6PE

What Is 6PE? What Problems Does 6PE Solve?

IPv6 Provider Edge (6PE) is a transitional technology designed to enable the coexistence and intercommunication of IPv4 and IPv6 networks by leveraging Multiprotocol Label Switching (MPLS). This solution allows separate IPv6 domains to interconnect through MPLS Label Switched Paths (LSPs) over an established IPv4 MPLS core infrastructure. It optimizes the use of existing MPLS network capacities while preserving current services uninterrupted.

Why Do We Need 6PE?

6PE, which stands for IPv6 Provider Edge, is a transitional solution that addresses the need to support IPv6 over existing IPv4 infrastructures, particularly when those infrastructures leverage MPLS (Multiprotocol Label Switching) technology. As the internet continues to grow, the adoption of IPv6 becomes increasingly essential due to the exhaustion of IPv4 addresses. Here are the reasons why 6PE is vital for network evolution:

IPv6 Network Islands

As IPv6 networks began to proliferate, they often existed as small "islands" within the vast "sea" of the established IPv4 networks. 6PE allows these islands to connect and communicate over the IPv4 MPLS backbone, ensuring seamless integration and service continuity.

Smooth Transition

When it comes to transforming an existing IPv4 network to support IPv6, simplicity, cost-effectiveness, and minimal service disruption are key considerations. 6PE offers a smooth evolution path that maintains the operational integrity of the IPv4 services during the transition phase.

Lack of Mature IPv6 Label Distribution

In MPLS networks, there is no well-established protocol for distributing IPv6 labels. This makes direct label assignment to IPv6 prefixes challenging for data forwarding purposes. 6PE emerges as a transitional solution to bridge this gap by employing the existing MPLS infrastructure.

Service Interworking

6PE allows different network protocols to coexist and interoperate, ensuring that diverse services can function seamlessly across various network domains. This is particularly handy in scenarios where metro networks extend across multiple Autonomous Systems (ASs) during 6PE deployment.

The benefits of 6PE include:

• Ease of Maintenance: Configuration efforts are confined to the Provider Edge routers that interface with customer endpoints, leaving the core IPv6 network uninvolved with the inner workings of the IPv4 network. This simplifies network management and supports staged network upgrades.

• Cost-Efficiency in Network Expansion: By utilizing the already-established IPv4 MPLS tunnels, 6PE allows network providers to offer IPv6 services without significant infrastructural modifications or upgrades. It also enables the concurrent provision of multiple service types, including both IPv6 and IPv4 VPNs, thereby making the most of current network investments.

What Types of 6PE Exist?

6PE, which facilitates IPv6 connectivity over an existing IPv4 backbone using Multiprotocol Label Switching (MPLS), has variations that depend on the network architecture—particularly, the scope of Autonomous Systems (ASs) it spans. There are two primary categories of 6PE deployment: intra-AS 6PE and inter-AS 6PE. The latter can be further divided into Option B and Option C. These types are distinguished by the way they handle IPv6 routing information and MPLS label distribution across different ASs.

Overview of 6PE Networking Types

Intra-AS 6PE:

• Utilized within a single AS to interconnect disparate IPv6 networks.

• Provider Edge (PE) routers within the AS establish MP-IBGP (Multiprotocol Internal BGP) sessions to exchange IPv6 routing information.

• Network devices include provider (P) routers, which form the MPLS backbone, PE routers at the network edge, and customer edge (CE) routers, which can be host devices not necessarily supporting MPLS.

• PE routers assign MPLS labels to IPv6 packets, employing an inner label for the IPv6 prefix and an outer label for the LSP (Label Switched Path) between 6PE routers.

• IPv6 traffic traverses the IPv4 MPLS core network based on these MPLS labels.

Inter-AS 6PE Option B:

• Deployed when separate IPv6 networks are connected across multiple ASs.

• AS boundary routers (ASBRs) can also serve as PEs, exchanging IPv6 routes using MP-EBGP (Multiprotocol External BGP).

• In cases where ASBRs are not PEs, IPv4 routing protocols handle the labeled route exchange between PEs and ASBRs, and tunnels are established to facilitate the transparent transfer of IPv6 packets between ASBRs and PEs within the same AS.

Inter-AS 6PE Option C:

• In this setup, a PE establishes a multi-hop MP-EBGP session with a remote PE across ASs and exchanges labeled routes using an IPv4 routing protocol.

• IPv6 packets are transparently conveyed between PEs over end-to-end BGP LSPs.

Each flavor of 6PE networking is tailored to specific operational environments and considerations. For instance, intra-AS 6PE is preferred when all 6PE routers reside within a single AS, simplifying label distribution and route management. On the other hand, inter-AS options provide means to extend 6PE connectivity between distinct ASs, addressing scenarios such as those encountered in collaborative carrier backbone networks or wide-reaching metro networks. These solutions balance the need for IPv6 interoperability with the scalability and administrative constraints of MPLS-based carrier networks.

What Are the Differences Between 6PE and 6VPE?

6PE and 6VPE are technologies designed to support IPv6 traffic over an IPv4 MPLS backbone, but they cater to different networking needs and scenarios. To understand their differences, it's essential to consider the level of isolation and the type of services they provide.

6PE (IPv6 Provider Edge) is designed to connect IPv6 networks over an MPLS IPv4 network without providing any virtual private networking capabilities. Consequently, all the IPv6 networks connected via 6PE are part of the same virtual network and cannot be logically segregated. This solution is suitable for open IPv6 networks that do not require protection or logical separation from one another.

In contrast, 6VPE (IPv6 VPN Provider Edge) builds on the concept of 6PE by adding support for logical isolation through the implementation of VPNs. 6VPE is used when privacy and isolation are required for multiple IPv6 networks over a shared IPv4 MPLS backbone. It provides each customer with its own "virtual" network, ensuring that the IPv6 services of different users remain isolated. This is achieved using VPN-IPv6 address families and VRF-IPv6 (Virtual Routing and Forwarding for IPv6), which enhance the security of the connected IPv6 networks by keeping them logically separated.

The core difference between 6PE and 6VPE lies in their approach to privacy and network segmentation:

• 6PE essentially extends the IPv6 network over the MPLS IPv4 core, treating all IPv6 traffic as a part of a single network, which is perfect for scenarios where logical separation is not necessary.

• 6VPE, on the other hand, creates isolated VPN instances for different IPv6 networks, providing enhanced security and enabling the delivery of private network services over the public or backbone IPv4 MPLS network.

6VPE makes use of L3VPN concepts to establish distinct IPv6 VPNs. While a conventional MPLS L3VPN may only support IPv4 traffic, with a dual-stack implementation, it's possible for the VPN to handle both IPv4 and IPv6 traffic simultaneously, allowing for a more versatile and future-proof networking solution within an MPLS framework.