Introduction
In the ever-evolving landscape of telecom and computer networks, the coexistence and competition of various network types have given rise to challenges that demand innovative solutions. As the networks expanded to accommodate a growing array of services, complexities emerged, particularly in asynchronous transfer mode (ATM) and IP networks.
While IP networks are comparatively simpler than ATM networks, they still require a certain level of quality of service (QoS) assurance. Additionally, the reliance on table lookups based on the longest match rule in IP networks results in suboptimal forwarding performance. Consequently, the industry sought ways to overcome these obstacles, leading to the development of Multiprotocol Label Switching (MPLS) technology in 1996. MPLS, functioning as a Layer 2.5 technology between Layer 2 and Layer 3, supports multiple network-layer protocols like IPv4 and IPv6 while being compatible with various link-layer technologies such as ATM and Ethernet.
The combination of IP and MPLS has proven effective in delivering QoS assurance in connectionless IP networks, overcoming the forwarding performance limitations of IP networks. However, as networks continue to grow and accommodate emerging services.
Critical problems and challenges of IP-MPLS network
The IP-MPLS combination faces several critical problems and challenges:
- Decreasing Forwarding Advantages: With advancements in routing entry search algorithms and hardware upgrades, MPLS no longer offers significant advantages in forwarding performance compared to IP networks.
- Difficult Cloud-Network Convergence: The rapid expansion of cloud data centers (DCs) to cater to internet and cloud computing advancements necessitates the implementation of overlay technologies like Virtual Extensible Local Area Network (VXLAN). Attempts to integrate MPLS into DCs for VPN services have faced challenges due to network management boundaries, complexity, and scalability.
- Complex Cross-Domain Deployment: MPLS is deployed in different network domains, such as IP backbones, metro, and mobile bearer networks, creating independent MPLS domains and introducing new network boundaries. However, many services require end-to-end (E2E) deployment across multiple MPLS domains, resulting in intricate inter-domain MPLS configuration.
- Challenging Service Management: Coexistence of multiple services, such as L2VPN and L3VPN, leads to the presence of protocols like Label Distribution Protocol (LDP), Resource Reservation Protocol (RSVP), IGP, and BGP on devices. This complexity hampers large-scale service deployment in the 5G and cloud era.
- Complex Protocol States: The exponential growth of states in IGPs and RSVP-TE (Resource Reservation Protocol-Traffic Engineering) puts a strain on transit node performance, making it difficult to construct large-scale networks. RSVP-TE, simulating Synchronous Digital Hierarchy (SDH) pipes, struggles to achieve effective load balancing.
The Impact of Software-Defined Networking (SDN) on Networks
To address the aforementioned issues, the adoption of a centralized architecture and a central control plane node for path computation and label distribution becomes crucial. This is precisely the aspect that Software-Defined Networking (SDN) aims to tackle.
Traditionally represented by OpenFlow, a communication protocol between SDN control and data planes, SDN revolutionizes networks by requiring the upgrade or replacement of all network hardware. However, implementing OpenFlow encounters challenges, including performance bottlenecks and limitations in adapting to complex service deployment. Moreover, OpenFlow necessitates the deployment of new hardware, negating existing investments.
From the information presented, it becomes evident that while OpenFlow suits switch-based networks with simple flow tables and fixed forwarding behaviors, the bearer network requires a technology that can meet SDN’s management and control requirements while providing multi-service support, high performance, and reliability.
Conclusion
By addressing the challenges faced by IP-MPLS networks and recognizing the impact of SDN, we pave the way for a more efficient, adaptive, and resilient network ecosystem. Embracing these advancements enables us to meet the ever-growing demands of the digital era with confidence and innovation.