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MPLS Traffic Engineering George Swallow swallow@cisco. com Traffic Engineering © 1999, Cisco Systems, Inc. MPLS Traffic Engineering George Swallow [email protected] com Traffic Engineering © 1999, Cisco Systems, Inc. 1

What is Traffic Engineering Taking control of how traffic flows in your network in What is Traffic Engineering Taking control of how traffic flows in your network in order to - ØImprove overall network performance ØOffer premium services ØAs a tactical tool to deal with network design issues when the longer range solution are not deployed Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 2

Voice Traffic Engineering • Telco’s noticed that demands vary widely by time of day Voice Traffic Engineering • Telco’s noticed that demands vary widely by time of day • Began “engineering the traffic” long ago • Evolved over time • Now fully automated Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 3

Reasons for Traffic Engineering • • Traffic Eng. Economics – more packets, fewer $$$ Reasons for Traffic Engineering • • Traffic Eng. Economics – more packets, fewer $$$ Address deficiencies of IP routing Tactical tool for network operations Class-of-service routing © 1999, Cisco Systems, Inc. Cisco Systems 4

Economics of Traffic Engineering “The efficacy with which one uses the available bandwidth in Economics of Traffic Engineering “The efficacy with which one uses the available bandwidth in the transmission fabric directly drives the fundamental ‘manufacturing efficiency’ of the business and its cost structure. ” Mike O’Dell, UUnet Savings can be dramatic. Studies have shown that transmission costs can be reduced by 40%. Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 5

The “Fish” Problem a deficiency in IP routing R 8 R 3 R 4 The “Fish” Problem a deficiency in IP routing R 8 R 3 R 4 R 2 R 5 R 1 R 6 R 7 IP uses shortest path destination based routing Shortest path may not be the only path Alternate paths may be under-utilized while the shortest path is over-utilized Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 6

Deficiencies in IP Routing • Chronic local congestion • Load balancing Across long haul Deficiencies in IP Routing • Chronic local congestion • Load balancing Across long haul links • Size of links Difficult to get IP to make good use unequal size links without overloading the lower speed link Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 7

Load Balancing Making good use of expensive links simply by adjusting IGP metrics can Load Balancing Making good use of expensive links simply by adjusting IGP metrics can be a frustrating exercise! Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 8

Overlay Motivation Separate Layer 2 Network (Frame Relay or ATM) “The use of the Overlay Motivation Separate Layer 2 Network (Frame Relay or ATM) “The use of the explicit Layer 2 transit layer gives us very exacting control of how traffic uses the available bandwidth in ways not currently possible by tinkering with Layer 3 -only metrics. ” Mike O’Dell UUnet, November 17, 1996 Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 9

The Overlay Solution L 3 L 2 L 2 L 3 L 3 L The Overlay Solution L 3 L 2 L 2 L 3 L 3 L 3 L 3 Physical Logical • Layer 2 network used to manage the bandwidth • Layer 3 sees a complete mesh Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 10

Overlay Drawbacks • Extra network devices (cost) • More complex network management Two-level network Overlay Drawbacks • Extra network devices (cost) • More complex network management Two-level network without integrated NM Additional training, technical support, field engineering • IGP routing doesn’t scale for meshes Number of LSPs generated for a failed router is O(n 3); n = number of routers Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 11

Traffic Engineering & MPLS + Router ATM Switch or = MPLS Router ATM MPLS Traffic Engineering & MPLS + Router ATM Switch or = MPLS Router ATM MPLS Router • MPLS fuses Layer 2 and Layer 3 • Layer 2 capabilities of MPLS can be exploited for IP traffic engineering • Single box / network solution Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 12

An LSP Tunnel R 8 R 3 R 4 R 2 R 5 R An LSP Tunnel R 8 R 3 R 4 R 2 R 5 R 1 R 6 R 7 Labels, like VCIs can be used to establish virtual circuits Normal Route R 1 ->R 2 ->R 3 ->R 4 ->R 5 Tunnel: R 1 ->R 2 ->R 6 ->R 7 ->R 4 Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 13

Comprehensive Traffic Engineering • Network design Engineer the topology to fit the traffic • Comprehensive Traffic Engineering • Network design Engineer the topology to fit the traffic • Traffic engineering Engineer the traffic to fit the topology Given a fixed topology and a traffic matrix, what set of explicit routes offers the best overall network performance? Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 14

The Traffic Engineering System Statistics Collection Traffic Analysis Traffic Engineering Design and Modeling CLI The Traffic Engineering System Statistics Collection Traffic Analysis Traffic Engineering Design and Modeling CLI TE Tunnel Router Network Traffic Eng. © 1999, Cisco Systems, Inc. Configuration Traffic Engineering Tools Cisco Systems 15

Topology Approaches to Traffic Engineering Comprehensive for TE Premium Flows Tactical for Premium Flows Topology Approaches to Traffic Engineering Comprehensive for TE Premium Flows Tactical for Premium Flows Tactical TE Type of Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 16

Tactical Traffic Engineering • Links not available Infrastructure doesn’t exist Lead times too long Tactical Traffic Engineering • Links not available Infrastructure doesn’t exist Lead times too long • Failure scenarios • Unanticipated growth and shifts in traffic Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 17

Tactical TE An Example Major US ISP Ø New web site appears Within weeks Tactical TE An Example Major US ISP Ø New web site appears Within weeks becomes the largest traffic source on their network One of their Po. Ps becomes completely congested Ø Once the problem was identified TE tunnels were established to route away any traffic passing through that Po. P, but not destined or sourced there Congestion was completely resolved in 5 minutes Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 18

System Block Diagram Traffic Engineering Control Path Selection TE Topology Database RSVP TE Link System Block Diagram Traffic Engineering Control Path Selection TE Topology Database RSVP TE Link Adm Ctl IS-IS/OSPF Routing Flooding Forwarding Engine Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 19

TE Tunnel Attributes • Bandwidth • Setup & Holding priorities Used for Admission Control TE Tunnel Attributes • Bandwidth • Setup & Holding priorities Used for Admission Control • Resource class affinity Simple policy routing • Path Options Input to route selection Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 20

LSP Tunnel Setup R 9 R 8 R 3 R 4 R 2 Pop LSP Tunnel Setup R 9 R 8 R 3 R 4 R 2 Pop R 5 R 1 32 49 17 R 6 R 7 22 Setup: Path (R 1 ->R 2 ->R 6 ->R 7 ->R 4 ->R 9) Tunnel ID 5, Path ID 1 Reply: Communicates Labels and Label Operations Reserves bandwidth on each link Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 21

Multiple Parallel Tunnels • Automatically load shared • Weighted by bandwidth to nearest part Multiple Parallel Tunnels • Automatically load shared • Weighted by bandwidth to nearest part in 16 • Traffic assigned by either Source-Destination hash Round robin Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 22

Automatic Load Balancing New York #1 New York #2 LSP Tunnel #1 Link #1 Automatic Load Balancing New York #1 New York #2 LSP Tunnel #1 Link #1 LSP Tunnel #2 Link #2 Stockholm London #1 Frankfurt London #2 Amsterdam Brussels Washington Traffic Eng. © 1999, Cisco Systems, Inc. LSP Tunnel #3 Link #3 Cisco Systems Paris Munich 23

Additional Features • Adjusting to failures Requires rapid notification • Adjusting to improvements • Additional Features • Adjusting to failures Requires rapid notification • Adjusting to improvements • Need to account for Global optimality Network stability Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 24

Protection Strategy Two pronged approach: • Local protection Repair made at the point of Protection Strategy Two pronged approach: • Local protection Repair made at the point of failure us to keep critical applications going Fast - O(milliseconds) Sub-optimal • Path protection An optimized long term repair Slower - O(seconds) Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 25

Local Protection via a Bypass Tunnel R 2 R 9 R 4 R 8 Local Protection via a Bypass Tunnel R 2 R 9 R 4 R 8 R 3 R 1 R 5 R 10 R 7 R 6 Bypass Tunnel Primary Paths Backup Paths Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 26

Path Protection R 2 R 9 R 4 R 8 R 3 R 1 Path Protection R 2 R 9 R 4 R 8 R 3 R 1 R 5 R 10 R 7 R 6 Primary Path Backup Path Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 27

Summary Traffic engineering provides the means to ØSave transmission costs ØAddress routing deficiencies ØAttack Summary Traffic engineering provides the means to ØSave transmission costs ØAddress routing deficiencies ØAttack tactical network engineering problems ØProvide better Qo. S Making sure resource are available Minimizing disruption Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems 28

Thank You Traffic Engineering © 1999, Cisco Systems, Inc. 29 Thank You Traffic Engineering © 1999, Cisco Systems, Inc. 29