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IMPLEMENTATION GUIDE -6rd Configuration Guide
1 Introduction
ISPs today have to address the problem of IPv4 address exhaustion and in parallel enable IPv6 services over
IPv4 infrastructure. IPv6 and IPv4 are expected to coexist for a long time to come. Providers are looking at mixed
approaches, from enabling IPv6 services in the least disruptive ways on legacy infrastructure to deploying IPv6 from
the get-go in greenfield applications. 6rd is one mechanism to start offering IPv6 services over IPv4 infrastructure.
2 Scope
This implementation guide provides an overview of 6rd with configuration steps and basic design guidelines when
implementing 6rd with the Service-PIC or MS-DPC blade on the Juniper Networks
routers. This guide also covers some operational aspects and coexistence of other IPv6 transition mechanisms such as
DS-Lite. for an in-depth look at IPv6 transition mechanisms and methods to address IPv4 address exhaustion, please
refer to http://www.juniper.net/ipv6.
3 Design Considerations
IPv6 rapid deployment (6rd) enables ISPs to deploy IPv6 unicast service to IPv4 sites rapidly. It allows ISPs to reuse
the existing IPv4 access network infrastructure and provide connectivity to islands of v6 networks. The IPv6 packets
from a host (laptop/PC) are carried in IPv6-in-IPv4 tunnels from the 6rd customer edge (CE) routers to the 6rd Border
relay(s) (Br). These IPv6-in-IPv4 tunnels are called softwires [RFC4925] and terminate on the Br, also called softwire
concentrator (SC), at some point in the network where IPv6 packets are decapsulated and forwarded. 6rd builds on
6to4 tunneling concepts and overcomes some of its limitations. The key difference with 6to4 is that 6rd addresses
are derived from an IPv6 prefix tied to the service provider address space, guaranteeing return reachability of the IPv6
packets. IPv6 packets are tunneled in IPv4 with stateless v6 to v4 mapping and automatic prefix delegation derived
from the v6 destination of each packet. The key component changes are to the routed CPE to make it 6rd capable, via
software or hardware upgrade and introduction of a 6rd Border relay function in the ISP network to route the packets
to IPv6 networks.
Juniper Networks M Series Multiservice Edge routers/T Series Core routers/MX Series 3D Universal Edge routers can
play the role of Br.
4 Terminology
• 6rd prefix: This is an IPv6 prefix selected by the service provider for use by a 6rd domain. There is exactly one 6rd
prefix for a given 6rd domain. An SP can deploy 6rd with a single 6rd domain or multiple 6rd domains.
• 6rd Customer Edge (6rd CE): This device functions as a CE router in a 6rd deployment, which is also called
residential gateway (rG) or customer premises equipment(CPE).
• 6rd domain: A set of 6rd CEs and Brs is connected to the same virtual 6rd link. A service provider can deploy 6rd
with a single domain or multiple 6rd domains based on geographic or operational boundaries. Each domain requires
a separate 6rd prefix.
• CE LAN side: The functionality of a 6rd CE device serves the "customer-facing" side of the CE device. The CE LAN-
side interface is fully IPv6 enabled.
• CE WAN side: The functionality of a 6rd CE device serves the "service provider-facing" side of the CE device. The CE
WAN side is IPv4-only.
• 6rd Border relay: A 6rd-enabled router is at the edge of a 6rd domain.
• Br IPv4 address: This is the IPv4 address of the 6rd Border relay for a given 6rd domain. The CE device uses this
IPv4 address to send packets to the Br in order to reach IPv6 destinations outside of the 6rd domain.
• CE IPv4 address: This is the IPv4 address given to the CE device as part of normal IPv4 Internet access (that is,
configured via DHCP, PPP, or otherwise). This address can be global or private [rfC1918] within the 6rd domain.
• S-PIC/Service DPC: This refers to services PIC or Services DPC on the Br router where IP6in-IPv4 where the softwire
is created.
4
MX Series 3D Universal Edge
®
Copyright © 2011, Juniper Networks, Inc.
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