MPLS Traffic Engineering George Swallow swallow@cisco.com Traffic Engineering © 1999, Cisco Systems, Inc What is Traffic Engineering Taking control of how traffic flows in your network in order to Improve overall network performance Offer premium services As 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 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 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 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 The “Fish” Problem a deficiency in IP routing R8 R3 R4 R2 R5 R1 R6 R7 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 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 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 Overlay Motivation Separate Layer Network (Frame Relay or ATM) “The use of the explicit Layer 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 The Overlay Solution L3 L3 L2 L3 L2 L2 L2 L3 L2 L3 L2 L3 L3 L3 L3 L3 L3 L3 Physical Logical • Layer network used to manage the bandwidth • Layer sees a complete mesh Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 10 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 Comprehensive for TE Premium Flows Tactical for Premium Flows Tactical TE Type of Traffic Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 16 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 New web site appears Within weeks becomes the largest traffic source on their network One of their PoPs becomes completely congested Once the problem was identified TE tunnels were established to route away any traffic passing through that PoP, but not destined or sourced there Congestion was completely resolved in minutes Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 18 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 • Resource class affinity Simple policy routing • Path Options Input to route selection Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 20 LSP Tunnel Setup R9 R8 R3 R4 R2 Pop R5 R1 32 49 17 R6 R7 22 Setup: Path (R1->R2->R6->R7->R4->R9) Tunnel ID 5, Path ID 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 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 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 • 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 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 R2 R9 R4 R8 R3 R1 R5 R10 R7 R6 Bypass Tunnel Primary Paths Backup Paths Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 26 Path Protection R2 R9 R4 R8 R3 R1 R5 R10 R7 R6 Primary Path Backup Path Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 27 Summary Traffic engineering provides the means to Save transmission costs Address routing deficiencies Attack tactical network engineering problems Provide better QoS 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 ... Systems, Inc Cisco Systems 11 Traffic Engineering & MPLS + Router ATM Switch or = MPLS Router ATM MPLS Router • MPLS fuses Layer and Layer • Layer capabilities of MPLS can be exploited for IP traffic... Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 26 Path Protection R2 R9 R4 R8 R3 R1 R5 R10 R7 R6 Primary Path Backup Path Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 27 Summary Traffic... completely resolved in minutes Traffic Eng © 1999, Cisco Systems, Inc Cisco Systems 18 System Block Diagram Traffic Engineering Control Path Selection TE Topology Database RSVP TE Link Adm Ctl IS-IS/OSPF