Switching systems lecture8 mpls
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This document provides an overview of MPLS (Multi-Protocol Label Switching) including: 1) It describes the need for MPLS arising from limitations in traditional IP forwarding and issues running one statmux technology over another. 2) It explains basic MPLS concepts like label switching, label distribution protocols, label edge and switch routers, label switching paths, and forwarding equivalence classes. 3) It outlines the basic working process of MPLS including label encapsulation, lookup, and processing functions like push, pop and swap.
Switching systems lecture8 mpls
- 1. DIT Dar es Salaam institute of Technology (DIT) ETU 07420 Switching Systems Ally, J jumannea@gmail.com
- 3. DIT MPLS Contents Data networking and need for MPLS Basic concepts and working of MPLS Label - Allocation and Distribution MPLS Forwarding
- 5. Data Network Concept A data network is a set of nodes connected by links. Nodes could be Routers, Switches, Multiplexers connected by links from 64 kbps till 10 gigabit ethernet. Fundamental property of data networks is multiplexing. Two main types of multiplexing are - Time Division Multiplexing ( TDM ) Statistical Multiplexing ( StatMux) Others are FDM , WDM etc. DIT
- 6. Data Network Concept TDM is practice of allocating certain amount of time on a physical circuit for a particular connection. This translates to bandwidth allocation as the circuits are fixed rate. Examples for TDM being E1 (2Mbps circuit) , SDH Bandwidth permanently allocated for a connection whether connection used ( carrying traffic) or not. No traffic congestion issues, bandwidth guaranteed DIT
- 7. Data Network Concept Statmux - is the practice of sharing available bandwidth between all users. Examples are : IP , Frame Relay, ATM & now MPLS. It works by way of dividing traffic (data) into discrete units which are handled separately. IP units are Packets, ATM units are Cells, Frame Relay units are Frames. Better utilisation of bandwidth, allows oversubscription. DIT
- 8. Data Network Concept Introduces resource contention. Therefore statmux technologies have to deal with Buffering of data units Queuing of data units Dropping of data units Running one statmux technology over other eg. IP over ATM . Mechanisms available in one technology to deal with contention does not translate properly into another. Requirement of translating Layer 3 contention controls mechanisms to Layer 2. DIT
- 15. MPLS Origin DIT
- 16. MPLS Origin To bring advantages of connection oriented protocols to packet switched networks. Faster switching - Replace IP header with short and fixed-length labels as forwarding basis. To substitute ATM & Frame Relay & provide Integrated services with QoS without the overhead of call segmentation. DIT
- 17. MPLS Origin Technology combining the advantages of ATM and IP Layer 3 routing – Scalable and Flexible Layer 2 switching – Reliable and Traffic Engineering capability MPLS - Multi-Protocol Label Switching DIT
- 19. MPLS MPLS is the binding of the control plane at the bottom of the network layer with the data forwarding plane at the top of data link layer. MPLS is a hybrid of a traditional network layer-3 routing protocols and layer-2 switching technologies MPLS is not a new network layer protocol because it does not have its own routing capabilities and addressing schemes MPLS is designed to work over many of the data layer technologies that provides requisite layer-2 addressing and functionality MPLS is a “Layer 2.5 Technology” DIT
- 21. Label Position in Packet DIT
- 22. Basic Working Process of MPLS DIT
- 23. MPLS Label DIT
- 24. MPLS Devices MPLS uses Label Switched Path (LSP) for layer-2 forwarding. The path is setup using signaling protocols like Label Distribution Protocol (LDP) and routing protocols. DIT
- 25. MPLS Terminology LER -Label Edge Router Examines inbound IP packets and assigns them to an FEC Generates MPLS header and assigns initial label i.e Ingress & Egress LSR - Label Switch Router Forwards MPLS packets using Label swapping Table lookup in Label Information Base (LIB) LSP - Label Switch Path Path thro’ MPLS network setup by signaling protocol (LDP) LSP’s are unidirectional , roughly equivalent to VC LSP setup is based on FEC criteria LSP may be different from IGP path DIT
- 26. MPLS Terminology Forwarding Equivalence Class (FEC) is a stream of IP packets that are forwarded over the same path, treated in the same manner and mapped to the same label. ( Same QoS ; Same Next Hop; Same Path) LDP ( Label Distribution Protocol) associates a set of destinations with each LSP Packets could be assigned to a LSP based on Combination of destination address and application type Combination of destination address and source address DIT
- 27. Label Processing Push Add a new label to the top of the packet The TTL, stack and CoS fields are derived from the IP packet header Can be performed on an existing MPLS packet-Label Stacking Pop Remove the label TTL is copied from the label to the IP header IP packet is forwarded as a native IP packet Swap Replace the label at the top of the label stack with a new label The TTL, stack and CoS fields are copied from the previous label DIT
- 28. MTNL MPLS Network - Mumbai DIT
- 29. DIT Thanks! Technology changes but communication lasts.