MPLS Migration & Deployment Jeremy Lawrence (With a few slides by Tom Downey & Rob Redford) Presentation_ID © 1999, Cisco Systems, Inc Topics • Why Migrate to MPLS? • Packet-based MPLS or ATM MPLS? • IP+ATM Networks & Dual-Backbone Networks • Introducing MPLS to Existing ATM Networks • Routing Planning Issues • Specific Issues for BPX 8600/MGX 8850 Networks • Full Meshes & Scalability Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com Why Migrate to MPLS? © 1999, Cisco Systems, Inc Cisco Confidential Different Solutions for LAN and WAN Campus LAN Layer and Layer LAN Switching • Scale Layer 2, to Gigabit speeds • Any-to-any connectivity • Multimedia support Multiprotocol over ATM (MPOA) WAN • Scalability • Optimize for IP and QoS • Bandwidth optimization • IP Virtual Private Networks Presentation_ID © 2000, Cisco Systems, Inc MPL S www.cisco.com MPLS Concepts Customer sites run ordinary IP Customer sites are connected by Frame Relay, ATM, SDH, Cable, xDSL, Dial, etc Presentation_ID © 2000, Cisco Systems, Inc Label Switch Routers (LSRs): ATM Switches or Routers MPLS in the Network Core Edge Label Switch Routers (LSRs) www.cisco.com Key MPLS Capabilities RSVP IP Multicast IP CoS IP/ATM Integration Presentation_ID © 2000, Cisco Systems, Inc Traffic Engineering VPN’s www.cisco.com Traditional IP over ATM • Put routers around the edge of an ATM network • Connect routers using Permanent Virtual Circuits • This does not provide optimal integration of IP and ATM Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com ATM MPLS • MPLS adds IP Routing Control to an ATM Switch • MPLS enables ATM switches to also act like routers Fully support IP, along with Frame Relay and ATM, on shared ATM backbone Provides optimal IP forwarding capability on an ATM network Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com MPLS Brings IP and ATM Together IP Over ATM • Complex translation required • Overhead limits performance and efficiency IP NHRP NHRP Server RFC 1577 ATM ARP Server PNNI Data path ATM Switch Cisco IP+ATM • No complex translation • Full IP and ATM capabilities • Built-in IP routing Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com Cisco IP+ATM IP AT M Ser vi ce s Ser vi ce s IP PNN MPL I S IP+ATM Switch IP over ATM Integration MPLS: IP Fundamentals • MPLS puts IP services directly on ATM switches RSVP ATM switches support IP protocols directly Avoids complex translations which occur with MPOA • Full support for IP CoS, soon RSVP, & IP multicast Presentation_ID © 2000, Cisco Systems, Inc IP Multicast www.cisco.com IP CoS 10 Option 6: Packet-Based MPLS MPLS with MGX 8850 Edge PXM acting as PVC switch GSR 12000 (or 7200/7500) network running MPLS PoS MPLS Links ATM link carrying PVCs MPLS-over-PVCs MGX 8850 Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 60 Full Meshes & Scalability © 1999, Cisco Systems, Inc Cisco Confidential 61 Full Meshes ATM links Non-MPLS ATM Core MPLS-over-PVCs or VP Tunnels • Run packet-based MPLS over PVCs or PVPs (“VP Tunnels”) • Has the same scaling issues as an ordinary IP overlay • Application: support of VPNs over an existing ATM Network Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 62 Full Mesh Problems • ATM switches not run IP routing (OSPF, ISIS): Physical View All edge routers are neighbors All PVCs are IP links ATM link failure = many PVC reestablishments, potentially many IP link failures IP link failures can cause a storm of routing updates Layer View Traffic scales as N3 • Limit without work-arounds: about 50 edge LSRs • Another issue: each PVC on an Edge LSR uses Interface Descriptor Block (IDB) Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 63 Work-Arounds & Scaling Options Separated Meshes: 1(a) VP Tunnel Network Divided by ATM LSRs 1(b) PVC Network Divided by Core Routers Full MPLS: 2(a) ATM MPLS 2(b) Router-based MPLS Partial Mesh Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 64 1(a) VP Tunnel Network With ATM LSRs Add ATM MPLS Functionality to Some Switches `One-armed’ ATM-LSR Non-MPLS ATM Cores Simpler mesh of PVPs • Add ATM MPLS to some existing switches, or add new switches • PVP mesh is broken into smaller meshes, each with up to about 50 nodes Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 65 1(b) PVC Network Divided by Core Routers Add Packet-based Label Switch Routers with ATM interfaces Simpler mesh of PVCs • Add some router-based LSRs (Cisco 7500, 12000) to core • PVC mesh is broken into smaller meshes, each with up to about 50 nodes Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 66 Separated Meshes: Evaluation • Pros: Meets IP routing scalability requirements Reduces complexity of meshes, dimensioning problems, etc Reduces IDB requirements on Edge LSRs somewhat • Cons: Requires additional equipment The performance requirements on the core LSRs may be infeasibly high Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 67 2(a) ATM MPLS Ordinary ATM Connection ATMLSRs Ordinary ATM switch, if required VP tunnels are not required between adjacent ATM-LSRs • Add more ATM-LSRs for optimum scalability & simplicity • Ordinary ATM connections can still be used through ATM Label Switches • Parts of the network can still use ordinary ATM switches, if required Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 68 2(b) Router-based MPLS Router-Based MPLS Network • Add more Router-based LSRs and connect the Edge LSRs to them • Network is now a dual-backbone network Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 69 Full MPLS: Evaluation • Pros: Meets & exceeds IP routing scalability requirements Minimizes MPLS network complexity Reduces IDB requirements on Edge LSRs to minimum Can readily meet performance requirements • Cons Can require much additional equipment Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 70 Partial Mesh Non-MPLS ATM Core Partial mesh of PVCs: some links ‘missing’ Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 71 Partial Mesh: Evaluation Pros • Scope for broadcast storms is reduced by limiting the connectivity of each router, guaranteeing network stability • No additional equipment • Reduces IDB requirements on Edge LSRs somewhat Cons • Traffic takes inefficient, multi-hop paths Edge routers also handle transit traffic • Edge router capacity downgraded by significant amounts of transit traffic • Network inefficiency (i.e the proportion of transit traffic per edge LSR) will tend to increase as the network grows Presentation_ID © 2000, Cisco Systems, Inc www.cisco.com 72 Presentation_ID © 2001, Cisco Systems, Inc 74 ... customer IP VPNs MPLS Network Build once, Sell many Presentation_ID © 2000, Cisco Systems, Inc www .cisco. com 14 VPNs using MPLS & Border Gateway Protocol (BGP) Corp A Site Connectionless IP VPNs Corp... Presentation_ID © 2000, Cisco Systems, Inc www .cisco. com ATM MPLS • MPLS adds IP Routing Control to an ATM Switch • MPLS enables ATM switches to also act like routers Fully support IP, along... for BPX 8600/MGX 8850 Networks • Full Meshes & Scalability Presentation_ID © 2000, Cisco Systems, Inc www .cisco. com Why Migrate to MPLS? © 1999, Cisco Systems, Inc Cisco Confidential Different Solutions