1 Presentation_ID © 1999, Cisco Systems, Inc. MPLS Basics and Applications Peter Tomsu Senior Consultant Cisco Systems EMEA Peter Tomsu Senior Consultant Cisco Systems EMEA

2 Presentation_ID © 1999, Cisco Systems, Inc. 2 Presentation_ID © 1999, Cisco Systems, Inc. MPLS Basics

3oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Peer Model OSPF, BGP PNNI OSPF, BGP Overlay Model eg Classical IP, MPOA, NHRP Routers and Switches totally isolated Routers have no idea of ATM Topo IP features must be approximately mapped into ATM Peer Model eg MPLS Routers and Switches totally integrated Routers & Switches share topology IP features directly supported by ATM

4oebb_update_062k © 1999, Cisco Systems, Inc. Peer vs Overlay Overlay Model: IP Intelligence Around Peer Model: IP Intelligence at every hop

5oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Switching - Overview I/f 0 I/f 4 I/f 1 Unlabeled Data Label Switch Router LSR Label Switch Router LSR Label Edge Router ingress LER Label Edge Router ingress LER Label Edge Router egress LER Label Edge Router egress LER Label Edge Router egress LER Label Edge Router egress LER MPLS Domain Labeled Data Unlabeled Data

6oebb_update_062k © 1999, Cisco Systems, Inc. CEF Forwarding Table Populated with Routing Topology Information Each Route/Prefix Mapped to a Label Value Switching Decision Then Only ‘Label-Swaps’ via the Label Information Base (LIB) … … … … Local Lbl Local Lbl Remote Lbl Remote Lbl Address Prefix Address Prefix Interface 0 I/f 4 I/f Data … … X X X X … … Local Lbl Local Lbl Remote Lbl Remote Lbl Address Prefix Address Prefix Interface.. Unlabeled Data MPLS Switching—Example Data Data Data Unlabeled Data Label Information Base Label Information Base

7oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Switching— FECs B C D E A Dest: B Dest: C Dest: D Dest: E FEC1 FEC2 LSR VLSR X LSR Y LSR Z Dest: B Dest: C FEC1 3 3 Dest: D Dest: E FEC2 4 4 LIB LSR X INOUTINTF intf 0 intf 1 FEC … Forwarding Equivalent Class The ingress router can use additional information when it is assigning packets to a FEC, like incoming port ToS bits source address any arbitrary information

8oebb_update_062k © 1999, Cisco Systems, Inc. Generic Label Encapsulation Lbl Stack L2 Header Layer 3 Header L2 Header (PPP/Ethernet/...) Generic Encapsulation/ Shim Header Label (0) ExpSTTL 20 Bits 3 Bits 1 Bits 8 Bits EXP … Experimental Use (used as QoS bits) S ……. Bottom of Stack (set to 1 for last entry, o for all other label stack entries) TTL … Time to Live

9oebb_update_062k © 1999, Cisco Systems, Inc. Label Stack Lbl Stack L2 Header Layer 3 Header Label (0) ExpSTTL Label (1) ExpSTTL The Label Stack consists of a sequence of Label Stack Entries equal or greater 1...

10oebb_update_062k © 1999, Cisco Systems, Inc. ATM Label Encapsulation ATM Cell Header HEC Lbl DATA CLP PTI VCI GFC VPI Lbl Top Label encoded in VPI/VCI fields Top Label and subsequent Labels (if present) are also encoded with generic encapsulation (+CoS, +TTL fields)

11oebb_update_062k © 1999, Cisco Systems, Inc. Label Allocation “Downstream on Demand” Upstream LSR Downstream LSR 1. Label Request Message for Label n 2. Label Mapping Message for Label n Packets with Label n

12oebb_update_062k © 1999, Cisco Systems, Inc. Label Distribution LSR XLSR Y OSPF, IS-IS, etc... Layer 3 Routing Protocol LDP, RSVP, mp-BGP-4, etc... Label Distribution Protocol ATM, PPP, Ethernet, PoSIP, etc Data Link Technology

13oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Example: Routing Information You can reach through me You can reach and through me Routing Updates (OSPF, IS-IS, …) You can reach through me 2 1 In Lbl In Lbl Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In Lbl In Lbl In Lbl In Lbl

14oebb_update_062k © 1999, Cisco Systems, Inc MPLS Example: Requesting Labels I need a Lbl for Label Distribution Protocol (LDP) (Downstream on Demand Allocation) I need a Lbl for I need a Lbl for I need another Lbl for I need a Lbl for I need a Lbl for In Lbl In Lbl Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In Lbl In Lbl In Lbl In Lbl

15oebb_update_062k © 1999, Cisco Systems, Inc MPLS Example: Assigning Labels Use Lbl 9 for Use Lbl 10 for Use Lbl 7 for Use Lbl 4 for Use Lbl 5 for Use Lbl 8 for In Lbl In Lbl Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In Lbl In Lbl In Lbl In Lbl

16oebb_update_062k © 1999, Cisco Systems, Inc MPLS Example: Packet Forwarding Data Data Data Data In Lbl In Lbl Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In I/F In I/F Address Prefix Address Prefix Out I’face Out I’face Out Lbl Out Lbl In Lbl In Lbl In Lbl In Lbl LSR forwards based on label Each label defines a different LVC

17oebb_update_062k © 1999, Cisco Systems, Inc. MPLS on ATM Packet Cells ATM Cell Header HEC Label DATA CLP PTI VCI GFC VPI Labels act as the VC identifier for ATM switches (Label VC or LVC) Labels change between switches - LVCs are not end-to-end. MPLS “partition” allocated for each link (no per-VC bandwidth reservation). In Lbl In Lbl Address Prefix Address Prefix Out I/F Out I/F Out Lbl Out Lbl In I/F In I/F

18oebb_update_062k © 1999, Cisco Systems, Inc. With a ATM switch supporting VC-Merge: Can reuse outgoing Label Hardware prevents cell interleave Fewer Labels required, For very large networks In Lbl In Lbl Address Prefix Address Prefix Out I/F Out I/F Out Lbl Out Lbl VC Merge Packet Cells In I/F In I/F

19oebb_update_062k © 1999, Cisco Systems, Inc. MPLS-VPN What is a VPN ? An IP network infrastructure delivering private network services over a public infrastructure Use a layer 3 backbone Scalability, easy provisioning Global as well as non-unique private address space QoS Controlled access Easy configuration for customers

20 Presentation_ID © 1999, Cisco Systems, Inc. 20 Presentation_ID © 1999, Cisco Systems, Inc. MPLS Applications

21oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Traffic Engineering

22oebb_update_062k © 1999, Cisco Systems, Inc. Traffic Engineering: Motivations Reduce the overall cost of operations by more efficient use of bandwidth resources by preventing a situation where some parts of a service provider network are over-utilized (congested) while other parts under-utilized cost saving The ultimate goal is cost saving and maximized performance!

23oebb_update_062k © 1999, Cisco Systems, Inc. Traffic Engineering’s Job Construct routes for traffic streams within a service provider network to avoid causing some parts of the provider’s network to be over-utilized while others parts remain under-utilized

24oebb_update_062k © 1999, Cisco Systems, Inc. Traffic Engineering With Overlay R2 R3 R1 PVC for R2 to R3 traffic PVC for R1 to R3 traffic

25oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Traffic Engineering R8 R2 R6 R3 R4 R7 R5 R1 MPLS LSP for R8 to R5 traffic MPLS LSP for R1 to R5 traffic

26oebb_update_062k © 1999, Cisco Systems, Inc. TE Example Deployment Find route & set-up tunnel for 20 Mb/s from POP1 to POP4 Find route & set-up tunnel for 10 Mb/s from POP2 to POP4 POP4 POP POP2 POP1 WAN area

27oebb_update_062k © 1999, Cisco Systems, Inc. MPLS TE Components (1) Link Attribute Flooding Link state IGP protocols enhanced to advertise Link Resource Attributes Constraint based Routing SPF computation enhanced to compute path which satisfies the resource Constraints (bandwidth, policy) for a TE tunnel TE Tunnel establishment RSVP signaling extended (eg label binding) to set-up the LSP along the route computed by Constraint Base Routing

28oebb_update_062k © 1999, Cisco Systems, Inc. MPLS TE Components (2) MPLS Forwarding LFIB handles the forwarding “as usual” only - LFIB has been populated by another Control module than Destination Based LDP Routing Traffic over TE Tunnels IGP enhanced on tunnel Head-ends to “route” IP packets “into” TE tunnels

29oebb_update_062k © 1999, Cisco Systems, Inc. Constrained Based Routing

30oebb_update_062k © 1999, Cisco Systems, Inc. Path Computation Input: – constraints imposed by TE tunnel to be routed – resource attributes of every link (bandwidth, Resource Class affinity, metric) available from IS-IS or OSPF

31oebb_update_062k © 1999, Cisco Systems, Inc. Path Computation Prune links if: insufficient resources (e.g., bandwidth) violates policy constraints Compute shortest distance path R 3 uses its own metric

32oebb_update_062k © 1999, Cisco Systems, Inc. LSP Tunnel Setup

33oebb_update_062k © 1999, Cisco Systems, Inc. TE Tunnel Setup Initiated at the head-end of a trunk Uses Explicit Route calculated by Constraint Based Routing or configured manually by operator Uses RSVP (with few extensions) to establish Label Switched Paths (LSPs) for TE tunnel

34oebb_update_062k © 1999, Cisco Systems, Inc. Fast Restoration Handling link failures - two complementary mechanisms: Path protection Link protection

35oebb_update_062k © 1999, Cisco Systems, Inc. Link Protection for R2-R4 Link Setup: Path (R2->R6->R7->R4) Labels Established on Resv message R8 R2 R6 R4 R7 R1 R5 R9

36oebb_update_062k © 1999, Cisco Systems, Inc. TE Tunnel Prior to Link Failure R8 R2 R6 R4 R7 R1 R5 R9 Setup: Path (R1->R2->R4->R9) Labels Established on Resv message

37oebb_update_062k © 1999, Cisco Systems, Inc. Link Protection Active R8 R2 R6 R4 R7 R1 R5 R9 On failure of link from R2 -> R4, R2 simply changes outgoing Label Stack from to

38oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPN QoS And Traffic Engineering

39oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPN QoS and Traffic Engineering POP4 POP POP2 POP1 WAN area MPLS VPN service unchanged: MPLS VPN QoS SLA exactly as defined earlier Traffic Engineering in core to reduce cost MPLS TE Question: How many MPLS labels ???

40oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPN QoS and Traffic Engineering POP4 POP POP2 POP1 WAN area LDP iBGP RSVP User IP Packet Answer: 3 labels

41oebb_update_062k © 1999, Cisco Systems, Inc. Carrying Service Class Information: Packet Media IPv4 Header Layer 2 Header Payload IPv4 Header IPv6 Header Layer 2 Header Payload IPv6 Header Type of Service field (old definition) Diffserv field (expanded definition) Diffserv field (supercedes the Traffic Class octet) MPLS Header Layer 2 Header L3 Header & Payload Packet-based MPLS Different labels to each destination for different Classes

42oebb_update_062k © 1999, Cisco Systems, Inc. Carrying Service Class Information: ATM Different LVCs to each destination for different Classes. LVCs have DiffServ service types, not ATM Forum CBR, UBR, VBR or ABR ATM Cell HeaderHEC Label DATACLPPTIVCIGFCVPI

43oebb_update_062k © 1999, Cisco Systems, Inc. ATMF Queues PVC/SVC Traffic IP Traffic ? Traditional ATM Switch: No IP Awareness MPLS+DiffServ model: Separate DiffServ Queues & Policies on the ATM switch ATMF Queues PVC/SVC Traffic IP Traffic IP Queues PVC/SVC Traffic IP Traffic Carrying Service Class Information: ATM

44oebb_update_062k © 1999, Cisco Systems, Inc. Spare Time Premium Traffic Bandwidth Best effort: little guaranteed Best Effort Traffic But premium traffic is guaranteed access to most of the bandwidth, if it needs it. Differentiated Service on a Link: Two Classes Premium traffic can have extra bandwidth allocated to it, which it will use only if needed. Premium traffic gets excellent QoS, as if it has bandwidth over-engineered for it ‘Best Effort’ traffic gets access to bandwidth unused by premium traffic: little or no wasted bandwidth. Estimated premium traffic

45oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPN QoS Model

46oebb_update_062k © 1999, Cisco Systems, Inc. How It Feels for a CPE: Routing Viewpoint MPLS VPN Layer 2 VPN Layer 2 VPN : Physical View Layer 2 VPN : Logical View MPLS VPN : Physical View MPLS VPN : Logical View

47oebb_update_062k © 1999, Cisco Systems, Inc. How It Feels for a CPE: Routing Viewpoint Routing Adjacencies: Before MPLS VPN: point-to-point to all remote sites With MPLS VPN: point-to-cloud “Point-to-Cloud” is key to MPLS VPN benefits from Routing Viewpoint

48oebb_update_062k © 1999, Cisco Systems, Inc. How It Feels for a CPE: QoS Viewpoint MPLS VPN Layer 2 VPN Layer 2 VPN : Physical View Layer 2 VPN : Logical View MPLS VPN : Physical View MPLS VPN : Logical View

49oebb_update_062k © 1999, Cisco Systems, Inc. How It Feels for a CPE: QoS Viewpoint QoS Commitment: Before MPLS VPN point-to-point to all remote sites With MPLS VPN: point-to-cloud this is exactly the Diff-Serv model “Point-to-Cloud” is key to MPLS VPN benefits from QoS Viewpoint scalability in SP Backbone simplicity for Customer

50oebb_update_062k © 1999, Cisco Systems, Inc. Any to any connectivity... … without requiring the customer to know or specify its traffic matrix Changes in traffic matrix accommodated by SP without changes in the QoS contract Preserves MPLS VPN scalability no “per- VPN-Site” awareness in SP backbone Resource Allocation by SP is at very aggregate level per COS easier, higher statistical gain Benefits of the “Point-to-Cloud” Model

51oebb_update_062k © 1999, Cisco Systems, Inc. How to Build “Point-to-Cloud” Service? Scenario 1 : – Constrained access – Unconstrained Backbone MPLS VPN Diff-Serv o IP Best-Effort o IP

52oebb_update_062k © 1999, Cisco Systems, Inc. How to Build “Point-to-Cloud” Service? Scenario 2 : – Constrained access – Constrained Backbone (or requirement for tightest possible delay) MPLS VPN Diff-Serv o IP Diff-Serv o MPLS

53oebb_update_062k © 1999, Cisco Systems, Inc. How to Build “Point-to-Cloud” Service? Scenario 3 : – Constrained access – Constrained Backbone (or requirement for tightest possible delay) – Requirement to maximise use of backbone resources Diff-Serv o IP MPLS VPN Diff-Serv o MPLS Traffic Engineering o MPLS MPLS VPN QoS does not “require”, but can benefit from, MPLS Traffic Engineering Does not change the “Point-to-Cloud” model Opportunity to reduce cost Opportunity to improve QoS target (eg. delay)

54oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPN QoS - Conclusions Key MPLS VPN QoS Service is “point-to-cloud” MPLS QoS number one goal is to support Diff-Serv, the whole of Diff-Serv and nothing but Diff-Serv For Service Provider, MPLS Diff-Serv deployment is virtually the same as IP Diff-Serv deployment activate Diff-Serv queuing/dropping perform Diff-Serv capacity planning on ATM PVCs Model is IP QoS and not Layer 2 QoS no per-VPN QoS rather, per Class QoS each VPN can use multiple Classes

55oebb_update_062k © 1999, Cisco Systems, Inc. DiffServ over MPLS Standardization Update

56oebb_update_062k © 1999, Cisco Systems, Inc. IETF Progress draft-ietf-mpls-diff-ext-03.txt Working Group document (optimistic) goal: Last Call at April Adelaide meeting

57oebb_update_062k © 1999, Cisco Systems, Inc. Diff-Serv over MPLS: “Colouring” MPLS Frames Two methods are possible – Single LSP per FEC use EXP field in MPLS header to select Diff-Serv queue –E-LSP – Multiple LSPs per FEC use label to select Diff-Serv queue –L-LSP

58oebb_update_062k © 1999, Cisco Systems, Inc. Yet More Terminology E-LSP behavior (queue & drop) inferred from E XP bits only Allows up to 8 BAs on an LSP L-LSP behavior inferred from L abel (and perhaps EXP bits too) for AFxy, label determines the queue, EXP bits determine drop preference

59oebb_update_062k © 1999, Cisco Systems, Inc. E-LSPs and L-LSPs MPLS over PPP and LAN: both E-LSPs and L-LSPs allowed MPLS over ATM/FR: only L-LSPs possible (EXP is not seen)

60oebb_update_062k © 1999, Cisco Systems, Inc. Using the EXP Bits: E-LSP Mapping of IP DSCP into MPLS EXP DSCP= xxxxxx IPv4 Packet MPLS Hdr MPLS EXP= yyy Non-MPLS Diff-Serv Domain MPLS Diff-Serv Domain | Label | EXP |S| TTL | DSCP= xxxxxx

61oebb_update_062k © 1999, Cisco Systems, Inc. Using the EXP bits: E-LSP LDP or RSVP establishes one E-LSP per FEC Queue is selected based on EXP E-LSP LSR LDP

62oebb_update_062k © 1999, Cisco Systems, Inc. Using Multiple LSPs: L-LSPs LDP or RSVP establishes multiple L-LSPs per FEC Queue is selected based on label L-LSPs LSR LDP

63oebb_update_062k © 1999, Cisco Systems, Inc. MPLS COS Phase 2 COS Translation

64oebb_update_062k © 1999, Cisco Systems, Inc. COS Translation for DiffServ IP Transport MPLS VPN IP with Full Diff-Serv 6-bit DS IP with Full Diff-Serv 6-bit DS Allows operations of Diff-Serv IP over MPLS backbone (VPN or non-VPN) only max 8 COS supported by the MPLS cloud --> if more than 8 COS (BAs) supported in IP clouds they have to be mapped onto the MPLS backbone 8 COS

65oebb_update_062k © 1999, Cisco Systems, Inc. COS Translation Developed as flexible translation: – COS={Prec, DS, EXP, CLP} – COS translation = Translation from any* to any * except from CLP

66oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth

67oebb_update_062k © 1999, Cisco Systems, Inc. MPLS as the MultiService Infrastructure: Layer Collapsing IP WDM ATM SDH Applications Fast Restoration Traffic Engineering Transport IP WDM MPLS Admission Control Hard Pt-2-Pt QoS Soft Pt-2-Cloud QoS MPLS

68oebb_update_062k © 1999, Cisco Systems, Inc. MPLS as the MultiService Infrastructure: Layer Collapsing IP WDM ATM SDH Applications Fast Restoration Traffic Engineering Transport IP WDM MPLS Admission Control Hard Pt-2-Pt QoS Soft Pt-2-Cloud QoS + MPLS Guaranteed Bandwidth

69oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Service Provisioned Diff-Serv COS is fine for many end- customer application’s requirements Special services (voice, bandwidth trading, Carrier’s Carrier…) need guarantees and tighter QoS Massive over-provisioning cannot always be assumed everywhere in network MPLS Guaranteed Bandwidth: offers Layer-2-like point-to-point QoS commitments while preserving MPLS/IP scalability

70oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Service MPLS Guaranteed Bandwidth Service unidirectional Point-to-point Bandwidth with commitment on QoS parameters CE N1 Mb/s Guarantee N2 Mb/s Guarantee

71oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Mechanisms MPLS Guaranteed Bandwidth = Traffic Conditioning on Edge + Queues/PHBs in Core + COS-aware Routing + COS-aware Admission Control Diff-Serv MPLS TE with COS awareness

72oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Mechanisms 50 Mb/s P_inP_out 100 Mb/s MPLS Traffic Engineering for GB: (aggregated: one GB Tunnel for multiple services) Mb/s from P_in to P_out - COS aware Routing - COS aware Admission Control Diff-Serv Traffic Conditioning: (on a per e2e service basis) - Classification - Metering - Marking - Policing Diff-Serv PHB: (even more aggregated: one Diff-Serv queue) Diff-Serv MPLS

73oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Mechanisms 50 Mb/s P_inP_out 100 Mb/s IGP advertises non-reserved bandwidth on every link More on MPLS Traffic Engineering for GB:

74oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Mechanisms 50 Mb/s P_inP_out 100 Mb/s More on MPLS Traffic Engineering for GB: P_in performs Constraint Based Routing: finds a Path with sufficient non-reserved bandwidth for GB

75oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth: The Mechanisms 50 Mb/s P_inP_out 100 Mb/s More on MPLS Traffic Engineering for GB: P_in sends MPLS signalling for establishment of GB Tunnel along computed path admission control performed on every link

76oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth for Voice GW PSTN Call Agent GW ensures that Voice Load is below configured X% on EVERY link (--> Guaranteed QoS) GB Tunnel

77oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth for Voice GW PSTN Call Agent GW explicit rejection of new Tunnels if there is no path that can meet QoS (--> explicit knowledge that extra resources required) GB Tunnel

78oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth for Voice GW PSTN Call Agent GW Voice Traffic distributed over alternate path if required: “Traffic Engineering” of Voice GB Tunnel

79oebb_update_062k © 1999, Cisco Systems, Inc. MPLS Guaranteed Bandwidth for Voice GW PSTN Call Agent GW MPLS Fast Reroute: Voice calls not affected by failure GB Tunnel

80oebb_update_062k © 1999, Cisco Systems, Inc. MPLS VPNs

81oebb_update_062k © 1999, Cisco Systems, Inc. Managed IP Services Scale to Large and Small Customers Single carrier network supporting multiple customer IP VPNs Separately engineered customer private IP networks BGP/MPLS VPN Network Vs.

82oebb_update_062k © 1999, Cisco Systems, Inc. Enterprise C Enterprise A Enterprise B Intranet VPN 10 Extranet VPN 20 Internet Backbone— “VPN 0” MPLS—Foundation for L3 VPNs VPNs uniquely defined via Label + VPN ID decoupling forwarding from IP addressing Data privacy via logically separated label switched paths Quaility-of-Service (Label CoS) Provides IP address uniqueness Eliminates tunnel mesh Enterprise B Enterprise A

83oebb_update_062k © 1999, Cisco Systems, Inc. CE PE IGP (e.g. OSPF)/TDP eBGP/ Static/RIP iBGP VPN-Aware Network Routing Architecture 1. SP network uses an IGP to exchange local reachability 2. CEs (customer edge) and PEs (provider edge) exchange routing info (IP) 3. PEs exchange VPN routing info and tag bindings (VPN-IP) via mBGP (RFC2283) 4. LDP is used to bind tags to routes in the core

84oebb_update_062k © 1999, Cisco Systems, Inc. Cust A VPN 15 Cust A VPN 15 Cust B VPN 354 (15) (354) (354) (15) (15) Private View Internet Scale VPN Controlled Route Distribution via Selective Advertisement MPLS VPN—Network Formation Cust A VPN 15 Cust B VPN 354 Public View Forwarding Examples IN OUT (15) (15) (15) (15) (15) (354) (354)

85 Presentation_ID © 1999, Cisco Systems, Inc.