provider routing system.
Continued growth of both the Internet and the practice of
site-multihoming will seriously exacerbate this stress. The
site-multihoming architecture for IPv6 should allow the routing
system to scale more pleasantly.
2. Terminology
A "site" is an entity autonomously operating a network using IP and,
in particular, determining the addressing plan and routing policy for
that network. This definition is intended to be equivalent to
"enterprise" as defined in [2].
A "transit provider" operates a site which directly provides
connectivity to the Internet to one or more external sites. The
connectivity provided extends beyond the transit provider's own site.
A transit provider's site is directly connected to the sites for
which it provides transit.
A "multihomed" site is one with more than one transit provider.
"Site-multihoming" is the practice of arranging a site to be
multihomed.
The term "re-homing" denotes a transition of a site between two
states of connectedness, due to a change in the connectivity between
the site and its transit providers' sites.
3. Multihoming Goals
3.1 Capabilities of IPv4 Multihoming
The following capabilities of current IPv4 multihoming practices
should be supported by an IPv6 multihoming architecture.
Abley, et al. Expires September 30, 2003 [Page 2]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
3.1.1 Redundancy
By multihoming, a site should be able to insulate itself from certain
failure modes within one or more transit providers, as well as
failures in the network providing interconnection among one or more
transit providers.
Infrastructural commonalities below the IP layer may result in
connectivity which is apparently diverse sharing single points of
failure. For example, two separate DS3 circuits ordered from
different suppliers and connecting a site to independent transit
providers may share a single conduit from the street into a building;
in this case physical disruption (sometimes referred to as
"backhoe-fade") of both circuits may be experienced due to a single
incident in the street. The two circuits are said to "share fate".
The multihoming architecture should accommodate (in the general case,
issues of shared fate notwithstanding) continuity of connectivity
during the following failures:
o Physical failure, such as a fiber cut, or router failure,
o Logical link failure, such as a misbehaving router interface,
o Routing protocol failure, such as a BGP peer reset,
o Transit provider failure, such as a backbone-wide IGP failure, and
o Exchange failure, such as a BGP reset on an inter-provider
peering.
3.1.2 Load Sharing
By multihoming, a site should be able to distribute both inbound and
outbound traffic between multiple transit providers. This goal is for
concurrent use of the multiple transit providers, not just the usage
of one provider over one interval of time and another provider over a
different interval.
3.1.3 Performance
By multihoming, a site should be able to protect itself from
performance difficulties directly between the site's transit
providers.
For example, suppose site E obtains transit from transit providers T1
and T2, and there is long-term congestion between T1 and T2. The
Abley, et al. Expires September 30, 2003 [Page 3]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
multihoming architecture should allow E to ensure that in normal
operation none of its traffic is carried over the congested
interconnection T1-T2. The process by which this is achieved should
be a manual one.
A multihomed site should be able to distribute inbound traffic from
particular multiple transit providers according to the particular
address range within their site which is sourcing or sinking the
traffic.
3.1.4 Policy
A customer may choose to multihome for a variety of policy reasons
beyond technical scope (e.g. cost, acceptable use conditions, etc.)
For example, customer C homed to ISP A may wish to shift traffic of a
certain class or application, NNTP, for example, to ISP B as matter
of policy. A new IPv6 multihoming proposal should provide support
for site-multihoming for external policy reasons.
3.1.5 Simplicity
As any proposed multihoming solution must be deployed in real
networks with real customers, simplicity is paramount. The current
multihoming solution is quite straightforward to deploy and maintain.
A new IPv6 multihoming solution should not be substantially more
complex to deploy and operate (for multihomed sites or for the rest
of the Internet) than current IPv4 multihoming practices.
3.1.6 Transport-Layer Survivability
Multihoming solutions should provide re-homing transparency for
transport-layer sessions; i.e. exchange of data between devices on
the multihomed site and devices elsewhere on the Internet may proceed
with no greater interruption than that associated with the transient
packet loss during the re-homing event.
New transport-layer sessions should be able to be created following a
re-homing event.
Transport-layer sessions include those involving transport-layer
protocols such as TCP, UDP and SCTP over IP. Applications which
communicate over raw IP and other network-layer protocols may also
enjoy re-homing transparency.
3.1.7 Impact on DNS
Multi-homing solutions either should be compatible with the observed
Abley, et al. Expires September 30, 2003 [Page 4]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
dynamics of the current DNS system, or the solutions should
demonstrate that the modified name resolution system required to
support them is readily deployable.
3.1.8 Packet Filtering
Multihoming solutions should not preclude filtering packets with
forged or otherwise inappropriate source IP addresses at the
administrative boundary of the multihomed site, or at the
administrative boundaries of any site in the Internet.
3.2 Additional Requirements
3.2.1 Scalability
Current IPV4 multihoming practices contribute to the significant
growth currently observed in the state held in the global
inter-provider routing system; this is a concern both because of the
hardware requirements it imposes and also because of the impact on
the stability of the routing system. This issue is discussed in great
detail in [6].
A new IPv6 multihoming architecture should scale to accommodate
orders of magnitude more multihomed sites without imposing
unreasonable requirements on the routing system.
3.2.2 Impact on Routers
The solutions may require changes to IPv6 router implementations, but
these changes should be either minor, or in the form of logically
separate functions added to existing functions.
Such changes should not prevent normal single-homed operation, and
routers implementing these changes should be able to interoperate
fully with hosts and routers not implementing them.
3.2.3 Impact on Hosts
The solution should not destroy IPv6 connectivity for a legacy host
implementing RFC 3513 [3], RFC 2460 [4], RFC 3493 [5] and other basic
IPv6 specifications current in April 2003. That is to say, if a host
can work in a single-homed site, it should still be able to work in a
multihomed site, even if it cannot benefit from site-multihoming.
It would be compatible with this goal for such a host to lose
connectivity if a site lost connectivity to one transit provider,
despite the fact that other transit provider connections were still
operational.
Abley, et al. Expires September 30, 2003 [Page 5]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
If the solution requires changes to the host stack, these changes
should be either minor, or in the form of logically separate
functions added to existing functions.
If the solution requires changes to the socket API and/or the
transport layer, it should be possible to retain the original socket
API and transport protocols in parallel, even if they cannot benefit
from multihoming.
The multihoming solution may allow host or application changes if
that would enhance transport-layer survivability.
3.2.4 Interaction between Hosts and the Routing System
The solution may involve interaction between a site's hosts and its
routing system; such an interaction should be simple, scaleable and
securable.
3.2.5 Operations and Management
It should be possible for staff responsible for the operation of a
site to monitor and configure the site's multihoming system.
3.2.6 Cooperation between Transit Providers
A multihoming strategy may require cooperation between a site and its
transit providers, but should not require cooperation (relating
specifically to the multihomed site) directly between the transit
providers.
The impact of any inter-site cooperation that might be required to
facilitate the multihoming solution should be examined and assessed
from the point of view of operational practicality.
3.2.7 Multiple Solutions
There may be more than one approach to multihoming, provided all
approaches are orthogonal (i.e. each approach addresses a distinct
segment or category within the site multihoming problem). Multiple
solutions will incur a greater management overhead, however, and the
adopted solutions should attempt to cover as many multihoming
scenarios and goals as possible.
4. Security Considerations
A multihomed site should not be more vulnerable to security breaches
than a traditionally IPv4-multihomed site.
Abley, et al. Expires September 30, 2003 [Page 6]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
Any changes to routing practices made to accommodate multihomed sites
should not cause non-multihomed sites to become more vulnerable to
security breaches.
Normative References
[1] Fuller, V., Li, T., Yu, J. and K. Varadhan, "Classless
Inter-Domain Routing (CIDR): an Address Assignment and
Aggregation Strategy", RFC 1519, September 1993.
[2] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G. and E.
Lear, "Address Allocation for Private Internets", RFC 1918,
February 1996.
[3] Hinden, R. and S. Deering, "Internet Protocol Version 6 (IPv6)
Addressing Architecture", RFC 3513, April 2003.
[4] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6)
Specification", RFC 2460, December 1998.
[5] Gilligan, R., Thomson, S., Bound, J. and J. McCann, "Basic
Socket Interface Extensions for IPv6", RFC 3493, February 2003.
[6] Huston, G., "Commentary on Inter-Domain Routing in the
Internet", RFC 3221, December 2001.
Authors' Addresses
Joe Abley
Internet Software Consortium
950 Charter Street
Redwood City, CA 94063
USA
Phone: +1 650 423 1317
EMail: jabley@isc.org
Benjamin Black
Layer8 Networks
EMail: ben@layer8.net
Abley, et al. Expires September 30, 2003 [Page 7]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
Vijay Gill
AOL Time Warner
EMail: vijaygill9@aol.com
Abley, et al. Expires September 30, 2003 [Page 8]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
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Abley, et al. Expires September 30, 2003 [Page 9]
Internet-Draft IPv6 Site-Multihoming Goals April 2003
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
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Abley, et al. Expires September 30, 2003 [Page 10]