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MPLS Introduction

MPLS Introduction

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Almog Ohayon

May 19, 2013
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  1. Label Format LABEL EXP S TTL 0 19 22 23

    31 20 24 Label Header MAC Header Layer 3 Header ©2013, Cisco Systems. Inc. All rights reserved.
  2. MPLS Label Stack Frame header Label 1 IP header Payload

    Label 2 Label 3 PID=MPLS-IP ©2013, Cisco Systems. Inc. All rights reserved.
  3. MPLS Label Stack • MPLS/VPNs • Traffic Engineering • MPLS/VPNs

    combined with Traffic Engineering ©2013, Cisco Systems. Inc. All rights reserved.
  4. MPLS Architecture Data plane Control plane OSPF: 10.0.0.0/8 LDP: 10.0.0.0/8

    Label 17 OSPF LDP LFIB LDP: 10.0.0.0/8 Label 4 OSPF: 10.0.0.0/8 417 Labeled packet Label 4 Labeled packet Label 17 ©2013, Cisco Systems. Inc. All rights reserved.
  5. Frame Mode MPLS Frame header IP header Payload Layer 2

    Layer 3 Frame header Label IP header Payload Layer 2 Layer 2½ Layer 3 Routing lookup and label assignment ©2013, Cisco Systems. Inc. All rights reserved.
  6. LSR and eLSR • Label Switch Router (LSR) • Edge

    LSR ©2013, Cisco Systems. Inc. All rights reserved.
  7. Architecture of LSRs LSR Control plane Data plane Routing protocol

    Label distribution protocol Label forwarding table IP routing table Exchange of routing information Exchange of labels Incoming labeled packets Outgoing labeled packets ©2013, Cisco Systems. Inc. All rights reserved.
  8. Architecture of Edge LSRs Edge LSR Control plane Data plane

    Routing protocol Label distribution protocol Label forwarding table IP routing table Exchange of routing information Exchange of labels Incoming labeled packets Outgoing labeled packets IP forwarding table Incoming IP packets Outgoing IP packets ©2013, Cisco Systems. Inc. All rights reserved.
  9. MPLS Forwarding • Push • Swap • Pop ©2013, Cisco

    Systems. Inc. All rights reserved.
  10. MPLS Example 10.1.1.1 10.1.1.1 Routing lookup and label assignment 10.0.0.0/8

     L=5 Label swapping L=5  L=3 Label removal and routing lookup L=3 ©2013, Cisco Systems. Inc. All rights reserved.
  11. TDP vs. LDP • MPLS Tag Switching 711. 646. ©2013,

    Cisco Systems. Inc. All rights reserved.
  12. LDP Session Negotiation 1.0.0.1 MPLS_A 1.0.0.2 MPLS_B Initialization message Establish

    TCP session Initialization message Keepalive Keepalive ©2013, Cisco Systems. Inc. All rights reserved.
  13. Before MPLS VPN PE CE VPN-A VPN-B CE VPN-C CE

    Paris London Munich interface Serial0/1 description ** interface to VPN-A customer ip address 192.168.61.6 255.255.255.252 ip access-group VPN-A in ip access-group VPN-A out ! interface Serial0/2 description ** interface to VPN-B customer ip address 192.168.61.9 255.255.255.252 ip access-group VPN-B in ip access-group VPN-B out ! interface Serial0/3 description ** interface to VPN-C customer ip address 192.168.62.6 255.255.255.252 ip access-group VPN-C in ip access-group VPN-C out PE Routing Table VPN-A routes VPN-B routes VPN-C routes ©2013, Cisco Systems. Inc. All rights reserved.
  14. Benefits of MPLS VPNs PE CE VPN-A VPN-A CE VPN-B

    Global Routing Table VRF for VPN-A VRF for VPN-B VPN Routing Table CE Multiple routing & forwarding instances (VRFs) provide the separation Paris London Munich IGP &/or BGP ©2013, Cisco Systems. Inc. All rights reserved.
  15. • PE routers maintain separate routing tables Global routing table

    contains all PE and P routes (perhaps BGP) populated by the VPN backbone IGP VRF (VPN routing & forwarding) routing & forwarding table associated with one or more directly connected sites (CE routers) VRF is associated with any type of interface, whether logical or physical (e.g. sub/virtual/tunnel) interfaces may share the same VRF if the connected sites share the same routing information VPN Routing & Forwarding Instance (VRF) ©2013, Cisco Systems. Inc. All rights reserved.
  16. VRF Route Population locally PE CE C E Site-2 Site-1

    EBGP,OSPF, RIPv2,Static ©2013, Cisco Systems. Inc. All rights reserved.
  17. VRF Route Distribution local imports PE PE CE Router CE

    Router P Router VPN Site VPN Site MP-BGP MPLS/VPN Backbone ©2013, Cisco Systems. Inc. All rights reserved.
  18. Concept of RD PE1 CE VPN-A VPN-B VPN-B CE MP-BGP

    PE2 BGP Table Routes from VPN-A Routes from VPN-B Munich MPLS/VPN Backbone CE router sends 32 bit IPv4 prefix PE router converts it into a 96 bit VPNv4 prefix ©2013, Cisco Systems. Inc. All rights reserved.
  19. MPLS/VPN Packet Forwarding • Label Stack is used for packet

    forwarding Top label indicates BGP Next-Hop (interior label) Second level label indicates outgoing interface or VRF (exterior VPN label) • MPLS nodes forward packets based on top label any subsequent labels are ignored • Penultimate Hop Popping procedures used one hop prior to egress PE router ©2013, Cisco Systems. Inc. All rights reserved.
  20. Transit Autonomous System Traditional BGP Transit Autonomous System Design Requirements

    • All core routers Core1 Border1 Border2 Core2 ISP1 ISP2 EBGP EBGP IBGP IBGP IBGP RR RR ©2013, Cisco Systems. Inc. All rights reserved.
  21. Transit Autonomous System Simplified BGP network design in MPLS-based networks

    • Only border routers Core1 Border1 Border2 Core2 ISP1 ISP2 EBGP EBGP IBGP ©2013, Cisco Systems. Inc. All rights reserved.
  22. MPLS Configuration VRF configuration Ip vrf GREEN rd 109:145 route-target

    export 109:145 route-target import 109:145 interface serial 1/0/1 ip forwarding vrf GREEN ip address 10.1.1.5 255.255.255.252 ©2013, Cisco Systems. Inc. All rights reserved.
  23. MPLS Configuration router bgp 110 neighbor 131.108.1.1 remote-as 110 neighbor

    131.108.1.1 update-source loopback 0 ©2013, Cisco Systems. Inc. All rights reserved.
  24. MPLS Configuration router bgp 110 ! address-family ipv4 vrf Green

    neighbor 10.1.1.1 remote-as 115 neighbor 10.1.1.1 activate ©2013, Cisco Systems. Inc. All rights reserved.
  25. Layer 2 Services Layer 2 MPLS VPN • Virtual Private

    Wire Service (VPWS) – Point-To-Point – Martini – Kompella • Virtual Private LAN Service (VPLS) - Multipoint – Kompella – Lasserre & Vkompella ©2013, Cisco Systems. Inc. All rights reserved.
  26. Martini draft was named after a former Cisco employee Luca

    Martini. Martini draft uses LDP as signaling to setup L2VPN over MPLS backbone. Kompella draft on the other hand uses BGP for both signaling and auto-discovery to establish fully-meshed pseudo wires (multipoint). Kompella-draft is named after author Keerti Kompella (Juniper Employee). Martini Vs. Kompella ©2013, Cisco Systems. Inc. All rights reserved.
  27. Martini draft was named after a former Cisco employee Luca

    Martini. Martini draft uses LDP as signaling to setup L2VPN over MPLS backbone. Martini Vs. Kompella ©2013, Cisco Systems. Inc. All rights reserved.
  28. Kompella draft on the other hand uses BGP for both

    signaling and auto-discovery to establish fully-meshed pseudo wires (multipoint). Kompella-draft is named after author Keerti Kompella (Juniper Employee). Martini Vs. Kompella ©2013, Cisco Systems. Inc. All rights reserved.