IP-MPLS Theory PDF

IP-MPLS Introduction - Multiprotocol label switching (MPLS), also known as IP-MPLS, is a routing mechanism in telecommunication networks - Routers direct data based on short path labels instead of longer network addresses - This speeds up communications, avoids complex routing table...

IP-MPLS Introduction - Multiprotocol label switching (MPLS), also known as IP-MPLS, is a routing mechanism in telecommunication networks - Routers direct data based on short path labels instead of longer network addresses - This speeds up communications, avoids complex routing table lookups - Encapsulates diverse protocols into packets with its own protocol, hence \"multiprotocol\" MPLS Framework - An Internet Engineering Task Force (IETF) specified framework - Provides efficient forwarding, routing, and switching of network traffic - Designed to overcome limitations of traditional IP-based VPN forwarding MPLS Packet Forwarding - MPLS forwarding decisions are based solely on packet labels, eliminating the need to examine the entire packet - Simplifies and speeds up forwarding compared to traditional IP-based methods - Considered Layer 2.5 networking protocol, functioning between OSI data link and network layers IP-MPLS as Transport Technology for Railways - Chosen as future transport technology for Indian Railways - Supports L2 and L3 services, essential for railway network requirements - Allows common network management system (NMS) for all network components (core, aggregation, access) - Supports IP routing and network-oriented connections - Uses hardware-based forwarding, which is faster than conventional routing - Unidirectional paths with separate forward and return paths; bidirectional paths for transport requirements - Software-defined WAN (SD-WAN) with IP-MPLS decouples network hardware from control mechanisms Technology & Terminology - MPLS itself is not a specific technology, but an overlay technique for performance improvement - FEC (Forwarding Equivalence Class) value is assigned to a packet when it enters the MPLS network - Small labels are added to packets, used as an index by routers for quick forwarding decisions MPLS Header Structure - 32-bit header - 20 bits dedicated to the label or label stack - 3 experimental bits (for specifying class of service) - 1 reserved bit (for the bottom of the label stack) - 8 bits for Time-to-Live (TTL) similar to IP headers Label Forwarding Information Base (LFIB) - Table created by label switch-capable devices - Indicates forwarding destinations for specific label values Label Switched Path (LSP) - Unidirectional tunnel between routers in the MPLS network Label Edge Router/Ingress Router (LER) - Router encapsulating packets into MPLS LSPs - Initiates path selection for packets Label Switched Router (LSR) - Performs MPLS switching within an LSP - Makes forwarding decisions based on label presence Egress Router - Removes the label from a packet at the end of the LSP Label Switch Controller (LSC) - LSR that communicates with ATM switches for label information Label Distribution Protocol (LDP) - Primary protocol for distributing labels in MPLS networks - Establishes Label Switched Paths (LSPs) by mapping between network and data link layer information - Enables hop-by-hop packet delivery in the MPLS network Forwarding Equivalence Class (FEC) - Group of IP packets with identical forwarding requirements - The same destination, path, and service class MPLS Operation - Relies on two components: Control Plane and Data Plane - Control Plane: Manages label-to-network route binding using protocols like OSPF, IS-IS, and BGP to exchange information between routers - Data Plane: Responsible for forwarding packets according to labels and destinations, independent of the routing protocol MPLS Services - MPLS Traffic Engineering (TE): Optimizes network traffic flows and balances traffic loads across various routes. - Quality of Service (QoS): Enables prioritization of different traffic types - Virtual Private Networks (VPNs): Securely connect multiple sites over a single network, offering equivalent privacy as frame relay, but with more operational efficiency. MPLS Advantages and Disadvantages - **Advantages** - Scalability - Enhanced bandwidth - Improved uptime - Lower congestion - Remote connections (reduced hardware needs) - Quality of Service options - WAN protocol (supports diverse connectivity) - **Disadvantages** - Lack of complete control - Could be more expensive than some other network technologies Implementation Considerations for Indian Railways - Centralized data communication circuits - Data services and applications (e.g., UTS/FOIS, VoIP) - Service server locations (ideally within Divisional HQs) - Future equipment replacement with MPLS - Training needs on new technologies - NOC (Network Operations Center) needs Backup and Troubleshooting Capabilities of NOC - Patch management, backup management, troubleshooting, field support - Service provisioning, performance reporting and recommendations