wdiff draft-templin-ranger-02.txt draft-templin-ranger-04.txt

Network Working Group F. Templin, Ed.
Internet-Draft Boeing Phantom Works
Intended status: Informational October 23, November 17, 2008
Expires: April 26, May 21, 2009

Routing and Addressing in Next-Generation EnteRprises (RANGER)
draft-templin-ranger-02.txt
draft-templin-ranger-04.txt

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Abstract

Enterprise networks will require support for both Internet protocol
versions (IPv4 and IPv6) for an indeterminant period; perhaps even
indefinitely. This is particularly true for existing enterprise
networks that must introduce IPv6 without disruption of IPv4
services, but the same principles apply also to even for clean-slate
deployments in new enterprises. Next-generation enterprises
therefore require an architected solution for coordination of their
internal routing and addressing plans for both IPv6 and IPv4. The
RANGER architecture addresses these requirements.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 4
3. The RANGER Architecture . . . . . . . . . . . . . . . . . . . 5 6
3.1. The Enterprise-within-Enterprise Framework . . . . . . . . 5 6
3.2. Virtual Enterprise Traversal (VET) . . . . . . . . . . . . 8
3.3. Support for IPv4 Services . . . . . . . . . . . . . . . . 10 12
3.4. Subnetwork Encapsulation and Adaptation Layer (SEAL) . . . 12 13
3.5. Mobility Management . . . . . . . . . . . . . . . . . . . 12 14
4. Initiatives Related to RANGER/VET/SEAL . . . . . . . . . . . . 13 14
4.1. 6over4 and ISATAP . . . . . . . . . . . . . . . . . . . . 13 14
4.2. The Locator Identifier Split Protocol (LISP) . . . . . . . 13 14
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 15
7. Related Work . . . . . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
9. 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. 16
8.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. 16
8.2. Informative References . . . . . . . . . . . . . . . . . . 15 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17 18
Intellectual Property and Copyright Statements . . . . . . . . . . 18 19

1. Introduction

RANGER is a scalable architecture for routing and addressing in next-
generation enterprise networks that may either comprise a single
interior IPv4 addressing domain or contain many multiple disjoint interior
IPv4 addressing domains. Each of these domains may coordinate their
own internal addressing plans independently of one another such that
limited-scope addresses (e.g., [RFC1918] private-use IPv4 addresses)
may be reused with impunity to provide unlimited scaling through
spatial reuse. These disjoint domains Each addressing domain therefore appear appears as
enterprises an
enterprise unto themselves, itself, such that a model of recursively nested
"enterprises-within-enterprises" is enabled. Logical or physical
partitioning of an enterprise into multiple sites is also possible
and beneficial in many scenarios.

Without an architected approach, routing and addressing within such a
framework would be fragmented due to limited-scope address/prefix
reuse between disjoint addressing domains. However, the entire enterprise
can be unified via a virtual overlay architecture mainfested by
automatic tunneling over disjoint domains interconnected via border
routers.

RANGER provides an architecture for operation of virtual overlay
networks within a diverse range of enterprise network scenarios, as
outlined in the following sections. While RANGER discusses the
specific instance of IPv6 as a virtual overlay for connecting
disjoint over or IPv4 domains, networks,
it is important to note that the same architectural principles apply
to any combination of IP IP* within IP* virtual
overlays over disjoint IP addressing spaces. overlays.

The RANGER architecture uses many mechanisms already documented or
proposed in the IRTF and IETF. Technical details of the composite
technologies that make up the architecture are found in the Virtual
Enterprise Traversal (VET) specification [I-D.templin-autoconf-dhcp].

The RANGER architectural principles can be either directly or
indirectly traced to the deliberations of the ROAD group in January
1992 [RFC1380], and also to still earlier works including NIMROD
[RFC1753], the Catenet model for internetworking [CATENET][IEN48]
[RFC2775], and many others. [RFC1955] [RFC1955] captures the high-
level architectural aspects of the ROAD group deliberations in a "New
Scheme for Internet Routing and Addressing [ENCAPS] for IPNG".

2. Terminology

commons
a routing region within an enterprise that provides a subnetwork
for cooperative peering between the border routers of diverse
organizations that may have competing interests. A prime example
of a commons is the Default Free Zone (DFZ) of the global
Internet.

enterprise
the same as defined in [RFC4852], where the enterprise deploys a
unified IPv4 routing and addressing plan within the commons, but
may internally contain many disjoint interior addressing domains and/or
organizational groupings that can be considered as enterprises/sites enterprises
unto themselves. An enterprise therefore need not be "one big
happy family", but instead provides a commons for the cooperative
interconnection of diverse organizations that may have competing
interests (e.g., such as the case within the global Internet
default free zone).

Enterprise networks are typically associated with large
corporations or academic campuses, however the RANGER
architectural principles apply to any network that has some degree
of cooperative active management. This definition can therefore
be extended to home networks, small office networks, a wide
variety of mobile ad-hoc networks (MANETs), and even to the global
Internet itself.

site
a logical and/or physical grouping of interfaces within a unified
IPv4 addressing region of an enterprise, where the topology of the
site may be less than or equal to an
enterprise in scope. is a proper subset of the topology of the enterprise. A site
may contain many interior
enterprises/sites, sites, which may themselves contain many
interior
enterprises/sites sites in a recursive fashion. At the lowest level of
decomposition, a singleton Border Router can be considered as an
enterprise/site unto itself.

enterprise/site

Throughout the remainder of this document, the term "enterprise" is used to collectively refer
refers to either enterprise or site, i.e., the RANGER principles
apply equally to enterprises and sites of any size or shape. At
the lowest level of decomposition, a singleton Border Router can
be considered as an enterprise unto itself.

Border Router (BR)
an IPv6/IPv4 dual-stack node at the edge of an enterprise and that
is also configured as an IPv6 router in an overlay network. BRs
connect their directly-attached IPv6 networks to the overlay
network, and connect to other IPv6 networks via IPv6-in-IPv4
tunneling across the commons to other BRs.

Border Gateway (BG)
a BR that also connects the enterprise to provider networks and/or
to the global Internet. BGs are typically configured as default
IPv6 routers, and provide forwarding services for accessing IPv6
networks not reachable via a BR within the commons.

overlay network
a virtual network manifested by IPv6 routing and addressing over
virtual links formed through automatic IPv6-in-IPv4 tunneling. An
IPv6 overlay network may span many underlying IPv4 enterprises/
sites. enterprises.

6over4
Transmission of IPv6 over IPv4 Domains without Explicit Tunnels
[RFC2529]; functional specifications and operational practices for
automatic tunneling of unicast/multicast IPv6 packets over
multicast-capable IPv4 enterprises/sites. enterprises.

ISATAP
Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)
[RFC5214]; functional specifications and operational practices for
automatic tunneling of unicast IPv6 packets over unicast-only IPv4
enterprises/sites.
enterprises.

VET
Virtual Enterprise Traversal (VET) [I-D.templin-autoconf-dhcp];
functional specifications and operational practices that provide a
functional superset of 6over4 and ISATAP. In addition to both
unicast and multicast tunneling, VET also supports address/prefix
autoconfiguration as well as extra additional encapsulations such as
IPSec, SEAL, LISP, etc.

SEAL
Subnetwork Encapsulation and Adaptation Layer (SEAL)
[I-D.templin-seal]; a functional specification for robust and
authenticated path MTU assurance over IPv6-in-IPv4 tunnels. Also
provides authentication for other ICMP error messages, and adapts
to subnetworks configured over links with diverse link characteristics.

3. The RANGER Architecture

The RANGER architecture enables scalable IPv6 routing and addressing
in next-generation enterprise networks, while sustaining support for
legacy IPv4 networks and services. Key to this approach is a
framework that accommodates interconnection of diverse organizations
within the enterprise with a mutual spirit of cooperation, but with
the potential for competing interests. The following sections
outline the RANGER architecture within the context of anticipated use
cases:

3.1. The Enterprise-within-Enterprise Framework

Enterprise networks traditionally distribute routing information via
Interior Gateway Protocols (IGPs) such as Open Shortest Path First
(OSPF), while large enterprises may even use an Exterior Gateway
Protocol (EGP) internally in place of an IGP. In particular, it is
becoming increasingly commonplace for large enterprises to use the
Border Gateway Protocol (BGP) internally and independently from the
BGP instance that maintains the routing information base within the
global Internet Default Free Zone (DFZ).

As such, large enterprises may run an internal instance of BGP across
many internal Autonomous Systems (ASs). Such a large enterprise can
therefore appear as an Internet unto itself, albeit with default
routes leading to the true global Internet. Additionally, each
internal AS within such an enterprise may itself run BGP internally
in place of an IGP, and can therefore also appear as an independent
enterprise unto itself. This enterprise-within-enterprise (or,
"site-within-site") framework
can be extended in an hierarchical fashion as broadly and as deeply
as desired to acheive scaling factors as well as organizational
and/or functional compartmentalization, as shown in Figure 1.

,---------------.
,-' Global `-. <--------+
( IPv6/IPv4 ) ,----|-----.
`-. Internet ,-' ( Enterprises)
`+--+..+--+ ...+--+ ( E2 thru EN )
_.-|R1|--|R2+----|Rn|-._ `.---------/
_.---'' +--+ +--+ ...+--+ -.
,--'' ,---. `---.
,-' X5 X6 .---.. `-.
,' ,.X1-.. / \ ,' `. `.
,' ,' `. .' E1.2 '. X8 E1.m \ `.
/ / \ | ,--. | / _,.._ \ \
/ / E1.1 \ | Y3 `. | | / Y7 | \
; | ___ | | ` W Y4 |... | `Y6 ,' | :
| | ,-' `. X2 | `--' | | `'' | |
: | | V Y2 | \ _ / | | ;
\ | `-Y1,,' | \ .' Y5 / \ ,-Y8'`- / /
\ \ / \ \_' / X9 `. ,'/ /
`. \ X3 `.__,,' `._ Y9'',' ,'
` `._ _,' ___.......X7_ `---' ,'
` `---' ,-' `-. -'
`---. `. E1.3 Z _' _.--'
`-----. \---.......---' _.---''
`----------------''

<---------------- Enterprise E1 ---------------->

Figure 1: Enterprise-within-Enterprise Framework

Figure 1 depicts an enterprise 'E1' connected to the global IPv6/IPv4
Internet via routers 'R1' through 'Rn' and additional enterprises
'E2' through 'EN' that also connect to the global Internet. Within
the 'E1' commons, there may be arbitrarily-many IPv4 hosts, routers
and networks (not shown in the diagram) over which IPv4 packets can
be forwarded and IPv6 packets can be tunneled. There may also be
many internal enterprises/sites enterprises 'E1.1' through 'E1.m' (shown in the
diagram) that interconnect within the 'E1' commons via Border Routers
(BRs) depicted as 'X1' through 'X9' (where 'X1' through 'X9' see 'R1'
through 'Rn' as Border Gateways (BGs)). Within each 'E1.*'
enterprise, there may also be arbitrarily-many IPv4 networks/nodes as
well as lower layer enterprises/sites enterprises that interconnect within the 'E1.*'
commons via BRs depicted as 'Y1' through 'Y9' in the diagram (where
'Y1' through 'Y9' see 'X1' through 'X9' as BGs). This hierarchical
decomposition can be recursively nested as deeply as desired, and
ultimately terminates at singleton IPv6/IPv4 dual-stack systems such
as those depicted as 'V', 'W' and 'Z' in the diagram.

It is important to note that dual-stack systems such as 'V', 'W' and
'Z' may be simple IPv6/IPv4 hosts, or they may be BRs that attach
arbitrarily-complex IPv6-only edge networks. Such IPv6-only edge
networks could be as simple as a home network behind a residential
gateway, or as complex as a major corporate/academic campus, a large
service provider network, etc.

Again, this enterprise-within-enterprise framework can be recursively
nested as broadly and deeply as desired. From the ultimate level of
the hierarchy, consider now that the global Internet itself can be
viewed as an "enterprise" that interconnects E1 through EN such that
all RANGER architectural principles apply equally within the global
Internet context.

As a specific case in point, the future global Aeronautical
Telecommuncations Network (ATN) under development within the civil
aviation industry [I-D.bauer-mext-aero-topology] will take the form
of a large enterprise network that appears as an Internet unto
itself, i.e., exactly as depicted for 'E1' in Figure 1. Within the
ATN, there will be many Air Communications Service Provider (ACSP)
and Air Navigation Service Provider (ANSP) networks organized as
autonomous systems internal to the ATN, i.e., exactly as depicted for
'E1.*' in the diagram. The ACSP/ANSP network BGs will participate in
a BGP instance internal to the ATN, and may themselves run
independent BGP instances internally and be further sub-divided into
enterprises/sites
enterprises organized as regional, organizational, functional, etc.
compartments. It is important to note that, while ACSPs/ANSPs within
the ATN share a common objective of safety-of-flight for civil
aviation services, there may be competing business/social/political
interests between them such that the ATN is not necessarily "one big
happy family". Therefore, the model parallels that of the global
Internet itself.

Such an operational framework may indeed be the case for many next-
generation enterprises. In particular, although the inner-workings
of all enterprises will require a mutual level of cooperative active
management at some a certain level, free market forces, business
objectives, political alliances, etc. may drive internal competition.

3.2. Virtual Enterprise Traversal (VET)

Within the enterprise-within-enterprise framework outlined in
Section 3.1, the RANGER architecture is based on an overlay network
approach that manifested through Virtual Enterprise Traversal (VET)
[I-D.templin-autoconf-dhcp]. The approach uses IPv6 routing and addressing to span an enterprise
via automatic IPv6-in-IPv4 IPv6-in-
IPv4 tunneling over within a hierarchy of child enterprises that are
either configured within the same addressing region of a larger
enterprise or use enterprise-local-scope their own enterprise-local IPv4 routing and
addressing internally. These logically and/or physically disjoint
IPv4
child enterprises are "glued together" by IPv6 BRs/BGs, with each BR
requesting an IPv6 prefix delegation from a delegating BG.
Additionally, fault tolerance and multihoming is naturally afforded
through configuration of multiple BGs per child enterprise.

Figure 2 below depits a vertical slice (albeit represented
horizontally) from the enterprise-within-enterprise framework shown
in Figure 1, where an IPv6 host 'H' that is deeply nested within
Enterprise 'E1' connects to IPv6 server 'S1' located somewhere on the
IPv6 Internet:
+------+
| IPv6 |
|Server|
" " " " " " " "" " " " " " " " " " " " " " " " | S1 |
" 2001:DB8:0:0::/56 *:0::/48 *:0::/40 " +--+---+
" . . . . . . . . . . . . . . . " |
" . . . . . . " |
" . +----+ v +--- + v +----+ v +----+ +-----+-------+
" . | V += e =+ Y1 += e =+ X2 += e =+ R2 +==+ Internet |
" . +-+--+ t +----+ t +----+ t +----+ +-----+-------+
" . | 1 . . 2 . . 3 . " |
" . H . . . . . " |
" . . . . . . . . . . . . . . " +--+---+
" <E1.1.1> <E1.1> <E1> " | IPv4 |
" 10/8 10/8 10/8 " |Server|
" " " " " " " " " " " " " " "" " " " " " " " | S2 |
<-- Enterprise E1 --> +------+

Figure 2: Virutal Enterprise Traversal within the RANGER Architecture

Within this vertical slice, Figure 2 depicts each enterprise within
the 'E1' hierarchy as spanned by automatic IPv6-in-IPv4 tunnels
'vet1' through 'vet3' manifested through Virtual Enterprise Traversal
(VET) [I-D.templin-autoconf-dhcp]. Each 'vet*' interface within this
framework is Non-Broadcast, Multiple Access (NBMA), and connects all
BRs within the same enterprise. Each enterprise within the 'E1'
hierarchy may comprise a smaller topological region within a larger
IPv4 routing region, or they may configure an independent routing and
addressing plan from a common (but spatially reused) limited-scope
IPv4 prefix, e.g., depicted as '10/8' in the diagram. The BR for
each 'E1*' enterprise receives an IPv6 prefix delegation from a
delegating BG, depicted above as sub-delegations of the prefix '2001:DB8::/40'.

Along with the Subnetwork Encapsulation and Adaptation Layer (SEAL -
see: Section 3.4), '2001:
DB8::/40'.

VET specifies the necessary mechanisms and operational practices to
manifest the RANGER architecture in a wide range of use cases such as depicted
in the example above as well as above. The use of VET in any such similar example. In
particular, conjunction with the
Subnetwork Encapsulation and Adaptation Layer (SEAL - see:

Section 3.4) may also be essential in certain deployments to avoid
issues related to ICMP spoofing and tunnel encapsulation overhead.

VET allows 'V', 'Y1', 'X2' and 'R2' to configure separate 'vet*'
interfaces for each enterprise they connect to, and to discover BGs
through a static name service resolution (or, mapping) as specified
in [I-D.templin-autoconf-dhcp]. After tunnels 'vet1' through 'vet3'
are established and BG's discovered, the BRs connected to a 'vet*'
interface can run an IPv6 routing protocol such as OSPVFv3 [RFC5340]
and form adjacencies between themselves in an on-demand fashion while
treating the 'vet*' interface as an ordinary IPv6 link. It is
important to note that adjacencies can be formed on-demand and
allowed to expire after idle periods such that a full mesh of links
need not be maintained. This allows an IPv6 overlay network that
spans 'E1' to automatically form and dynamically adapt to changing conditions within the
enterprise.

In the example shown in Figure 2, a simple IPv6 host 'H' is attached
to a shared link with IPv6/IPv4 dual stack node 'V'. IPv6 host 'H'
uses standard IPv6 neighbor discovery mechanisms to discover 'V' as a
default IPv6 router that can forward its packets off the local link,
while 'V' sees node 'Y1' as a BG that can be reached via 'vet1' and
that can forward packets toward IPv6 server 'S1'. Similarly, node
'Y1' is a BR for the enterprise spanned by 'vet2' that sees 'X2' as a
BG, and node 'X2' is a BR for 'vet3' that sees 'R2' as a BG that
connects 'E1' to the global IPv6 Internet.

In a second example, Figure 3 depicts an instance of on-demand
discovery of more-specific routes in which an IPv6 host 'H' connects
to an IPv6 server 'J' located in a different organizational entity
within 'E1':

+------+
| IPv6 |
|Server|
" " " " " " " "" " " " " " " " " " " " " " " " | S1 |
" 2001:DB8:0:0::/56 *0:0::/48 *0:0::/40 " +--+---+
" . . . . . . . . . . . . . . . " |
" . . . . . . " |
" . +----+ v +----+ v +----+ +----+ +-----+-------+
" . | V += e =+ Y1 += e =+ X2 += =+ R2 +==+ Internet |
" . +-+--+ t +----+ t +----+ +----+ +-----+-------+
" . | 1 . . 2 . . . " |
" . H . . . . v . " |
" . . . . . . . . . . . e . " +--+---+
" . t . " | IPv4 |
" . . . . . . , . 3 . " |Server|
" . +----+ v +----+ . " | S2 |
" . | Z += e =+ X7 += . " +------+
" . +-+--+ t +----+ . "
" . | 4 . . . "
" . J . . . . . "
" . . . . . . . "
" 2001:DB8:1:0::/56 *1:0::/40 "
" " " " " " " " " " " " " " "" " " " " " " "
<-- Enterprise E1 -->

Figure 3: On-Demand Discovery within the RANGER Architecture

In this scenario, tunnel interfaces 'vet1' through 'vet4' as well as
IPv6 prefix delegations have been established through the enterprise
autoconfiguration procedures specified in
[I-D.templin-autoconf-dhcp]. When IPv6 host 'H' sends IPv6 packets
to server 'J', however, unless IPv6 routing information is available
BR 'X2' must determine that 'J' can be reached using a more direct
route via 'X7' across the 'E1' commons. To do so, 'X2' can perform
an on-demand mapping lookup, or perform
an on-demand mapping lookup by consulting the enterprise name service
as specified in[I-D.templin-autoconf-dhcp]. Alternatively, 'X2' can
send the packet to default router 'R2', and 'R2' can send return an ICMPv6
redirect message indicating that 'J' can be reached via a more direct
route through 'X7'.

It is specifically worth noting that, in both of the previous
examples, a BR may have potentially many VET interfaces over which it
can connect to the BRs/BGs of potentially many "sibling" enterprises/
sites neighboring
enterprises across the commons.

3.3. Support for IPv4 Services

While the IPv6 overlay network that spans 'E1' provides a fully-
connected routing and addressing capability for IPv6 services, access
to legacy IPv4 services will still be required for an extended (and
possibly indefinite) period. Figure 4 below depicts the applicable
IPv4 service access models for the RANGER architecture:

+------+
| IPv6 |
|Server|
" " " " " " " "" " " " " " " " " " " " " " " " | S1 |
" 2001:DB8:0:0::/56 *:0::/48 *:0::/40 " +--+---+
" . . . . . . . . . . . . . . . " |
" . . . . . . " |
" . +----+ v +--- + v +----+ v +----+ +-----+-------+
" . | V += e =+ Y1 += e =+ X2 += e =+ R2 +==+ Internet |
" . +----+ t +----+ t +----+ t +----+ +-----+-------+
" . 1 . . 2 . . 3 . " |
" . K L . . . . M . " |
" . . . . . . . . . . . . . . " +--+---+
" <E1.1.1> <E1.1> <E1> " | IPv4 |
" 10/8 10/8 10/8 " |Server|
" " " " " " " " " " " " " " "" " " " " " " " | S2 |
<-- Enterprise E1 --> +------+

Figure 4: IPv4 Service Access in the RANGER Architecture

In a first instance, an IPv4 client 'K' within enterprise 'E1.1.1'
can access IPv4 service 'L' within the same enterprise as-normal and
without the need for any IPv6-in-IPv4 encapsulation. Instead, a
"mapping" is done through a simple name lookup within the enterprise-
local name service deployed in 'E1.1.1', and enterprise-local native
IPv4 services are used. In many instances, this may indeed be the
preferred service access model even when IPv6 services are widely
deployed due to factors such as inability to replace legacy IPv4
applications, IPv6 header overhead avoidance, etc.

In a second instance, IPv4 client 'K' can access IPv4 server 'S2' on
the global IPv4 Internet in a number of ways. First, if the
recursively nested enterprises are all configured within the same
IPv4 routing region within E1, 'K' can simply forward its packets
toward 'R2' that acts as an IPv4 Network Address Translator (NAT)
and/or an ordinary IPv4 enterprise border router. Secondly, if the
recursively nested enterprises are configured within disjoint IPv4
routing regions, all routers 'Y1', 'X2' and 'R2' can provide an IPv4 Network Address Translation
(NAT) capability,
NAT capability however this approach requires multiple instances of
stateful NAT devices on the path which can lead to an overall degree
of brittleness and intolerance to routing changes. As a
second alternative, Instead, 'E1'
could instead deploy a "Carrier-Grade NAT (CGN)" at 'R2' (i.e., at the
enterprise border with the global Internet) and E1.1.1 could configure discover
'Y1' as an IPv4 default router. 'Y1' could then use the "dual-stack-lite" "dual-stack-
lite" approach in which it uses IPv4-in-IPv6-in-IPv4 tunneling to
convey the IPv4 packets from 'K' to the CGN at 'R2', which then
decapsulates and translates the inner IPv4 packets before sending
them on to 'S2'. As a third alternative, Finally, 'K' could be configured as an IPv6-only
node and use standard IPv6 routing to reach an IPv6/IPv4 translator
located at 'R2'. an IPv6 BR for the enterprise in which 'S2' resides'. The
translator would then use IPv6-to-IPv4 translation before sending
packets onwards toward 'S2'. These and other alternatives are
discussed in [I-D.wing-nat-pt-replacement-comparison].

In a final instance, the RANGER architecture currently makes no
provisions for an IPv4 client 'K' to use IPv4-only services to can access an IPv4 server 'M' in
a different enterprise within 'E1' that
configures a E1 as long as both enterprises are
configured over the same underlying IPv4 routing region. If the
enterprises are configured over disjoint addressing domain. Until an architected
approach is devised, 'K' IPv4 routing regions,
however, to K' would only be able to access 'M' using IPv6-
only IPv6-only
services.

3.4. Subnetwork Encapsulation and Adaptation Layer (SEAL)

Whenever the BRs of disjoint enterprises/sites enterprises are joined across a commons,
mechanisms that rely on ICMP feedback from routers within the network
may become brittle or susceptible to spoofing attacks. This is due
to the fact that ICMP messages can be lost due to congestion or
packet filtering gateways, and that network middleboxes are
essentially "anonymous" and may include insufficient information in
ICMPs that can be used to authenticate their source. ICMP messages
can therefore be forged by anonymous attackers, e.g., from a rogue
node within an enterprise that has malicious intent toward another
enterprise.

The Subnetwork Encapsulation and Encapsulation Layer (SEAL) provides
effective means for BRs to avoid these shortcomings by accepting only
authenticated feedback from correspondent BRs that can be validated
as Potential Routers topologically-correct routers within the commons (i.e., the
subnetwork) using the Potential Router List (PRL) discovery
mechanisms of [I-D.templin-autoconf-dhcp]. Moreover, SEAL does not
require reliable delivery of all ICMPs, but rather supports continued
operation even if some/many ICMPs are lost. Finally, SEAL adapts to
subnetworks that contain links with diverse bandwidth and MTU size
properties, and indeed allows for discovery and eradication of
marginal links.

The advantages of using SEAL within the RANGER enterprise-within-
enterprise framework are tangible, and compare favorably with the
alternative of deploying an all-IPv6 infrastructure even for clean-
slate deployments. This is especially true within enterprises that
provide a commons for joining organizational/political/functional
entities with a spirit of mutual cooperation but with competing
interests or objectives.

3.5. Mobility Management

When a mobile IPv6 node within an enterprise network moves to a new
IPv6 link, it can use mobility management mechanisms such as Mobile
IPv6 [RFC3775] or HIP [RFC4423] to maintain a stable identifier even
as it moves between foreign links.

When a mobile BR moves to a new enterprise, it can renumber its IPv4
address(es) (i.e., its locators) and communicate these changes to
peers using a mechanism such as MobIKE [RFC4555]. [RFC4555], dynaic updates to
the DNS, etc. In that case, it can still retain its IPv6 addresses
and/or prefixes without need for renumbering. This approach is
especially useful for maintaining continuity for the provider-
independent IPv6 prefixes owned by the BR.

4. Initiatives Related to RANGER/VET/SEAL

4.1. 6over4 and ISATAP

Long before the RANGER architecture and VET/SEAL specifications were
published, 6over4 [RFC2529] specified a means for automatic tunneling
of unicast/multicast IPv6 packets over multicast-capable IPv4
enterprises, however it was unable to function in enterprises that
did not support a full deployment of IPv4 multicast services.

To address these shortcomings, ISATAP (a unicast-only variant of
6over4) [RFC5214] was specified and widely implemented among major
software and equipment vendor products. ISATAP provides unicast-only
neighbor discovery mechanisms and also adds a means for determining
whether a node on an ISATAP interface is authorized to act as an IPv6
router; namely, the Potential Router List (PRL).

VET provides a functional superset of the 6over4 and ISATAP
mechanisms; VET further combines with SEAL to provide the functional
elements of the RANGER architecture.

4.2. The Locator Identifier Split Protocol (LISP)

The Locator-Identifier Split Protocol (LISP) [I-D.farinacci-lisp]
proposes a map-and-encaps architecture for scalable routing and
addressing within the global Internet Default Free Zone (DFZ). LISP
is

LISP, and a number of other proposals being discussed in essence the Routing
Research Group, share a specific manifestation number of properties with the RANGER architecture
applied to solution
proposed here. They may therefore be architecturally consistent with
the global Internetworking use case. All RANGER
architectural principles therefore apply equally to LISP. architecture.

5. IANA Considerations

There are no IANA considerations for this document.

6. Security Considerations

Communications between endpoints within different enterprise networks within an
enterprise are carried across a commons that joins organizational
entities with a mutual spirit of cooperation, but between which there
may be competing business/sociological/political interests. As a
result, mechanisms that rely on feedback from routers on the path may
become brittle or susceptible to spoofing attacks. This is due to
the fact that IP packets can be lost due to congestion or packet
filtering gateways, and that the source addresses of IP packets can
be forged. IP packets can therefore be generated by anonymous
attackers, e.g., from a rogue node within a third-party enterprise
that has malicious intent toward a victim.

Path MTU discovery is an example of a mechanism that relies on ICMP
feedback from routers on the path, and as such is susceptible to
these issues. For IPv4, a common workaround is to disable Path MTU
Discovery and let fragmentation occur in the network if it must. For
IPv6, lack of fragmentation support in the network precludes this
option such that the mitigation typically recommended is to discard
ICMP messages that contain insufficient information and/or to operate
with the minimum IPv6 path MTU. This example extends also to other
mechanisms that either rely on or are enhanced by feedback from
network devices, however attack vectors based on non-ICMP messages
are also subject for concern.

The RANGER architecture supports effective mitigations for attacks
such as distributed denial-of-service, traffic amplification, etc.
In particular, when VETand SEAL are is used, enterprise BGs can use
the identification encoded in the SEAL header as well as ingress
filtering to determine if a message has come from a topologically-
correct enterprise located across the commons. This allows
enterprises to employ effective mitigations at their borders without
the requirement for mutual cooperation from other enterprises. When
source address spoofing by nodes located within the commons is also
subject for concern, additional securing mechanisms such as tunnel-
mode IPsec between enterprise BGs can also be used.

While the RANGER architecture does not in itself address security
considerations, it proposes an architectural framework for functional
specifications that do. Security concerns with tunneling along with
recommendations that are compatible with the RANGER architecture are
found in [I-D.ietf-v6ops-tunnel-security-concerns].

7. Related Work

The RANGER architecture principles can be traced to the deliberations
of the ROAD group in January 1992 [RFC1380], and likely also to other
early works including Nimrod [RFC1753]. [RFC1955] captures the high-
level architectural aspects of the ROAD group deliberations in a "New
Scheme for Internet Routing and Addressing [ENCAPS] for IPNG".

8. Acknowledgements

This work was inspired through the encouragement of the Boeing DC&NT
network technology team and through the communications of the IESG.

Many individuals have contributed to the architectural principles
that form the basis for RANGER over the course of many years.

8. References

9.1.

8.1. Normative References

[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
September 1981.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.

9.2.

8.2. Informative References

[CATENET] Pouzin, L., "A Proposal for Interconnecting Packet
Switching Networks", May 1974.

[I-D.arkko-townsley-coexistence]
Arkko, J. and M. Townsley, "IPv4 Run-Out and IPv4-IPv6 Co-
Existence Scenarios", draft-arkko-townsley-coexistence-00
(work in progress), September 2008.

[I-D.bauer-mext-aero-topology]
Bauer, C. and S. Ayaz, "ATN Topology Considerations for
Aeronautical NEMO RO", draft-bauer-mext-aero-topology-00
(work in progress), July 2008.

[I-D.farinacci-lisp]
Farinacci, D., Fuller, V., Oran, D., Meyer, D., and S.
Brim, "Locator/ID Separation Protocol (LISP)",
draft-farinacci-lisp-09 (work in progress), October 2008.

[I-D.ietf-v6ops-tunnel-security-concerns]
Hoagland, J., Krishnan, S., and D. Thaler, "Security
Concerns With IP Tunneling",
draft-ietf-v6ops-tunnel-security-concerns-01 (work in
progress), October 2008.

[I-D.templin-autoconf-dhcp]
Templin, F., "Virtual Enterprise Traversal (VET)",
draft-templin-autoconf-dhcp-18
draft-templin-autoconf-dhcp-20 (work in progress),
October 2008.

[I-D.templin-seal]
Templin, F., "The Subnetwork Encapsulation and Adaptation
Layer (SEAL)", draft-templin-seal-23 (work in progress),
August 2008.

[I-D.wing-nat-pt-replacement-comparison]
Wing, D., Ward, D., and A. Durand, "A Comparison of
Proposals to Replace NAT-PT",
draft-wing-nat-pt-replacement-comparison-02 (work in
progress), September 2008.

[IEN48] Cerf, V., "The Catenet Model for Internetworking",
July 1978.

[RFC1380] Gross, P. and P. Almquist, "IESG Deliberations on Routing
and Addressing", RFC 1380, November 1992.

[RFC1753] Chiappa, J., "IPng Technical Requirements Of the Nimrod
Routing and Addressing Architecture", RFC 1753,
December 1994.

[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.

[RFC1955] Hinden, R., "New Scheme for Internet Routing and
Addressing (ENCAPS) for IPNG", RFC 1955, June 1996.

[RFC2529] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4
Domains without Explicit Tunnels", RFC 2529, March 1999.

[RFC2775] Carpenter, B., "Internet Transparency", RFC 2775,
February 2000.

[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004.

[RFC4423] Moskowitz, R. and P. Nikander, "Host Identity Protocol
(HIP) Architecture", RFC 4423, May 2006.

[RFC4555] Eronen, P., "IKEv2 Mobility and Multihoming Protocol
(MOBIKE)", RFC 4555, June 2006.

[RFC4852] Bound, J., Pouffary, Y., Klynsma, S., Chown, T., and D.
Green, "IPv6 Enterprise Network Analysis - IP Layer 3
Focus", RFC 4852, April 2007.

[RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
March 2008.

[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.

Author's Address

Fred L. Templin (editor)
Boeing Phantom Works
P.O. Box 3707 MC 7L-49
Seattle, WA 98124
USA

Email: fltemplin@acm.org

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