Documentation > Architectures > SIIT-DC

SIIT-DC

Index

  1. Introduction
  2. Sample Network
  3. Configuration

Introduction

This document is a summary of the SIIT-DC architecture, and a small walkthrough that builds it using Jool.

SIIT-DC is an improvement over traditional SIIT where EAMs are introduced and standardized. With this, IPv4 address usage is optimized and IPv4 address embedding (in IPv6 servers) becomes redundant.

Sample Network

This is the sample architecture from draft-siit-dc section 3:

Fig.1 - Network Overview

n6 is a random IPv6 node. s6 is one of your Data Centre servers (IPv6). n4 is a random IPv4 node. BR (“Border Relay”) is an SIIT.

2001:db8:46::/96 is routed to BR’s Data Centre-facing interface, and similarly, 192.0.2.1/32 (or covering aggregate) is routed to BR’s IPv4 Internet-facing interface. This is done using standard IP routing techniques.

The jist of SIIT-DC is n6 can use s6’s IPv6-only service using normal IPv6 connectivity, while n4 can use it via BR.

This will be the expected packet flow for n6:

Fig.2 - n6 Packet Flow

And this will be the expected packet flow for n4:

Fig.3 - n4 Packet Flow

Some properties of this are:

  • Mostly Single (IPv6) Stack operation (in the Data Centre). This simplifies maintenance as running one protocol is simpler than two.
  • Native IPv6 traffic is never modified at all.
  • Scales elegantly (Fully stateless operation, which can be made redundant painlessly).
  • Can optimize IPv4 address usage within the Data Centre (because it doesn’t impose restrictions on the servers’ IPv6 addresses).
  • Promotes IPv6 deployment (IPv4 end-user connectivity becomes a service provided by the network).
  • If you want to stop needing IPv4 in the future, all you need to do is shut down BR.

Configuration

Networking commands aside, this is Jool on BR:

# modprobe jool_siit pool6=2001:db8:46::/96
# jool_siit --eamt --add 192.0.2.1 2001:db8:12:34::1

For every server you want to publish on IPv4, you add one EAMT entry (as above) and appropriate IPv4 DNS records.

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