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MPLS for Traffic Management

MPLS for Traffic Management

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    S.t rajan cjb0912010 ft12 S.t rajan cjb0912010 ft12 Presentation Transcript

    • Presentation MPLS FOR TRAFFIC MANAGEMENT S.T.RAJAN CJB0912010, FT12 M. Sc. (Engg.) in Computer Science & NetworkingModule Leader : Narasimha Murthy K.R M.S.Ramaiah School of Advanced Studies 1
    • Session Topics• Convention IP Datagram & ATM• MPLS by Definition• Traffic Management• Terminology & Components• Primary Protocols for Qos & Cos• Working Mechanism• Implementation• Deployment Strategy• Summary M.S.Ramaiah School of Advanced Studies 2
    • Conventional IP Networks &ATMIP Routing Disadvantages:•It is based on connectionless so no QOS.• Each router has to make independent forwarding decisions based on the IP- address.• Large IP Header - At least 20 bytes• Routing in Network Layer - Slower than Switching• Usually designed to obtain shortest path- Do not take into account additional metrics .where it was not competent Overall it is Based on the Metric Optimisation .so the link constraints not taken into consideration.ATM Principle :.• It overlays network solution.– fast packet switching with fixed length packets (cells)– integration of different traffic types (voice, data, video)Drawbacks Of ATM:• Not well integrated for engineering traffic flows• Wastage of bandwidth .• Complex & Expensive. M.S.Ramaiah School of Advanced Studies 3
    • Evolution of MPLSIt stands for “Multi Protocol Label Switching”. Control: Control: Control: ATM Forum IP Router Software Software IP Router Software Forwarding: Forwarding: Forwarding: Longest-match Lookup Label Swapping Label Swapping• Figures Represent protocol used in layer 2 & 3 in TCP/IP Stack M.S.Ramaiah School of Advanced Studies 4
    • Need for MPLSMPLS Functions•Uses Control-driven model.•MPLS simplifies forwarding function by taking a totally differentapproach by introducing a connection oriented mechanism inside theconnectionless IP networks•Initially Designed for Enhancing Look up Speed for Routers butessentially used for traffic engineering.• IETF creates MPLS working group to create unified standard (FrameRelay, PPP, SONET), not just ATM.MPLS Characteristics – Mechanisms to manage traffic flows of various granularities (Flow Management) by using single forwarding algorithm . – Is independent of Layer-2 and Layer-3 protocols – Maps IP-addresses to fixed length labels – Interfaces to existing routing protocols (RSVP, OSPF)&futuristic M.S.Ramaiah School of Advanced Studies 5
    • MPLS-TE Example• Buses run with Route Number which is indication of route from start point .• Similarly in MPLS each LSR will label the packets with the route label or swaps label and sends to the end Router• Traffic management is done by signaling protocol with dedicated path called Trunk Tunneling . LSP Trunk Tunneling Router B Router B M.S.Ramaiah School of Advanced Studies 6
    • Need For Traffic ManagementTraffic Management•The task of mapping traffic flows onto an existing physicaltopology to facilitate efficient and reliable network operations• traffic oriented e.g. minimization of packet loss•resource oriented - optimization of resource utilization e.g.efficient management of bandwidthPerformance Objective Minimizing congestion is a major traffic and resource oriented performance objective Congestion manifest under two scenarios -network resources are insufficient or inadequate can be solved by capacity expansion or classical congestion control techniques -traffic streams are inefficiently mapped onto available resources can be reduced by adopting load balancing policies M.S.Ramaiah School of Advanced Studies 7
    • Advantages of TM & Working• Variously divisible traffic aggregation and disaggregation Maneuvering load distribution• Stand-by secondary paths and precomputed detouring paths Strongly unified measurement and control for each “traffic- engineered path” Explanation :If network core runs conventional longest-match IP forwarding: –Data from Host A and B follow path 1 since it is the shortest-path computed. –With MPLS, network administrator could split traffic: •Host A traffic over path 1 & Host B traffic over path 2 M.S.Ramaiah School of Advanced Studies 8
    • Terminology• FEC (Forwarding Equivalence Class)-Group of packets sharing the same type of transport.• LSR (Label Switched Router)-Swaps labels on packets in core of network.• LER (Label Edge Router)-Attach Labels to packets based on a FEC.• LSP (Label Switch Path)-Path through network based on a FEC (simplex in nature). The “traffic-engineered path”• LIB (Label Information Base)- MPLS equivalent to IP routing table, contains FEC-to-Label bindings• Traffic Trunk (TT) -Traffic Trunk - aggregation of traffic flows of the same class which are placed inside a Label Switched Path -forwarded through a common path with common TE requirements characterized by its ingress and egress M.S.Ramaiah School of Advanced Studies 9
    • Positions In MPLSLER (Label Edge Router ) or Penultimate RouterLSR (Label Switch Router) or Transit RouterLSP:Label Switch PathMumbai is Ingress Router & Kolkata is Egress Router Mumbai Kolkata Pune Secunderbad Vijayawada Bhuvaneshwar M.S.Ramaiah School of Advanced Studies 10
    • LSP & GraphsMPLS provides two options to set up an LSP • Hop-by-hop routing -Each LSR independently selects the next hop for a given FEC. LSRs support any available routing protocols (OSPF, ATM …). • Explicit routing -Is similar to source routing. The ingress LSR specifies the list of nodes through which the packet traverses.The LSP setup for an FEC is unidirectional. The return trafficmust take another LSP!.Two types Static or dynamic.Induced MPLS Graph•analogous to a virtual topology in an overlay model•logically mapped onto the physical network through the selectionso LSPs for traffic trunk•comprises a set of LSRs which act as nodes of the graph and a setof LSPs which provide logical point to point connectivity betweenLSRs and thus act as edges of the graph Advanced Studies M.S.Ramaiah School of 11
    • Components MPLS-TE• Packet Forwarding Component MPLS, label switching itself• Information Distribution Component IGP (OSPF/IS-IS) extension• Path Selection Component Constrained Shortest Path First (CSPF) algorithm or BGP• Signaling Component LDP, CR-LDP, and RSVP-TE -In MPLS, traffic engineering is inherently provided using explicitly routed paths.• The LSPs are created independently, specifying different paths that are based on user-defined policies. However, this may require extensive operator intervention.• RSVP-TE and LDP are two possible approaches to supply dynamic traffic engineering and QoS in MPLS. M.S.Ramaiah School of Advanced Studies 12
    • Dynamic LSP using RSVP• Dynamic LSP Created without user intervention• User control used by two protocol RSVP or LDPRSVP (Resource Reservation Protocol)• Signaling Protocol designed by IETF• Application to request & reserves resources hop by hop• Request bandwidth and traffic conditions on a defined path.• Using “Path” message from source to destination• Reply message “Resv” From destination to source by updating “softstate”which is database for reservation .• Establishes the LSP.• LSP is operation as long as soft state• QOS and COS• The generic protocol is extension of MPLS implementation R8 R3 R4 R2Setup: Path (R2->R6->R7->R4) R5 PopLabels Established on Resv R1 R6 R7message M.S.Ramaiah School of Advanced Studies 13 22
    • LDPLabel Distribution Protocol designed specifically for MPLSFour message classes1. Discovery-Announce and maintain presence of an LSR.2. Session-establish, maintain, terminate sessions b/w LDP peers.3. Advertisement-create, change, delete label mappings.4. Notification-advisory and error info. •Discovery: Runs over UDPMulticast’s “Hello” •All others run over TCPmessage is by LSR M.S.Ramaiah School of Advanced Studies 14
    • CBR-LDP • Enables a demand driven, resource reservation aware, routing paradigm to co-exist with current topology driven protocols uses the following inputs traffic trunk attributes resource attributes other topology state information • Basic features prune the resources that do not meet the requirements of the traffic trunk attribute run a shortest path algorithm on the residual graphAdvantages of traffic trunks•No. of trunks dependent only on the topology•Forwarding table does not grow with the traffic•Rerouting RSVP, CR-LDP, or IGP M.S.Ramaiah School of Advanced Studies 15
    • Working Mechanism -TESteps For TE Establishment• LSP Tunnels which are Signaled to RSVP which are unidirectional•Link State IGP for global flooding of resource Information & automaticrouting of traffic .•MPLS traffic engineering module for path calculation which path to beused LSP tunnel.•Link Management Module link admission and book keeping of resourceinformation to be flooded•Label Switching Forwarding based on Resource based RoutingAlgorithmMapping into Tunnel•IGP uses Dijkstras shortest path first (SPF) algorithm. Routing Tables are Derived from Shortest Path Tree.•Another Algorithm calculates explicit route from one or more nodesbased on LSP and TE Tunnels M.S.Ramaiah School of Advanced Studies 16
    • SFP ComputationDetermination of first Hop Information•When Path is found for new node it moves new node from tentative listto path lists•Based on TE Tunnel the tail end is First Hop Information updated•Without TE Tunnel the uses First Hop Information from adjacent ofjust connected node.•When both Cases fail ,it copies the information from parent node to newnode.AdvantagesIf there is more than one TE tunnel to different intermediate nodes on thepath to destinationnode X, traffic flows over the TE tunnel whose tailend node is closest tonode X. M.S.Ramaiah School of Advanced Studies 17
    • TE-Tunneling Mesh Network R-B R-CR-A R-D R-EAssumeTunnelingpresent from Ato D and Samecost Network.Then SFPimplements to The diagram shows Mesh Topology with dedicateddo load sharing trunks M.S.Ramaiah School of Advanced Studies 18
    • Signaling Protocols•Implicit routing- labels are set-up and torn-down (like telephone calls), also known as hard state.•Explicit routing- allows for better traffic engineering, traffic tunnels are created based on overall view of topology. More dynamic.  Protocol Routing Traffic engineering      LDP Implicit NO      BGP Implicit NO      IS-IS Implicit NO      CR-LPD Explicit YES      RSVP-TE Explicit YES      OSPF- Explicit YES TE M.S.Ramaiah School of Advanced Studies 19
    • Implementation Consideration Management Interface Constraint Based ConventionalMPLS Routing Process IGP Process Resource Attribute Link State Availability Database Database M.S.Ramaiah School of Advanced Studies 20
    • Deployment Strategy-1Congestion Free Network : 1) Configure your IGP, RSVP 2) Configure TE tunnels around congested links - one IGP tunnel, one or more explicit-path tunnels. 3) Turn up tunnels one at a time via ‘autoroute announce’ 4) Add BW requirements to tunnels Tunnel BW ratio is important. Link Protection:Step1: link failure detection O(depends on L2/L1)Step2: IGP reaction (ISIS case) Either via Step1 or via IGP hello expiration (30s by default for ISIS) .5s (default) must occur by default before the generation of a new LSPStep3: RSVP signalization M.S.Ramaiah School of Advanced Studies 21
    • Deployment Strategy-2Step4: Either stepA or stepB alarms the head-endStep35: Re-optimization dijkstra computation: O(0.5)ms per node (rule of thumb) RSVP signalisation time to install re-routed tunnel⇒convergence in the order of several seconds (at least).⇒This includes fast switch over into secondary TE tunnel Path. Backup Tunnel to the next-hop of the LSPs next-hopR3 R4 R2 R1 R5 R7 R6 M.S.Ramaiah School of Advanced Studies 22
    • MPLS-TE Deployment IssuesMPLS is proposed as a standard TE solution by IETF, BUT • Vendor Interoperability problem • Limitation in online path calculation • Problems on Traffic Trunks • Measurement and Control Issues M.S.Ramaiah School of Advanced Studies 23
    • SummaryBased On MPLS•Improves packet-forwarding performance in the network•Supports QoS and CoS for service differentiation•Supports network scalability•Integrates IP and ATM in the network•Builds interoperable networksBased on MPLS TE:•MPLS supports tunneling, which breaks the transparency paradigm.•MPLS supports sessions, it breaks the datagram model.•TE Done by SFP based on different Protocols.•Higher return on network backbone infrastructure investment.•Reduction in operating costs•To increase the resource utilization MPLS Traffic Engineering•To speed up convergence upon link or node failure MPLS TE and Link/Node protection•To ease capacity planning -Aggregate Admission Control M.S.Ramaiah School of Advanced Studies 24
    • References• Sreekanth P V, Digital Transmission Hierarchies, Universities Press ,2010,p209-225.• Ramaswami .R and Sivarajan. K. N. , Optical Networks: A Practical Perspective ,Morgan Kaufmann Publishers, 2nd .• Cisco IOS Release 11.3 Network Protocols Configuration Guide, Part 1, “Multiple Label Switching Traffic” chapter. M.S.Ramaiah School of Advanced Studies 25
    • Thank YouM.S.Ramaiah School of Advanced Studies 26