Zte ZXR10 ZSR V2 Configuration Manual page 217

Chapter 17
6RD Configuration
Table of Contents
6RD Overview ..........................................................................................................17-1
Configuring 6RD Tunnels .........................................................................................17-5
6RD Configuration Example .....................................................................................17-6
17.1 6RD Overview
Introduction
6rd specifies a protocol mechanism to deploy IPv6 to sites through a service provider's
(SP's) IPv4 network. It builds on 6to4, with the key differentiator that it utilizes an SP's own
IPv6 address prefix rather than a well-known prefix (2002::/16). By using the SP's IPv6
prefix, the operational domain of 6rd is limited to the SP network, and is under its direct
control. From the perspective of customer sites and the IPv6 Internet at large, the IPv6
service provided is equivalent to native IPv6.
The 6rd mechanism relies upon an algorithmic mapping between the IPv6 and IPv4
addresses that are assigned for use within the SP network. This mapping allows for
automatic determination of IPv4 tunnel endpoints from IPv6 prefixes, allowing stateless
operation of 6rd.
A 6rd domain consists of 6rd Customer Edge (CE) routers and one or more 6rd Border
Relays (BRs). IPv6 packets encapsulated by 6rd follow the IPv4 routing topology within
the SP network among CEs and BRs. 6rd BRs are traversed only for IPv6 packets that
are destined to or are arriving from outside the SP's 6rd domain. As 6rd is stateless, BRs
may be reached using anycast for failover and resiliency.
6rd utilizes the same encapsulation and base mechanism as 6to4, and could be viewed as
a superset of 6to4 (6to4 could be achieved by setting the 6rd prefix to 2002::/16). Unlike
6to4, 6rd is for use only in an environment where a service provider closely manages the
delivery of IPv6 service. 6to4 routes with the 2002::/16 prefix may exist alongside 6rd in
the 6rd CE router, and doing so may offer some efficiencies when communicating directly
with 6to4 routers.
6rd Prefix Delegation
Figure 17-1 shows the format of an IPv6 address with a 6rd prefix and an embedded CE
IPv4 address.
17-1
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