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Versions: (draft-chown-v6ops-campus-transition)
00 01
IPv6 Operations T. Chown
Internet-Draft University of Southampton
Expires: April 18, 2007 October 15, 2006
IPv6 Campus Transition Scenario Description and Analysis
draft-ietf-v6ops-campus-transition-00
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
In this document we consider and analyse the specific scenario of
IPv6 transition and deployment in a large department of a university
campus network. The department is large enough to operate its own
instances of all the conventional university services including (for
example) web, DNS, email, filestore, interactive logins, and remote
and wireless access. The scenario is a dual-stack one, i.e.
transition to IPv6 means deploying IPv6 in the first instance (and
probably for some time) alongside IPv4. This analysis identifies the
available components for IPv6 transition, while validating the
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applicability of the IPv6 Enterprise Network Scenarios informational
text. It focuses on the network elements of the transition, rather
than the application elements.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Site Philosophy . . . . . . . . . . . . . . . . . . . . . 4
2. Discussion of Scenarios Network Infrastructure Components . . 5
2.1. Component 1: Enterprise Provider Requirements . . . . . . 5
2.2. Component 2: Enterprise Application Requirements . . . . . 6
2.3. Component 3: Enterprise IT Department Requirements . . . . 7
2.4. Component 4: Enterprise Network Management System . . . . 8
2.5. Component 5: Enterprise Network Interoperation and
Coexistence . . . . . . . . . . . . . . . . . . . . . . . 9
3. Discussion of Network Infrastructure Component Requirements . 10
3.1. DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Routing . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.3. Configuration of Hosts . . . . . . . . . . . . . . . . . . 10
3.4. Security . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5. Applications . . . . . . . . . . . . . . . . . . . . . . . 10
3.6. Network Management . . . . . . . . . . . . . . . . . . . . 11
3.7. Address Planning . . . . . . . . . . . . . . . . . . . . . 11
3.8. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 11
3.9. Multihoming . . . . . . . . . . . . . . . . . . . . . . . 11
4. Specific Scenario Component Review . . . . . . . . . . . . . . 12
4.1. Network Components . . . . . . . . . . . . . . . . . . . . 12
4.1.1. Physical connectivity (Layer 2) . . . . . . . . . . . 12
4.1.2. Routing and Logical subnets (Layer 3) . . . . . . . . 12
4.1.3. Firewall . . . . . . . . . . . . . . . . . . . . . . . 12
4.1.4. Intrusion Detection System . . . . . . . . . . . . . . 12
4.1.5. Management . . . . . . . . . . . . . . . . . . . . . . 12
4.1.6. Monitoring . . . . . . . . . . . . . . . . . . . . . . 12
4.1.7. Remote access . . . . . . . . . . . . . . . . . . . . 13
4.1.8. IPv6 External Access . . . . . . . . . . . . . . . . . 13
4.2. Address Allocation Components . . . . . . . . . . . . . . 13
4.2.1. IPv6 network prefix allocation . . . . . . . . . . . . 13
4.2.2. IPv6 Address allocation . . . . . . . . . . . . . . . 14
4.3. Services . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3.1. Email . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3.2. Web Hosting . . . . . . . . . . . . . . . . . . . . . 14
4.3.3. Databases . . . . . . . . . . . . . . . . . . . . . . 14
4.3.4. Directory Services . . . . . . . . . . . . . . . . . . 15
4.3.5. DNS . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3.6. PKI . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3.7. NTP . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3.8. Multicast . . . . . . . . . . . . . . . . . . . . . . 15
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4.3.9. Remote login . . . . . . . . . . . . . . . . . . . . . 15
4.3.10. File serving . . . . . . . . . . . . . . . . . . . . . 15
4.3.11. Backups . . . . . . . . . . . . . . . . . . . . . . . 16
4.4. Host and Device Platforms . . . . . . . . . . . . . . . . 16
4.4.1. Server platforms . . . . . . . . . . . . . . . . . . . 16
4.4.2. Desktop/laptop platforms . . . . . . . . . . . . . . . 16
4.4.3. PDA platforms . . . . . . . . . . . . . . . . . . . . 16
4.5. User Tools . . . . . . . . . . . . . . . . . . . . . . . . 17
4.5.1. Hardware . . . . . . . . . . . . . . . . . . . . . . . 17
4.5.2. Mail Client . . . . . . . . . . . . . . . . . . . . . 17
4.5.3. Web Browser . . . . . . . . . . . . . . . . . . . . . 17
4.5.4. Conferencing systems . . . . . . . . . . . . . . . . . 17
4.5.5. Other collaboration tools . . . . . . . . . . . . . . 18
4.5.6. Usenet news client . . . . . . . . . . . . . . . . . . 18
4.5.7. Host communications . . . . . . . . . . . . . . . . . 18
4.6. Hard-coded address points . . . . . . . . . . . . . . . . 18
5. Analysis: Deployment Procedure . . . . . . . . . . . . . . . . 19
5.1. Advanced Planning . . . . . . . . . . . . . . . . . . . . 20
5.2. Testbed/Trial Deployment . . . . . . . . . . . . . . . . . 20
5.3. Production Deployment . . . . . . . . . . . . . . . . . . 21
6. Analysis: Dual-Stack Deployment - Transition toolbox . . . . . 22
7. Analysis: Considerations beyond the Scenarios Document . . . . 24
8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
12. Informative References . . . . . . . . . . . . . . . . . . . . 25
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 28
Intellectual Property and Copyright Statements . . . . . . . . . . 29
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1. Introduction
The scope of the enterprise network transition scenarios is very
large, much more so than that of the other three IPv6 transition
areas that have been studied within the IETF (ISP [9], unmanaged [7]
and 3GPP [14]). The IPv6 Enterprise Network Scenarios [11] have been
defined. In this document we present a specific case study area for
IPv6 transition, namely a large department (1,500 staff and students,
over 1,000 hosts) in an academic campus network. The purpose of this
document is to both define and analyse the IPv6 transition of such a
network, but also to test and validate the applicability of the IPv6
Enterprise Network Scenarios document to a specific example.
This document describes the transition at a campus, focusing on the
network elements. A separate document discusses ongoing issues with
campus transition, which are heavily related to the application
support and network management capability.
Our campus study falls under "Scenario 1" of the IPv6 Enterprise
Network Scenarios [11] document, i.e. the campus network is an
existing IPv4 network, where IPv6 is to be deployed in conjunction
with the IPv4 network.
"Scenario 1" has the assumption that the IPv4 network infrastructure
used has an equivalent capability in IPv6. This document analyses
that assumption. The Scenario also has requirements, i.e. that the
existing IPv4 network infrastructure is not disrupted, and that IPv6
should be equivalent or better than the network infrastructure in
IPv4. The Scenario also notes that it may also not be feasible to
deploy IPv6 on all parts of the network immediately.
These assumptions and requirements will be discussed later in this
text.
It should also be noted why Scenarios 2 and 3 did not apply to this
campus transition scenario. Scenario 2 talks of specific
applications, but in the campus case we wish to deploy IPv6
pervasively, in wired and wireless networks, as an enabler for
education and research, to encourage new application development.
Scenario 3 focuses on using IPv6 as the basis for most network
communication, but in the campus we already have a significant IPv4
deployment that will be utilised for the foreseeable future (Scenario
3 would perhaps be more appropriate for a greenfield deployment).
1.1. Site Philosophy
The site which is the subject of this study is a large departmental
network on a campus. That network (prior to transition) is an IPv4
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network with around 20 subnets, using a core network infrastructure
that combines switch-router functionality in central devices, with
switches at the network edge. The main switching equipment is all
VLAN capable. There are around 1,000 networked nodes and 1,500
users, not including transient wireless visitors.
The site wishes to deploy IPv6 dual-stack to support its own users
along with its teaching and research needs. The goal is to IPv6
enable the network (on the wire) and services (DNS, SMTP, etc) such
that the whole operation is dual-stack. This in due course would
allow IPv6-only devices to be deployed within the fully IPv6-capable
environment. Some network links may become IPv6-only in the future.
This text has evolved over time. When we began writing, the
department did not have IPv6 capability on its existing IPv4 routing
equipment, thus a deployment method was required until the next
procurement. We discuss that interim solution within this document,
and present the discussion from an initial point of an interim
parallel IPv6 deployment prior to unifying the IPv4 and IPv6 routing
on a single platform. Our initial deployment plan used a separate
IPv6 path into the department with a parallel routing infrastructure
for IPv6. In practice this meant that our initial deployment used a
parallel IPv6 routing infrastructure, using BSD routers, for over
three years, prior to a unified solution on a commercial platform.
2. Discussion of Scenarios Network Infrastructure Components
In this section, we look at the issues raised by following the
Scenarios Network Infrastructure Components of the IPv6 Enterprise
Network Scenarios [11] document, section 3.2. This section is
written from the perspective of pre-transition planning, although we
are writing the document having undergone transition.
2.1. Component 1: Enterprise Provider Requirements
The answers to the questions posed in this section of the IPv6
Enterprise Network Scenarios document are as follows:
o There is external access to/from the campus network, regional MAN
and National Research Network beyond.
o There are needs for access by remote staff, student and
researchers.
o It is a single site, with four buildings.
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o There are no leased lines or wide-area VPNs between remote
buildings.
o The department has 12 IPv4 Class C's, the campus has a Class B,
independent from its provider (assigned prior to use of CIDR).
o The IPv4 and IPv6 provider is the National Research and Education
Network (JANET in the UK). JANET provides a /48 IPv6 site prefix
for the university. The university offers a /52 prefix for the
department.
o The university and department make their own prefix allocations
for subnets.
o There is no multihoming, and thus no multihomed clients.
o The provider (JANET) offers an IPv6 Tunnel Broker [3] service and
a 6to4 [4] relay, though the campus has native IPv6 connectivity
via its regional MAN.
o There is no external IPv6 routing protocol needed due to the use
of static route configuration between the campus and the regional
network.
o There is no external data centre.
o IPv6 will run over the same access links to campus as IPv4 does
(the JANET backbone uses true dual stack, the regional MAN uses
6PE [19]). On campus, the IPv4 traffic to the department is
received through a Nokia IP740 firewall, the IPv6 traffic will
initially be received through a BSD firewall. Thus the access
links into the department for IPv4 and IPv6 are different, though
the goal in the longer term is to make them the same. (This
happened in 2006 when a new Checkpoint firewall was deployed.)
2.2. Component 2: Enterprise Application Requirements
Answers to the next IPv6 Enterprise Network Scenarios section are as
follows:
o The application inventory is discussed in the specific component
review in the next section.
o We expect the first applications to be moved will be the support
services, including DNS. The first applications should be the
common IPv4 applications, e.g. web, remote login and email, such
that IPv6 offers as least an equivalent service to IPv4 for the
core service applications.
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o The academic environment has a good mix of open source and
commercial software, predominantly either Microsoft or Linux, but
with a growing number of Mac OS/X users. Specific platforms are
reviewed in the component review in the next main section. Most
open source applications have been upgraded to allow IPv6
operation; others can be upgraded given time.
o The general goal is for applications to support both IPv4 or IPv6
operation, i.e. to be IP agnostic.
o There is no use of NAT in the department's network. Home users,
or users access into the network remotely from certain locations,
may experience NAT at their client side.
o NAT issues are relevant from the end-to-end perspective, for
establishment of end-to-end security where desired, and in
relation to IPv6 transition (remote access) methods that may be
run through NATs.
o There is a mix of internal and external applications. Where
limitations occur, it is mainly by policy not technology, e.g. as
implemented in firewall restrictions.
2.3. Component 3: Enterprise IT Department Requirements
Here we list responses to the next IPv6 Enterprise Network Scenarios
section on IT Department Requirements. Again, in this section we
write our comments from a pre-transition perspective.
o Ownership and support is all in-house.
o Remote VPNs are supported.
o No inter-site networking is required.
o No IP mobility support is required at this point, though we expect
to use Mobile IPv6 between the department network and a local
community wireless network, on our wireless LAN deployment as it
grows in size, and to pilot its use inter-campus.
o The IPv6 address plan for the department requires a /52 prefix.
o There is no detailed asset database, though one exists providing a
host inventory (for DNS and DHCP use).
o There are no geographically separate sites.
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o The internal IPv4 address assignment mechanism is DHCP for
clients, with manual configuration for servers. We thus expect to
use DHCPv6 for at least some, if not all, IPv6 clients. This will
depend on availability of DHCP client and server software.
o Internal IPv4 routing is static or uses RIP. We thus expect to
use RIPng internally.
o We expect our IPv6 network management policy to be very similar to
that for IPv4. Having coherent policies should make network
operation simpler.
o There is no QoS provision at present, largely due to the ample
campus bandwidth (1Gbit/s uplink).
o Security is applied through many technologies implementing our
policies, e.g. firewall, email scanning, wireless LAN access
controls. We expect similar policies for IPv6, but need to
analyse differences.
o Training will be done in-house.
o The impacted software components are discussed in the next main
section. Not all functions are upgradeable to IPv6; those that
are not are discussed in the analysis section. Some are, e.g. use
of OpenLDAP (IPv6 capable) as an interim step in place of MS
Active Directory (not IPv6 capable at the time of the analysis).
Our view is that if components cannot be given immediate IPv6
equivalents, this functionality will come in due course, and IPv4
transport can be used in the interim. But the goal is to
facilitate IPv6 capability.
o The impacted hardware components are discussed in the next main
section. Not all hardware is upgradeable, e.g. network printers.
There are no load balancing systems in use. There are wireless
LAN hosts in the network that are mobile, but currently the
wireless network is a single flat IPv4 subnet. There may be nodes
moving to external wireless networks (i.e. the local community
wireless network).
2.4. Component 4: Enterprise Network Management System
The responses to the next IPv6 Enterprise Network Scenarios section
are as follows:
o No performance management is required.
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o There are a number of network management and monitoring tools in
use, which will need to be used in a dual stack or IPv6 mode, e.g.
the nocol availability monitoring tools, and SNMP-based
management.
o The configuration management may include use of tools to configure
services including DNS and email.
o No policy management and enforcement tools are required.
o No detailed security management is required, though we expect to
manage the implementations including firewalls and intrusion
detection.
o We may need to manage the deployed transition tools and
mechanisms.
o We need to analyse the considerations IPv6 creates for network
management, e.g. use (or not) of RFC3041 privacy addresses. The
need for user privacy is recognised, but the need for simplified
management is also a strong consideration.
2.5. Component 5: Enterprise Network Interoperation and Coexistence
Answers to the final IPv6 Enterprise Network Scenarios section on
Coexistence are as follows:
o The platforms that are required to be IPv6 capable are listed in
the next main section.
o There is only one network ingress and egress point to the site
that needs to be IPv6 capable; this is a Gigabit Ethernet
interface.
o The required transition mechanisms are discussed in the analysis
section. We expect to mainly use the VLAN [17] mechanism for
internal IPv6 transport, with a parallel IPv6 routing
infrastructure based on BSD routers, until the core infrastructure
is able to support IPv6 (via upgrade or a new procurement).
o The transition to IPv6 will be enabled on the wire first, enabling
clients, with a phased introduction of service capability, as
discussed below in the analysis section.
o The preferred mechanism for interoperation with legacy nodes is to
use dual-stack and thus IPv4 to communicate to IPv4 nodes and IPv6
to communicate to IPv6 nodes. We have not identified any in-
house, non-upgradeable legacy applications.
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3. Discussion of Network Infrastructure Component Requirements
In this section, we discuss the network infrastructure component
requirements raised in the IPv6 Enterprise Network Scenarios [11]
document, in section 4.
3.1. DNS
BIND9 is used for our three internal name servers. The servers will
be made dual stack, to be available for IPv6 transport for local
dual-stack or IPv6-only nodes. The three servers will each be listed
with AAAA records, and AAAA glue added.
3.2. Routing
Internal routing is either statically configured or uses RIP. We
thus expect to use RIPng for internal IPv6 routing. The external
routing is statically configured for IPv4, and thus is likely to be
statically configured for IPv6.
3.3. Configuration of Hosts
IPv4 clients use DHCP for address and other configuration options.
We expect to use Dynamic Host Configuration Protocol for IPv6
(DHCPv6) [5] for IPv6 clients. This will require analysis of the
IPv4 and IPv6 Dual-Stack Issues for DHCPv6 [16]. We expect some
clients, especially in wireless LANs, to use IPv6 Stateless
Autoconfiguration [1], and these nodes will need support for
Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6
[6] for other configuration options, including the IPv6 address of a
local DNS resolver.
Although IPv6 offers Stateless Autoconfiguration, it is expected that
the managed environment will continue, driven from the asset
database, for some time. Thus DHCPv6 is required. Use of Stateless
Autoconfiguration implies a requirement for dynamic DNS updates for
such nodes. It is not yet decided how to apply or enforce that plan;
it may certainly be flexible with time.
3.4. Security
We need to identify new IPv6 related security considerations, and
those associated with transition mechanisms [20]. Site policies may
need to be updated as a result.
3.5. Applications
The Application Aspects of IPv6 Transition [10] document describes
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best porting practice for applications. There should also be
consideration for any required application proxies.
3.6. Network Management
The network management and monitoring systems will need to embrace
IPv6, and any transition mechanisms used to deploy IPv6. Monitoring
includes usage tracking (e.g. via MRTG) and availability monitoring
(e.g. via Nagios).
3.7. Address Planning
The department receives 12 Class C prefixes for IPv4 use, and uses
only globally routable addresses internally. The IPv4 address space
for the campus was obtained prior to CIDR, but the IPv6 address space
is allocated from the UK National Research Network (JANET) address
space under 2001:0630::/32. The university receives a /48 prefix,
which is 2001:0630:d0::/48. The department has a /52 allocation
within this block of 2001:0630:d0:0:/52.
IPv6 address assignment planning is discussed in the IPv6 Unicast
Address Assignment Considerations [18] text.
3.8. Multicast
IPv4 multicast is used for a number of applications, including the
AccessGrid. Connectivity is provided via the local campus and
regional network. We expect to use both IPv6 ASM (i.e. PIM-SM), and
we plan to make use of the Embedded-RP [8] technique. For bridging
between IPv4 and IPv6 multicast, we believe an IPv4 - IPv6 multicast
gateway [21] may prove valuable. Finally, we expect to make use of
source specific multicast (SSM) more heavily in IPv6, bringing IPv6
and SSM together in one deployment cycle.
The use of IPv6 multicast makes it much simpler for our site to
generate its own globally unique group addresses than is the case for
IPv4, where we need to use GLOP space from an upstream provider. For
IPv6, you can generate your own unique group address for regular or
Embedded-RP groups based on your unicast prefix (typically /48 or
/64). We expect to use Embedded-RP where possible, running our own
IPv6 RP to support our own content.
3.9. Multihoming
The site is not multihomed for IPv4, and thus will not be for IPv6.
This is typical for UK academic networks, but may change in due
course as resilience concerns rise.
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4. Specific Scenario Component Review
Here we describe specific technology in use now in the department.
Later in this section we discuss any items not included in the above
section, i.e. those not explicitly mentioned in the IPv6 Enterprise
Network Scenarios document. Note that not all applications and
services have at the time of writing been made IPv6 capable. A gap
analysis is the subject of a separate ongoing 'live' document. This
text aims to be a stable description of the processes and thinking
followed during our campus transition.
4.1. Network Components
4.1.1. Physical connectivity (Layer 2)
o Switched Ethernet
o Gigabit Ethernet
o Wireless networking (802.11b)
4.1.2. Routing and Logical subnets (Layer 3)
The hybrid Layer 2/3 routing equipment has approximately 20 internal
IPv4 subnets (in effect, routed VLANs). There is no specific
internal routing protocol used. There is a static route via the site
firewall to the main upstream provider (academic) running at 1Gbit/s.
4.1.3. Firewall
The firewall is currently Firewall-1 running on a Nokia IP740
hardware platform. There is one internal facing interface, one
external facing interface, and two DMZ interfaces, one for wired
hosts and one for the Wireless LAN provision.
4.1.4. Intrusion Detection System
Snort is used locally for IPv4 IDS.
4.1.5. Management
Some network management is performed by SNMP; there is no specific
package for this. There is a greater emphasis on monitoring than
explicitly in management.
4.1.6. Monitoring
A number of tools are used, to monitor network usage as well as
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systems availability, e.g. Nagios and MRTG. The network testing
tools include iperf, rude and crude.
4.1.7. Remote access
o Livingston Portmaster 56K/ISDN dialup (being phased out)
o RADIUS servers (running Radiator)
o (Microsoft) VPN servers
4.1.8. IPv6 External Access
o IPv6 connectivity will come via our regional network (which runs
6PE) through trunked (unrouted) VLANs across campus to our
departmental network. Because the existing IP firewall pre-
transition does not support IPv6, IPv6 will need to be transported
into the departmental network via a separate parallel IPv6 capable
firewall (e.g. a BSD system using pf).
4.2. Address Allocation Components
The department receives its IPv4 and IPv6 address allocations from
the University. For IPv4, the University has a Class B allocation
which is not aggregated under the JANET NREN. For IPv6, the
University receives its allocation from JANET.
4.2.1. IPv6 network prefix allocation
For IPv6, JANET has the prefix 2001:630::/32 from RIPE-NCC, as the
national academic ISP in the UK. The University has been allocated
2001:630:d0::/48 by JANET. The department transitioning will be
allocated a /52 size prefix under 2001:630:d0::/48, i.e. 2001:630:d0:
0::/52.
In the initial deployment, we expect that IPv4 and IPv6 subnets will
be congruent (and share the same VLANs). This is because the
existing subnet divisions are made for geographic or administrative
reasons that are not IP version dependent (e.g. by building location
or research group membership).
One advantage for IPv6 is that subnets will not need to be resized to
conserve or efficiently utilise address space as is the case
currently for IPv4 (as subnet host counts rise and fall for
administrative or research group growth/decline reasons).
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4.2.2. IPv6 Address allocation
It is expected that the network devices will use a combination of
address allocation mechanisms:
o Manually configured addresses (in some servers)
o Stateful DHCPv6 (probably in fixed, wired devices and some
servers)
o Stateless address autoconfiguration (probably in wireless and
mobile devices)
o RFC3041 privacy addresses (in some client devices)
For devices using stateless or RFC3041 mechanisms, a Stateless DHCPv6
server will be required for other (non-address) configuration
options, e.g. DNS and NTP servers.
4.3. Services
4.3.1. Email
There are three MX hosts for inbound email, and two main internal
mail servers. Sendmail is the MTA. POP and IMAP (and their secure
versions) are used for mail access, using the Cyrus IMAP open source
code. There is an MS Exchange server used by a growing proportion of
users (generally those wanting shared access to mail spools, e.g.
professors and secretaries). MailScanner is used for anti-spam/
anti-virus. This uses external services including various RBLs for
part of its spam checking. Successful reverse DNS lookup is required
for sendmail to accept internal SMTP connections for delivery.
4.3.2. Web Hosting
Web content hosting is provided either with Apache 2.x (open source)
or Microsoft IIS 5.0. Common components used to build systems with
are MySQL, PHP and Perl; these enable local tools such as Wikis to be
run.
4.3.3. Databases
All database systems are presented to users via a web interface,
including the financial systems. In some cases, e.g. student
records, ODBC-like access is required/used in to/out from the
department systems to the campus systems. Databases include: finance
records, people, projects and publications (offered using ePrints).
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4.3.4. Directory Services
The following are used:
o NIS
o LDAP
o Active Directory
o RADIUS
4.3.5. DNS
The three DNS servers are running BIND9. A DNS secondary is held at
another UK university site.
4.3.6. PKI
The department has at least 10 SSL certificates from Thawte,
including Web-signing certificates. No personal certificates are
supported by the department (though users may have their own).
4.3.7. NTP
The JANET NREN offers a stratum 0 NTP server. The department also
has a GPS-based NTP server built-in to its own RIPE NCC test traffic
server and an NTP device from Meinberg.
4.3.8. Multicast
PIM-SM IPv4 multicast is facilitated via a dedicated Cisco 7206
router, using a Rendezvous Point operated by our regional network.
This supports applications including the IPv4 AccessGrid conferencing
system. A number of bugs in the existing IPv4 routing equipment
prevent heavy use of IPv4 Multicast within the department network
(another reason that an IPv6 Multicast solution is desirable). An
IPv4 Multicast beacon is used for monitoring Multicast.
4.3.9. Remote login
Remote login access is offered via ssh, with sftp for file transfer.
Remote use of insecure protocols such as telnet and ftp is denied by
the firewall.
4.3.10. File serving
The main file servers are SGI systems, hosting large (multi-TB)
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standalone RAID arrays. The files are offered via NFS and Samba to
client systems. Our content (package) distribution server is hosted
on such a system.
4.3.11. Backups
Backups are run over SSH, which is IPv6-enabled. A site using a
proprietary remote backup solution may not yet have IPv6 capability.
4.4. Host and Device Platforms
4.4.1. Server platforms
These include:
o Windows 2003 server
o Windows 2000 server
o Windows NT
o Solaris 8
o Solaris 9
o Solaris 10
o RedHat Linux
o SGI Origin 300 (Irix 6.5.x)
4.4.2. Desktop/laptop platforms
These include:
o Windows 98, 2000, ME, XP
o Linux (various flavours)
o MacOS/X
o BSD (various flavours)
4.4.3. PDA platforms
These include:
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o Windows CE/.NET, Pocket PC
o PalmOS
o Familiar Linux on iPaQ
o Zaurus (Linux)
4.5. User Tools
These are non-exhaustive but representative application/platform
lists
4.5.1. Hardware
o Networked printers
o Networked webcams
4.5.2. Mail Client
o Outlook (various versions)
o Eudora
o Mutt
o Pine
4.5.3. Web Browser
o MS Internet Explorer
o Mozilla
o Firefox
o Safari
o Opera
4.5.4. Conferencing systems
o AccessGrid
o A dedicated H.323 system
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o MS Netmeeting
4.5.5. Other collaboration tools
o IRC
o Jabber
o MSN Messenger
o cvs
4.5.6. Usenet news client
o nn
o Mozilla
4.5.7. Host communications
o X11
o VNC
o PC Anywhere
4.6. Hard-coded address points
Usage of IPv4 hard-coded addresses is interesting for at least two
reasons. One is that it illustrates where IPv6 hard-coded addresses
may appear, and thus secondly it is useful to analyse which hard-
coded addresses may be barriers to smooth IPv6 renumbering. A
procedure for renumbering has been described in Procedures for
Renumbering an IPv6 Network without a Flag Day [12]. A non-
exhaustive list of instances of such addresses includes:
o Provider based prefix(es)
o Names resolved to IP addresses in firewall at startup time
o IP addresses in remote firewalls allowing access to remote
services
o IP-based authentication in remote systems allowing access to
online bibliographic resources
o IP address of both tunnel end points for IPv6 in IPv4 tunnel
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o Hard-coded IP subnet configuration information
o IP addresses for static route targets
o Blocked SMTP server IP list (spam sources)
o Web .htaccess and remote access controls
o Apache .Listen. directive on given IP address
o Configured multicast rendezvous point
o TCP wrapper files
o Samba configuration files
o DNS resolv.conf on Unix
o Nocol monitoring tool
o NIS/ypbind via the hosts file
o Some interface configurations
o Unix portmap security masks
o NIS security masks
The author is contributing to work in studying things to think about
in IPv6 renumbering [22], where the above issues will be considered.
5. Analysis: Deployment Procedure
In this section we document (retrospectively) the procedure we went
through in deploying IPv6 within our campus site.
The work described in this document has also been fed into the IPv6
Enterprise Analysis [23]. The reader is referred in particular to
Section 4 ("Wide-Scale Dual-Stack Deployment") and Section 7
("General issues and applicability for all Scenarios") which were
directly contributed from the work here.
As described in the IPv6 Enterprise Analysis [23] document, the
scenario here is one of wide-scale dual-stack deployment. The plan
for deployment follows the general guidelines of Section 7 of that
document, though we have expanded that description here from
subsequent experience.
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Note that our analysis does not include issues relating to deployment
of new IPv6-specific technology, e.g. MIPv6.
5.1. Advanced Planning
A first phase for deployment includes the following actions.
o Include IPv6 requirements in all future tenders. Consult to
understand IPv6 specification requirements for tenders; this may
prove particularly valuable where new IPv6 specific technology is
desirable, e.g. Embedded-RP support for Multicast.
o Identify your IPv6 ISP. This will most likely be your IPv4 ISP
also, but in some cases it may not be.
o Speak to your IPv6 ISP to acquire IPv6 address space (a /48
prefix) for your site; you will need this at some point, so may as
well acquire the space sooner rather than later. This will
include delegation of IPv6 forward and reverse DNS for your site.
Our campus address space is a /48 prefix allocated by JANET, under
their prefix of 2001:630::/32.
o Establish IPv6 training for operational staff, for administration
of host and router platforms.
o Investigate how to deploy basic IPv6 network services: DNS,
routing, host configuration.
o Encourage operational staff to get some IPv6 familiarity by trying
IPv6 through services such as a public or ISP-supported IPv6
tunnel broker [3].
o Review IPv6 security issues. IPv6 is enabled by default on many
host platforms; this should be considered when enforcing security
policies on systems and networks.
Following these action points should allow sites or networks to be
ready for a trial or pilot IPv6 deployment, and to have confidence
they understand and have control of their current - perhaps unwitting
- usage of IPv6 (from systems which have it enabled by default).
5.2. Testbed/Trial Deployment
In this stage a site is validating IPv6 for deployment, and will thus
take actions including the following:
o Assign and deploy an IPv6-capable router and (we recommend) a
firewall or filtering device.
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o Establish IPv6 connectivity to the IPv6 ISP. Sites might use a
tunnelled service, or check for any native IPv6 offering. In our
case, the connectivity is native IPv6 from JANET, via the regional
MAN (using 6PE [19]) and the campus (using a VLAN to carry IPv6
natively).
o Connect testbed host systems on the internal router interface,
using one subnet prefix (a /64) from the site's allocated IPv6 /48
prefix. At this stage your trial network may be standalone
(disconnected from other internal networks) or, as we did, it may
be that you dual-stack your existing IPv4 DMZ(s) for the pilot
phase.
o Enable IPv6 on the host systems, and test IPv6 functions on
services and applications (e.g. BIND for DNS, Apache for Web,
sendmail or exim for mail transport).
In parallel, other preparation can be undertaken for a production
deployment:
o Survey systems, applications and services for IPv6 capability,
including management, monitoring and access control devices and
systems. The Enterprise Scenarios text as evaluated earlier in
this document is a good basis to undertake this task from.
o Formulate an IPv6 address plan for your site/network. Our campus
has allocated the department network a /56 prefix that can grow
into a /52 prefix, i.e. the department can create in theory up to
256 IPv6 subnets initially. We discuss address planning issues in
a separate document on IPv6 addressing considerations [18].
o Discuss and document IPv6-related policies (e.g. use of Privacy
Addresses, and of stateless or stateful address assignment).
Once the site is satisfied in the testbed deployment, then a
production deployment can be considered, enabling IPv6 for
appropriate links and services.
5.3. Production Deployment
A production deployment includes the following action points:
o Plan which parts of the network will be IPv6-enabled, and which
existing subnets will be IPv6-enabled (made dual-stack). This may
be certain server subnets, a DMZ, or a Wireless LAN network, for
example.
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o Determine how your production IPv6 connectivity will be handled;
it can (ideally) be via a single dual-stack entry point, or
through separate IPv4 and IPv6 links.
o Enable IPv6, and IPv6 routing, such that IPv6 is on the wire,
prior to host system activation. Ensure filtering and firewall
policies are implemented as required.
o Add IPv6 address configuration to your DNS systems, and configure
them to respond over IPv4 or IPv6 transport.
o Deploy IPv6 support in appropriate management and monitoring
tools.
o Enable IPv6 in selected production services and applications (e.g.
Apache or IIS for web servers). In our case, we focused initially
on DNS (bind), mail/MX (sendmail) and web services (Apache) in
dual-stack mode.
o Include IPv6 transport in all ongoing security audit/penetration
tests.
o Support IPv4-IPv6 interworking. As there are not (yet) any IPv6-
only links on our site, interworking methods are not required.
Should IPv6-only devices be deployed on the dual-stack
infrastructure, we anticipate using proxy tools (web cache, SMTP
relay, etc) to support their access to legacy IPv4 services,
rather than deploying translation-based tools.
o Supporting remote users. These may connect via an IPv4 VPN and
then use an IPv6 connection over that VPN, or use the remote IPv6
services of your ISP (e.g. our ISP, JANET, runs a tunnel broker
and a 6to4 relay).
The depth of the IPv6 deployment may vary from site to site. By
enabling key services you make your site ready for a fuller
deployment, and gain confidence and experience in the technology,
which is good for your support staff, your students and staff and
researchers.
6. Analysis: Dual-Stack Deployment - Transition toolbox
Within our network we initially deployed IPv6 in parallel to IPv4,
using a VLAN-based method as cited below. This allowed us to pilot
IPv6 without risking adverse impact on our existing IPv4 platforms.
This method was used for over two years. Towards the end of its use,
the BSD platforms used to facilitate this were showing signs of
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strain under the load, in terms of pure unicast and multicast
forwarding strain under heavier traffic bursts. We have since
deployed a unified IPv4 and IPv6 routing platform from a single
vendor, which met all our IPv4 and IPv6 procurement requirements for
IPv4 and IPv6 unicast and multicast functions, including but not
limited to:
o IPv6 unicast routing protocols;
o IPv6 multicast routing protocols (PIM-SM, SSM);
o IPv6 multicast Embedded-RP support;
o IPv6 multicast MLD(v1 and v2) snooping.
We have used the following mechanisms in our department's transition
process:
o VLANs [17] to distribute IPv6 connectivity over the non-dual-stack
capable network infrastructure. This VLAN solution was an interim
step until full dual protocol capable equipment was deployed
during 2005;
o A Tunnel broker [3] for remote access, provided by our IPv6 ISP
(JANET). We initially deployed our own tunnel broker, but now
refer our home and roaming users to the JANET solution;
o A 6to4 [4] relay for remote access, provided by our IPv6 ISP.
Again, we used to run our own relay, but the relay operated by our
IPv6 ISP is perfectly adequate at this time for communicating with
6to4 sites. We do not believe 6to4 is an acceptable solution as a
campus connectivity method (because we do not then use our own
IPv6 address space as allocated by JANET, and 6to4 itself is prone
to failure and abuse).
We do NOT currently see a requirement for:
o NAT-PT [2], because we are dual-stack with no IPv6-only networks
(yet), and as we introduce such networks, or IPv6-only nodes in
the dual-stack networks, we expect to use application layer
gateways and proxies for legacy IPv4 access. If and when we do
deploy an IPv6-only link, and ALGs are not sufficient, we would
look at DSTM as a solution in preference NAT-PT;
o ISATAP [13], because we prefer to use a structured internal IPv6
deployment, and are doing so in a pervasive fashion (i.e. not as a
sparse deployment). ISATAP may be useful for sparse deployment of
IPv6 in sites who are happy to IPv6 pilot in a less structured
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fashion;
o We considered deploying a Teredo [15] relay to support home users
behind NATs, but chose not to do so since the tunnel broker
service supports NAT traversal, and we feel it offers better
management and monitoring facilities. This decision may be
reviewed should Windows Vista ship with Teredo enabled by default.
At the time of writing the status of Teredo in Vista is not
finalised (Vista is not released).
7. Analysis: Considerations beyond the Scenarios Document
Here we mention issues or scenario components that were not
explicitly listed in the IPv6 Enterprise Network Scenarios document.
Due to the scope, that document could not embrace all details. We
mention here components that other sites may also wish to consider:
o Support for WLAN and other access control. One solution is to use
802.1x which is IP-agnostic as a Layer 2 port control mechanism.
o Consideration for hard-coded addresses.
8. Summary
In this document we have analysed the specific campus transition
scenario for the author's site, and reported the analysis for the
benefit of others who may be in a similar scenario, or for whom parts
of the scenario are relevant.
In our case transition does not mean from IPv4 only to IPv6 only,
rather from IPv4 only to a dual-stack environment that could support
IPv6 only nodes at a later date. We would probably best describe the
process as dual stack integration.
We have described how a phased approach to transition can be adopted
at a campus site (or part thereof), from a planning stage through a
pilot to a fuller deployment. During our transition we initially ran
a parallel IPv6 routing infrastructure, then in 2005 unified the
routing to a single platform, for unicast and multicast IPv6. We
enabled key services for dual-stack operation from the outset (DNS,
web and mail/MX) and have enabled other services as and when they
have become available. The VLAN-based interim step was useful for
two years until a dual-protocol solution could be procured.
We do not discuss detailed availability of IPv6 capability in the
services, platforms and user tools described in Section 4 above in
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this text. An ongoing gap analysis is being undertaken in a separate
text. For the purposes of our network-oriented transition, we are
happy that the path taken and current solution is stable and
complete.
The deployment has now been in full dual-stack operation for over a
year, with key services enabled (including public-facing DNS, SMTP,
web) without adverse effects on the IPv4 service. The author
welcomes discussion with other sites that are undergoing or have
undergone a similar transition or integration process.
9. Acknowledgements
Discussions with fellow participants on the 6NET and Euro6IX projects
have been valuable.
10. IANA Considerations
The document contains no IANA considerations.
11. Security Considerations
There are no specific new considerations from this scenario
description and analysis.
12. Informative References
[1] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[2] Tsirtsis, G. and P. Srisuresh, "Network Address Translation -
Protocol Translation (NAT-PT)", RFC 2766, February 2000.
[3] Durand, A., Fasano, P., Guardini, I., and D. Lento, "IPv6
Tunnel Broker", RFC 3053, January 2001.
[4] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via
IPv4 Clouds", RFC 3056, February 2001.
[5] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[6] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
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[7] Huitema, C., Austein, R., Satapati, S., and R. van der Pol,
"Evaluation of IPv6 Transition Mechanisms for Unmanaged
Networks", RFC 3904, September 2004.
[8] Savola, P. and B. Haberman, "Embedding the Rendezvous Point
(RP) Address in an IPv6 Multicast Address", RFC 3956,
November 2004.
[9] Lind, M., Ksinant, V., Park, S., Baudot, A., and P. Savola,
"Scenarios and Analysis for Introducing IPv6 into ISP
Networks", RFC 4029, March 2005.
[10] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E. Castro,
"Application Aspects of IPv6 Transition", RFC 4038, March 2005.
[11] Bound, J., "IPv6 Enterprise Network Scenarios", RFC 4057,
June 2005.
[12] Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering
an IPv6 Network without a Flag Day", RFC 4192, September 2005.
[13] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra-
Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 4214,
October 2005.
[14] Wiljakka, J., "Analysis on IPv6 Transition in Third Generation
Partnership Project (3GPP) Networks", RFC 4215, October 2005.
[15] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network
Address Translations (NATs)", RFC 4380, February 2006.
[16] Chown, T., Venaas, S., and C. Strauf, "Dynamic Host
Configuration Protocol (DHCP): IPv4 and IPv6 Dual-Stack
Issues", RFC 4477, May 2006.
[17] Chown, T., "Use of VLANs for IPv4-IPv6 Coexistence in
Enterprise Networks", RFC 4554, June 2006.
[18] Velde, G., "IPv6 Unicast Address Assignment Considerations",
draft-ietf-v6ops-addcon-01 (work in progress), July 2006.
[19] Clercq, J., "Connecting IPv6 Islands over IPv4 MPLS using IPv6
Provider Edge Routers (6PE)", draft-ooms-v6ops-bgp-tunnel-06
(work in progress), January 2006.
[20] Davies, E., "IPv6 Transition/Co-existence Security
Considerations", draft-ietf-v6ops-security-overview-05 (work in
progress), September 2006.
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[21] Venaas, S., "An IPv4 - IPv6 multicast gateway",
draft-venaas-mboned-v4v6mcastgw-00 (work in progress),
February 2003.
[22] Chown, T., "Things to think about when Renumbering an IPv6
network", draft-chown-v6ops-renumber-thinkabout-05 (work in
progress), September 2006.
[23] Bound, J., "IPv6 Enterprise Network Analysis",
draft-ietf-v6ops-ent-analysis-06 (work in progress), June 2006.
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Author's Address
Tim Chown
University of Southampton
School of Electronics and Computer Science
Southampton, Hampshire SO17 1BJ
United Kingdom
Email: tjc@ecs.soton.ac.uk
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