Voice over MPLS


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Voice over MPLS

  1. 1. Voice over MPLS (Voice over Multi Protocol Label Switching) Tooba Zaheer Shaikh BS IV B
  2. 2. PSTN – The old way <ul><li>PSTN – Public Switched Telephone Network </li></ul><ul><li>Analog switched device </li></ul><ul><li>Circuit Switched Mechanism </li></ul><ul><li>Resources are reserved for the call </li></ul><ul><li>Waste of resources as 60% of the time there is no data flow. </li></ul><ul><li>DS-0 (digital signal used to connect calls) </li></ul><ul><li>Greatest disadvantage is wastage of resources. </li></ul>
  3. 3. Public Switched Telephone Network
  4. 4. Introduction <ul><li>Internetworking refers to the situation where a number of networks are connected. </li></ul><ul><li>The Internet refers to the world wide interconnected group of computers all connected to each other. </li></ul><ul><li>Communication between these computers (hosts) is carried on the basis of a globally agreed way of identifying the destination – the IP. </li></ul><ul><li>IPv4 uses 32 bit fields to identify the destination and the source. </li></ul><ul><li>This address (IP) is globally significant. </li></ul><ul><li>IP forwarding is a connection less operation. </li></ul>
  5. 6. VoIP <ul><li>VoIP- Voice over Internet Protocol </li></ul><ul><li>A set of facilities for managing the delivery of voice information through internet protocol. </li></ul><ul><li>Also called Internet Telephony, IP Telephony or Voice over the Internet (VOI) </li></ul>
  6. 7. Why VoIP <ul><li>Allows a single network infrastructure to carry both voice and data. </li></ul><ul><li>More efficient than circuit switched networks. </li></ul><ul><li>Requires small investment in network infrastructure to carry given amount of traffic. </li></ul><ul><li>Supports private voice networks. </li></ul>
  7. 8. Benefits of VoIP <ul><li>Cost Saving </li></ul><ul><li>Open Standards and multivendor interoperability </li></ul><ul><li>Integrated Voice and Data Networks </li></ul>
  8. 9. Transmission of voice using VoIP <ul><li>Digitizing voice </li></ul><ul><li>Packetizing digitized voice </li></ul><ul><li>Error detection and correction </li></ul><ul><li>Assembling and decompressing to restore voice. </li></ul>
  9. 10. High Level Packet Voice Transmission
  10. 11. Functions of VoIP <ul><li>Signaling </li></ul><ul><li>Database Services </li></ul><ul><li>Call connect and disconnect </li></ul><ul><li>CODEC Operations </li></ul>
  11. 12. VoIP Components <ul><li>Call Processing Server / IP PBX </li></ul><ul><li>User End Devices </li></ul><ul><li>Media/ VoIP Gateways </li></ul><ul><li>IP Network </li></ul>
  12. 13. VoIP Signaling Protocols <ul><li>H.323 </li></ul><ul><li>Session Initiation Protocol (SIP) </li></ul><ul><li>Real-Time Transport Protocol (RTP) </li></ul><ul><li>Real-Time Transport Control Protocol (RTCP) </li></ul><ul><li>Media Gateway Protocol (MGCP) </li></ul><ul><li>Megaco/H.248 </li></ul>
  13. 14. Considerations for VoIP Network <ul><li>Latency </li></ul><ul><li>Jitter </li></ul><ul><li>Bandwidth </li></ul><ul><li>Packet Loss </li></ul><ul><li>Reliability </li></ul><ul><li>Security </li></ul><ul><li>Interoperability </li></ul>
  14. 15. Problems with VoIP <ul><li>Deciding how to negotiate the parameters and services for a call. </li></ul><ul><li>Getting the voice quality expected from the telephone systems over the network, without long and predictable delays (QoS) . </li></ul>
  15. 16. Requirements for QoS <ul><li>Guarantee a fixed amount of capacity for specific applications, such as audio/video conference </li></ul><ul><li>Control latency and jitter and ensure capacity for voice </li></ul><ul><li>Provide very specific, guaranteed, and quantifiable service-level agreements, or traffic contracts </li></ul><ul><li>Configure varying degrees of QoS for multiple network customers </li></ul>
  16. 17. QoS Deficiencies in IP Networks <ul><li>IP is a connectionless protocol and to have guaranteed QoS in a network, all packets must follow the same path i.e. be connection-oriented. </li></ul><ul><li>Two mechanisms are used </li></ul><ul><ul><li>DiffServ </li></ul></ul><ul><ul><li>RSVP </li></ul></ul>
  17. 18. <ul><li>Demand for greater bandwidth due to the increase in users </li></ul><ul><li>Due to this demand ISPs need high performance switching and routing products. </li></ul><ul><li>Most carriers and service providers run on impressive ATM backbones but the connections to these providers are slow frame relay and point to point connections which introduce latency and sometimes even bottlenecks at the access points. </li></ul><ul><li>Core network routers also add to the latency since forwarding decisions are made individually by the router. </li></ul>
  18. 19. Role of MPLS in the IP core
  19. 20. MPLS <ul><li>MPLS – Multi Protocol Label Switching </li></ul><ul><li>Label switching refers to the technique where units of data are switched through a network by reference to an attached label. </li></ul><ul><li>ATM and Frame relay are Label switched techniques. </li></ul><ul><li>Why MPLS??? </li></ul>
  20. 21. <ul><li>An MPLS network can carry multiple protocols. </li></ul><ul><li>It combines the speed and performance of layer 2 with the scalability and IP intelligence of layer 3. </li></ul><ul><li>MPLS creates a virtual path between the source and the destination. </li></ul>
  21. 22. MPLS Network
  22. 23. LSP <ul><li>LSP – Label switched Path </li></ul><ul><li>An LSP acts like a connection oriented network. </li></ul><ul><li>An LSP is unidirectional </li></ul><ul><li>Reduces network traffic on a single path </li></ul>
  23. 24. LSR/LER <ul><li>LSR – Label Switch Router </li></ul><ul><ul><li>Routers in the core of an MPLS network are label switch routers. </li></ul></ul><ul><li>LER – Label Edge Router </li></ul><ul><ul><li>Routers at the edge of an MPLS network are label edge routers. </li></ul></ul>
  24. 25. Components of an MPLS node <ul><li>Forwarding component (Data Plane) </li></ul><ul><ul><li>Forwards packets based on information from LFIB (Label Forwarding Information Base) </li></ul></ul><ul><li>Control component (Control Plane) </li></ul><ul><ul><li>Manages the LFIB. </li></ul></ul>
  25. 26. MPLS Operation Modes <ul><li>Frame-mode MPLS operation </li></ul><ul><ul><li>3 steps </li></ul></ul><ul><ul><ul><li>Ingress at LER, classification into respective FEC. </li></ul></ul></ul><ul><ul><ul><li>Receiving at LSR </li></ul></ul></ul><ul><ul><ul><li>Egress at LER </li></ul></ul></ul><ul><li>Cell-mode MPLS operation </li></ul><ul><ul><li>Also called MPLS over ATM. </li></ul></ul>
  26. 27. MPLS Label
  27. 28. <ul><li>Label </li></ul><ul><ul><li>Actual 20 bit label. Some values reserve </li></ul></ul><ul><li>CoS </li></ul><ul><ul><li>Class of service </li></ul></ul><ul><li>TTL </li></ul><ul><ul><li>Time to live </li></ul></ul><ul><li>S </li></ul><ul><ul><li>Bottom of stack, 1 for last entry on label stack. </li></ul></ul>
  28. 29. VoMPLS <ul><li>Efficient transport mechanism for voice packets by reducing header overhead. </li></ul><ul><li>Support of efficient multiplexing of multiple voice calls over a single LSP </li></ul><ul><li>Usage of label switched paths as a bearer capability to provide predictable and constrained QoS. </li></ul>
  29. 30. Voice over MPLS <ul><li>3 modes of voice carraige </li></ul><ul><ul><li>MPLS voice type 1 </li></ul></ul><ul><ul><ul><li>voice data is transmitted using H.323 higher-layer encapsulation, including IP, which is then carried in MPLS. </li></ul></ul></ul><ul><ul><ul><li>Disadvantage: greater overhead than is already incurred with the non trivial header sequence of H.323 </li></ul></ul></ul>
  30. 31. <ul><li>MPLS voice type 2 </li></ul><ul><ul><li>H.323 encapsulation is used without IP. The MPLS virtual private network (VPN) tunneling mechanism is used to achieve LSP-based connections. </li></ul></ul><ul><li>MPLS voice type 3 </li></ul><ul><ul><li>very similar to VoATM, where voice bits are carried directly in the MPLS packet. </li></ul></ul><ul><li>Choice of method depends on requirement </li></ul>
  31. 32. Transferring calls over MPLS <ul><li>Multiple calls may be transferred over a single LSP </li></ul><ul><li>Two subframes are related to VoMPLS </li></ul><ul><ul><li>Primary subframe </li></ul></ul><ul><ul><li>Control Subframe </li></ul></ul>
  32. 33. Primary Subframe <ul><li>A primary subframe contains the traffic that is fundamental to the operation of a connection identified by a Channel Identifier (CID). It includes encoded voice and an SID(s). Primary subframes may have variable-length. </li></ul><ul><li>More than one primary subframe may be multiplexed in one frame. </li></ul>
  33. 34. Control Subframe <ul><li>Control subframes may be sent to support the primary payload (such as dialed digits for a primary payload of encoded voice) and other control functions. </li></ul><ul><li>One control subframe in every frame </li></ul><ul><li>Primary and control subframes are multiplexed in one frame. </li></ul>
  34. 35. Conclusion <ul><li>MPLS – A new hope for future </li></ul>