Simplified Seamless MPLS using SRv6

Seamless Multi-Protocol Label Switching (MPLS) Overview:

• Seamless MPLS is a network architecture designed to extend existing MPLS networks by integrating access and aggregation networks into a unified MPLS domain.
• This integration addresses scaling issues commonly encountered in traditional flat MPLS-based deployments.
• Seamless MPLS partitions the core, aggregation, and access networks into isolated IGP/LDP/RSVP/SR/SRv6 domains.
• This partitioning helps to manage network complexity and maintain scalability by isolating different segments of the network.
• Seamless MPLS does not require the development or implementation of new protocols or technologies.
• Instead, it relies on existing, well-established protocols, ensuring a smooth transition and reducing the need for additional resources or training.
• The architecture provides end-to-end, service-independent transport, effectively separating the service and transport planes.
• This separation allows for greater flexibility in managing services and ensures that the transport mechanism remains independent of specific service requirements.

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1) Seamless MPLS using BGP-LU

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Each IGP domain in Seamless MPLS is isolated by its own Interior Gateway Protocol (IGP) and associated labelling protocol.

To achieve end-to-end visibility or reachability across the network, it is necessary to stitch all the separate IGP domains together using BGP-LU .Once the domains are stitched with BGP-LU, end-to-end services can be seamlessly operated across the different IGP domains, ensuring consistent service delivery throughout the network.

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Cons of Seamless MPLS using BGP-LU:

• Heterogeneous Underlay and Overlay Networks: Seamless MPLS can lead to a heterogeneous environment where different underlay and overlay networks coexist. Managing these diverse networks can increase operational complexity and require more sophisticated tools and processes.
• Dependency on BGP-LU for Domain Stitching: Seamless MPLS relies on BGP-LU (Border Gateway Protocol labeled unicast) to stitch together different domains within a Service Provider's network. This reliance adds an extra layer of complexity and can limit scalability, as BGP-LU introduces additional configuration and operational overhead.
• Complexity and Scalability Challenges: The use of BGP-LU significantly increases the overall complexity of the network, potentially leading to challenges in managing and scaling the network efficiently.
• Fast Reroute (FRR) Challenges: Seamless MPLS utilizes LDP (Label Distribution Protocol) with IP Fast Reroute (IP-FRR) or LDP over RSVP (Resource Reservation Protocol) for FRR. While RSVP has its own FRR capabilities, both LDP and RSVP has their own challenges for FRR backup path.

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2)??? Seamless MPLS using SR ( SR-PCE)

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·? Simplified End-to-End Service Provisioning:

• With SR-PCE, the process of provisioning end-to-end services becomes more straightforward.
• SR-PCE enables efficient and automated path computation, reducing the complexity typically associated with manual configuration and ensuring faster service deployment.

·? Automated Network Operations:

• SR-PCE supports automated operations, minimizing the need for manual intervention.
• This automation enhances network efficiency, reduces human errors, and enables dynamic adaptation to changing network conditions.

·? Homogeneous Underlay and Overlay Network:

• SR-PCE helps maintain a homogenous network environment where the underlay and overlay networks are seamlessly integrated.
• This uniformity simplifies network management and ensures consistent performance across the entire network infrastructure.

·? Network Slicing with Flex-Algo:

• SR-PCE enables network slicing using Flex-Algo, allowing for the creation of customized and isolated virtual networks.
• Network slicing supports the allocation of specific resources and policies to different services, ensuring optimal performance and meeting diverse service requirements.

·? Ti-LFA with 100% Coverage and Post-Convergence Path:

• SR-PCE supports Topology Independent Loop-Free Alternate (Ti-LFA) with 100% coverage, ensuring that backup paths are always available.
• The post-convergence path capability ensures that, even after a failure and subsequent network convergence, traffic is efficiently rerouted, maintaining service continuity without disruptions.

·????? No Need for Extra Protocols and Stitching:

• SR-PCE eliminates the need for additional protocols and complex domain stitching within the network.
• This reduction in protocol overhead simplifies the network architecture, making it easier to manage and reducing the potential for configuration errors.

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Cons of Seamless MPLS using SR-PCE:

·? Continued Use of MPLS Labels in the Forwarding Plane:

• Despite advancements in network technologies, MPLS still relies on traditional label-based forwarding in the forwarding plane.
• This reliance on MPLS labels can create limitations in handling the growing demands of modern networks.

·? Limitations in Label Space and Address Space:

• MPLS, originally designed for IPv4 networks, faces constraints in label space and address space.
• These limitations hinder the network's ability to efficiently manage a large number of routes and services, especially as networks scale up.

·? Lack of Summarization Capabilities:

• MPLS does not support route summarization, which is essential for reducing the size of routing tables and improving network efficiency.
• The absence of summarization capabilities can lead to increased complexity and slower convergence in large networks.

·? IPv6 Support Deficiency:

• Traditional MPLS transport technologies are not inherently designed to support IPv6, which is becoming increasingly necessary as IPv4 addresses become exhausted.
• The lack of IPv6 support makes MPLS less suitable for modern network environments that require vast address spaces.

·? Inadequacy for Massive Scale Required by 5G and IoT:

• As 5G and IoT networks continue to expand, the limitations of MPLS become more pronounced, making it less ideal for the massive scale these technologies demand.
• In contrast, SRv6 (Segment Routing over IPv6) provides the scalability and flexibility needed to support the vast number of devices and services in these advanced networks.

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3)??? Seamless MPLS using SRv6

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Locator IDs can be summarized across domains, enabling more efficient routing and reducing the size of routing tables.

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Advantages of SRv6 (Segment Routing over IPv6):

·????? Simplified Network Design:

o?? SRv6 significantly simplifies network architecture by reducing complexity in design and operation.

o?? The streamlined approach allows for easier management and deployment of network services.

·????? Elimination of BGP-LU Shim Layer and Improved Scalability:

o?? SRv6 removes the need for the BGP-LU (Border Gateway Protocol labeled unicast) shim layer, which traditionally adds complexity.

o?? This elimination enhances scalability, especially through the use of summarization, making it easier to manage large-scale networks.

·????? Removal of Legacy Protocols:

o?? SRv6 does away with the need for legacy protocols such as BGP-LU, RSVP-TE (Resource Reservation Protocol-Traffic Engineering), and LDP (Label Distribution Protocol).

o?? By eliminating these protocols, SRv6 simplifies network operations and reduces the overhead associated with maintaining multiple protocols.

·????? Efficient Load Balancing with Flow Labels:

o?? SRv6 enables easy and effective load balancing by using flow labels within the IPv6 header.

o?? This allows for more granular control of traffic distribution across the network.

·????? Native IPv6 Data Plane:

o?? SRv6 operates natively on an IPv6 data plane, fully leveraging the extensive address space and features of IPv6.

o?? This native support ensures future-proofing as IPv6 adoption continues to grow.

·????? Network Slicing with Flex-Algo:

o?? SRv6 supports network slicing through Flex-Algo, enabling the creation of isolated, customized virtual networks.

o?? This allows service providers to allocate specific resources and performance characteristics to different services.

·????? Key Benefit of Summarization:

o?? One of SRv6's major advantages is its ability to perform summarization, even supporting default routes.

o?? This capability greatly reduces the size of routing tables, improving network efficiency and scalability.

·????? Seamless Operation with IPv6-Only Middle Routers:

o?? SRv6 can operate seamlessly even in networks where some middle routers or domains support only IPv6 and not SRv6.

o?? This ensures compatibility and smooth operation across mixed network environments.

·????? Consistency Between RIB and FIB:

o?? With SRv6, there is always consistency between the Routing Information Base (RIB) and the Forwarding Information Base (FIB).

o?? This consistency is maintained because SRv6 operates as a native routing protocol, ensuring accurate and reliable forwarding decisions.

·????? Optimized and Simplified Service Chaining:

o?? SRv6 greatly optimizes and simplifies service chaining, making it easier to implement and manage complex service paths.

o?? This enhances the efficiency and flexibility of service delivery in the network.

·????? Ti-LFA with 100% Coverage and Post-Convergence Path:

o?? SRv6 supports Topology Independent Loop-Free Alternate (Ti-LFA) with 100% coverage, ensuring robust protection against failures.

o?? The post-convergence path capability ensures that, even after a failure and network convergence, traffic is efficiently rerouted, maintaining high availability.

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