INTERNET TRAFFIC ENGINEERING USING MPLS & GE N ERAL MULTIPROTOCOL LABEL SWITCHING (GMPLS)

1. INTERNET TRAFFIC ENGINEERING USING MPLS & GENERAL MULTIPROTOCOL LABEL SWITCHING (GMPLS) Presented By: Animut Demeke & Henrik Nårstad

2. CONTENT • Content • MPLS – why? • Advantages with MPLS • A small introduction and some terminology • What can MPLS be used for? • MPLS fundamentals… • General MPLS • Protection and restoration techniques • Summary

3. R8 R3 R4 R5 R2 R1 R6 R7 MULTIPROTOCOL LABEL SWITCHING (MPLS) • How does it work? • Forwards packets based in labels • Why do we need MPLS? • IP uses shortest way routing • Shortest path is not necessarily the only path • Alternative paths are not exploited and the shortest path may be congested

4. ADVANTAGES OF MPLS? • Combines IP-routing and addressing with link layer switching (”Best of both worlds”) • Less overhead • No need to look up IP-addresses in the transit nodes • Better performance (?) • Better control • Supports explicit engineering and paths to support better traffic balancing • MPLS is called multiprotocol because it works with IP, Asynchronous Transfer Mode (ATM), and Frame Relay network protocols • New services • VPN with service quality • Simplified integration with lower layer technologies (ATM, optics)

5. or + = MPLS Router Router Switch MPLE forwarding Principles and operation IP OSI layer 3 MPLS Feth PPP/WDM Feth PPP/WDM Traditional IP forwarding

6. MPLS – a short introduction... 1. Current routing protocols (e.g. OSPF, IS-IS) builds up the IP routing tables 5. Final MPLS-node removes label and forwards based on IP address 2. Protocol for label distrubution establishes mapping between lables and routing tabel entries MPLS-network MPLS-edge node MPLS-node MPLS-edge node MPLS-node MPLS-node MPLS-node 3. First MPLS node (edge node) receives a packet, identifies IP-address, classifies and finally marks the packet with a label 4. MPLS core nodes forwards packets based on the label (these are Router or ATM switch + label Switch controller)

7. Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

8. MPLS TERMINOLOGY • Label – short identifier with fixed length and local significance • Label Switching Router (LSR) - router supporting MPLS • Label Edge Router (LER) - an LSR at the edge of an MPLS network • Label Information Base – database holding the label mappings, “forwarding table” • Label Switched Path (LSP) – the path is made up of one or more hops with label switching. This is the path traversed by a FEC. • Forwarding Equivalence Class – a set of layer 3 packets which are given the same treatment (same QoS, in other words), and are assigned the same label at an ingress node.

9. Terminology (2) Data traffic Edge LSR Edge LSR Core LSR Core LSR LSR LSR LSR LSR Downstream LSR Egress LSR Ingress LSR Upstream LSR Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers LSR LSR LDP MPLS domain

10. What is MPLS used for?Scalable network layer routing • Labels support aggregation of forwarding information LSR LSR LSR LSR LSR LSR LSR LSR Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

11. What is MPLS used for?Traffic control/engineering • Traffic engineerng is ”Killer-app”for MPLS • explicit routing may be used for traffic engineering, e.g. QoS/policy and load balancing Route selected by theIP routing protocol LSR LSR LSR Route specified by explisit routing in MPLS LSR LSR LSR

12. Predefined paths for each VPN Ingress LSR attaches the labels to the packets Packets are not routed based on IP May use private IP addresses internally in a VPN WHAT IS MPLS USED FOR? VPN

13. LABELS – USAGE • Simple usage: destination based unicast-traffic • Label-granularity: • Source – destination IP addresses and TCP/UDP ports • Source – destination with the same ToS • Same destination network • Same egress-LSR

14. Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

18. Request: 47.1 Request: 47.1 Mapping: 6 Mapping: 5 MPLS - label distribution 1 47.1 3 3 2 1 1 2 47.3 3 47.2 2 Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

19. IP 47.1.1.1 IP 47.1.1.1 Label Switched Path (LSP) 1 47.1 3 3 2 1 1 2 47.3 3 47.2 2 Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

20. LABEL-STACK swap • Every packet may include a stack (LIFO) of labels • Operations: push, pop, swap, noop • Forwarding based on the top label in stack • Allows multiple traffic patterns • May be used to combine and split MPLS flows • Increases scalability and efficiency, but increases complexity • It is possible to map multiple incoming labels to one outgoing label – label merging push pop L4 L2 L1 1) (ATM) 2) (ATM) 3) 4)

21. LABEL DISTRIBUTION • Piggyback on other protocols (OSPF, BGP, RSVP) • explicit transmission of label information between LSRs using the Label Distribution Protocol • Other relevant attributes to exchange? • Criteriasfor triggering the establishment? • Which protocols and nodes take initiative to establish an LSP? • explicit or hop-by-hop route selection? • How to distribute information between nodes along the path?

22. MPLS - control and transport planes • MPLS consists of two logically separate planes • Control plane • A collection of protocols implemented as software processes • Establishment of LSPs • Distribute and manage network topology and resource availability • Signaling functions to establish and tear down LSPs • Forwarding plane • Label swapping operations using lookup-tables • Usually implemented in hardware

23. Why Traffic Engineering with MPLS? • Earlier solutions (like traffic engineering over ATM and fame delay) were expensive and harder to manage/operate • Fewer network elements • Lower operating costs • Greater reliability because fewer network elements exist along the routed path • Potentially less latency • Simplified network architectures

24. Traffic engineering process model • Policy formation phase • Formulation of appropriate control policies • Data acquisition phase • Data is collected from the operational network through a measurement system • Analysis and characterization phase • Analysis and characterization of the traffic workload derived from the measurement phase • Performance optimization phase • LSP creation, network expansion, rerouting

25. Traffic engineering process model • Source: Generalized Multiprotocol Label Switching: An Overview of Signaling Enhancements and Recovery Techniques , IEEE Communication Magazine, July 2001., A. Banerjee et. al.

26. MPLS and DiffServ • DiffServ is a mechanism at layer 3 • DiffServ differentiates traffic in queues and offers a possibility to control the forwarding of packets beyond ”best-effort • EF (Expedited Forwarding) • AF (Assured Forwarding) • BE (Best Effort) • MPLS is a protocol at a lower layer – somewhere between layer 2 and 3 • MPLS establishes LSPs and offers better control of the network topology and how packets are forwarded beyond ”shortest path” forwarding. • They have advantages on their own or together

27. MPLSService quality • Labels may identify traffic with special requirements • Diffserv in MPLS: • The DS byte is mapped to the label CoS (3 bit) • Establishment of LSPs associated with QoS

28. LSR E-LSP AF1 EF MPLS QoSE-LSP Example - EXP-inferred-LSPs (E-LSPs): the behavior aggregate of each packet is inferred by the EXP bits in the MPLS label. • The example shows support for both EF and AF1 on the same LSP • Note: EF and AF1 packets uses the same LSP (same label), but are placed in different queues based on the EXP value Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

29. LSR L-LSPs MPLS QoSL-LSP Example - Label-inferred-LSPs: the behavior aggregate for packets is inferred from the label assigned to each packet. • L-LSPs may be established with different label distribution protocols (LDP or RSVP) • The example shows a solution with support for EF and AF1 on different L-LSPs • EF and AF1 packets are transferred on separate LSPs and are put in different queues • The queues are chosen based on the label value • Dropping depends based on the EXP-field Pictures from: RST 1101 - Introduction to MPLS by CISCO Networkers

30. Problems with TE with MPLS • Mapping ingress traffic into FECs. • Mapping FECs onto LSPs • Mapping LSPs onto the physical network topology. - These problems are addressed by the LDP during the following phases: • LDP peer discovery • LDP session establishment • Management label binding and label distribution

31. Generalized Multiprotocol Label Switching (GMPLS) • Extends the MPLS control plane to support more types of interfaces and switching technologies: • Time Division Multiplexing (TDM), wavelength switching, fiber switching as well as packet switching… • Generalized labels; can represent a single fiber in a bundle, a single waveband within a fiber, a single wavelength within a waveband (or fiber), or a set of time-slots within a wavelength (or fiber) • GMPLS allows for a greatly increased number of parallel links between nodes in a network. This is important in photonic networking, where hundreds of parallel links (individual fibers in a bundled fiber optic cable, for example) may exist between a pair of nodes. • GMPLS also facilitates rapid fault detection, fault isolation, and switchover to alternate channels, minimizing network downtime.

32. An example of a GMPLS LSP Source: Generalized Multiprotocol Label Switching: An Overview of Signaling Enhancements and Recovery Techniques , IEEE Communication Magazine, July 2001., A. Banerjee et. al.

33. Bidirectional LSPs • A requirement for many optical networking service providers • Two unidirectional LSPs in opposite directions are established independently • Establishment latency • Control overhead is twice that of a unidirectional LSP • Route selection can be complicated since resources are established in separate segments

34. Notify messages The node passing transient traffic is responsible for notifying the nodes that can restore the connection in case of errors, with out the intermediate nodes processing the message. • ‘ Notify message’ feature is added to RSVP-TE for GMPLS to provide a mechanism for informing nonadjacent nodes of LSP-related failures. This feature is not added in CR-LDP.

35. GMPLS Protection and restoration techniques • Fault management consists of four primary steps; 1) Detection, 2) Localization, 3) Notification, 4) Mitigation • Protection and restoration is used to mitigate the failure • Protection • requires pre-allocated resources • is designed to react to failures rapidly (< 200 ms) • requires simultaneous transmission along a primary and a secondary path (1+1 protection) • requires twice as many network resources • Restoration • relies on dynamic resource establishment • may take a longer time to restore the connection than protection switching • may involve dynamic route calculation

36. Protection mechanisms • 1+1 protection - data is distributed simultaneously over two paths • M:N protection - M pre-allocated backup paths shared among N primary paths • 1:N protection - 1 pre-allocated paths pr. N primary paths • 1:1 protection - 1 pre-allocated path for 1 primary path • Span protection - Carried out between two adjacent nodes • Path protection - Carried out at the end nodes

37. 1+1 path protectiondata is distributed simultaneously over two paths Working B A Protection

38. 1:1 Span Protection1 pre-allocated path for 1 primary path Primary A B Backup

39. Restoration mechanisms • Similar to protection it can be implemented at the source or an intermediate node once the responsible node has been notified • Failure notification • Line Restoration - traffic is routed around a failure, a new path is selected at an intermediate node • Path Restoration - routes traffic to an alternate route around a failure, a new path is selected the source node

40. Path restoration Source Destination Notify Notify

41. MPLS & GMPLSSummary • MPLS • Scalable network layer routing • Labels offer the possibility to aggregate forwarding information • More flexible traffic control • Labels identifies traffic with special requirements (e.g. QoS) • Labels allow the possibility to support explicit routing (traffic engineering, load balancing) • Increase performance (?) • label-swapping to optimize network performance • GMPLS extends MPLS to manage more classes of interfaces • Enhances the Multiprotocol Label Switching (MPLS) to support network switching for time, wavelength, and space switching as well as for packet switching. In particular, GMPLS will provide support for photonic networking, also known as optical communications.

42. References • Generalized Multiprotocol Label Switching: An Overview of Signaling Enhancements and Recovery Techniques., IEEE Communication Magazine, July 2001. A. Banerjee et. al. • Internet traffic engineering using multi-protocol label switching (MPLS)., Computer Networks 40, Elsevier, 2002, D.O. Awduche and B. Jabbari.