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Shadow Configurations : A Network Management Primitive

Shadow Configurations : A Network Management Primitive. Richard Alimi, Ye Wang, Y. Richard Yang Laboratory of Networked Systems Yale University. Configuration is Complex. “ 80% of IT budgets is used to maintain the status quo.”. “... human error is blamed for 50-80% of network outages.”.

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Shadow Configurations : A Network Management Primitive

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  1. Shadow Configurations:A Network Management Primitive Richard Alimi, Ye Wang, Y. Richard Yang Laboratory of Networked Systems Yale University

  2. Yale LANS / SIGCOMM 2008 Configuration is Complex “80% of IT budgets isused to maintain the status quo.” “... human error is blamed for 50-80% of network outages.” Source: Juniper Networks, 2008 Source: The Yankee Group, 2004

  3. Yale LANS / SIGCOMM 2008 Configuration is Complex “80% of IT budgets isused to maintain the status quo.” “... human error is blamed for 50-80% of network outages.” Source: Juniper Networks, 2008 Source: The Yankee Group, 2004 Why is configuration hard today?

  4. Yale LANS / SIGCOMM 2008 Simulation & Analysis Depend onsimplified models Network structure Hardware and software Limited scalability Hard to accessreal traffic Configuration Management Today Hardware Traffic iBGP SLAs Software VPNs OSPF ACLs eBGP TE

  5. Yale LANS / SIGCOMM 2008 Configuration Management Today Simulation & Analysis Depend onsimplified models Network structure Hardware and software Limited scalability Hard to accessreal traffic Test networks Can be prohibitively expensive Hardware Traffic iBGP SLAs Software VPNs OSPF ACLs eBGP TE

  6. Yale LANS / SIGCOMM 2008 Configuration Management Today Simulation & Analysis Depend onsimplified models Network structure Hardware and software Limited scalability Hard to accessreal traffic Test networks Can be prohibitively expensive Hardware Traffic iBGP SLAs Software VPNs OSPF ACLs eBGP TE Why are these not enough?

  7. Yale LANS / SIGCOMM 2008 Analogy with Programming Program Target System Programming

  8. Yale LANS / SIGCOMM 2008 Analogy with Programming Program Target System TargetNetwork Configs Programming Network Management

  9. Yale LANS / SIGCOMM 2008 Analogy with Databases STATE A INSERT ... UPDATE ... DELETE ... STATE B INSERT ... UPDATE ... DELETE ... Databases

  10. Yale LANS / SIGCOMM 2008 Analogy with Databases STATE A INSERT ... UPDATE ... DELETE ... STATE B INSERT ... UPDATE ... DELETE ... STATE A ip route ... STATE B ip addr ... STATE C router bgp ... STATE D router ospf ... ? Databases Network Management

  11. Yale LANS / SIGCOMM 2008 Enter, Shadow Configurations Key ideas Allow additional (shadow)config on each router In-network, interactiveshadow environment “Shadow” term fromcomputer graphics Hardware Traffic iBGP SLAs Software VPNs OSPF ACLs eBGP TE

  12. Yale LANS / SIGCOMM 2008 Enter, Shadow Configurations Hardware Traffic iBGP SLAs Software VPNs OSPF ACLs eBGP TE • Key ideas • Allow additional (shadow)config on each router • In-network, interactiveshadow environment • “Shadow” term fromcomputer graphics • Key Benefits • Realistic (no model)‏ • Scalable • Access to real traffic • Transactional

  13. Yale LANS / SIGCOMM 2008 Roadmap Motivation and Overview System Basics and Usage System Components Design and Architecture Performance Testing Transaction Support Implementation and Evaluation

  14. Yale LANS / SIGCOMM 2008 What's in the shadow configuration? Routing parameters ACLs Interface parameters VPNs QoS parameters System Basics Shadow config Real config

  15. Yale LANS / SIGCOMM 2008 What's in the shadow configuration? Routing parameters ACLs Interface parameters VPNs QoS parameters System Basics Shadow config Real config Real header marked “0” Shadow header marked “1”

  16. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Backup Path Verification Backup Primary

  17. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Backup Path Verification Send test packets in shadow

  18. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Backup Path Verification Disable shadow link X X

  19. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Backup Path Verification

  20. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Configuration Evaluation Video Server

  21. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Configuration Evaluation Video Server

  22. Yale LANS / SIGCOMM 2008 Example Usage Scenario:Configuration Evaluation Video Server Duplicate packets to shadow

  23. Yale LANS / SIGCOMM 2008 Roadmap Motivation and Overview System Basics and Usage System Components Design and Architecture Performance Testing Transaction Support Implementation and Evaluation

  24. Yale LANS / SIGCOMM 2008 Design and Architecture Management Configuration UI Control Plane OSPF BGP IS-IS Forwarding Engine FIB Interface0 Interface1 Interface2 Interface3

  25. Yale LANS / SIGCOMM 2008 Design and Architecture Management Configuration UI Control Plane OSPF BGP IS-IS Forwarding Engine Shadow-enabled FIB Shadow Bandwidth Control Interface0 Interface1 Interface2 Interface3

  26. Yale LANS / SIGCOMM 2008 Design and Architecture Management Configuration UI Control Plane Shadow Management OSPF BGP IS-IS Forwarding Engine Shadow-enabled FIB Shadow Bandwidth Control Interface0 Interface1 Interface2 Interface3

  27. Yale LANS / SIGCOMM 2008 Design and Architecture Management Configuration UI Control Plane Shadow Management OSPF BGP Commitment IS-IS Forwarding Engine Shadow-enabled FIB Shadow Bandwidth Control Interface0 Interface1 Interface2 Interface3

  28. Yale LANS / SIGCOMM 2008 Design and Architecture Management Debugging Tools Configuration UI Shadow Traffic Control FIB Analysis Control Plane Shadow Management OSPF BGP Commitment IS-IS Forwarding Engine Shadow-enabled FIB Shadow Bandwidth Control Interface0 Interface1 Interface2 Interface3

  29. Yale LANS / SIGCOMM 2008 Design and Architecture Management Debugging Tools Configuration UI Shadow Traffic Control FIB Analysis Control Plane Shadow Management OSPF BGP Commitment IS-IS Forwarding Engine Shadow-enabled FIB Shadow Bandwidth Control Interface0 Interface1 Interface2 Interface3

  30. Yale LANS / SIGCOMM 2008 Shadow Bandwidth Control Requirements Minimal impact on real traffic Accurate performance measurements of shadow configuration

  31. Yale LANS / SIGCOMM 2008 Shadow Bandwidth Control Requirements Minimal impact on real traffic Accurate performance measurements of shadow configuration Supported Modes Priority Bandwidth Partitioning Packet Cancellation

  32. Yale LANS / SIGCOMM 2008 Observation Content of payload may not important in many network performance testing scenarios Only payload size may matter Packet Cancellation

  33. Yale LANS / SIGCOMM 2008 Observation Content of payload may not important in many network performance testing scenarios Only payload size may matter Idea: only need headers for shadow traffic Piggyback shadowheaders on realpackets Packet Cancellation Piggybackedshadowheader

  34. Yale LANS / SIGCOMM 2008 Packet Cancellation Details Output interface maintains real and shadow queues Packet cancellation scheduling If real queue non-empty Grab real packet Piggyback shadow header(s)if available Else if shadow queue non-empty Send full shadow packet

  35. Yale LANS / SIGCOMM 2008 Commitment Objectives Smoothly swap real and shadow across network Eliminate effects of transient states due to config changes Easy to swap back

  36. Yale LANS / SIGCOMM 2008 Commitment Objectives Smoothly swap real and shadow across network Eliminate effects of transient states due to config changes Easy to swap back Issue Packet marked with shadow bit 0 = Real, 1 = Shadow Shadow bit determines which FIB to use Routers swap FIBs asynchronously Inconsistent FIBs applied on the path

  37. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases

  38. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases Distribute tags for each config C-old for current real config C-new for current shadow config 0: C-old 1: C-new 0 0 0 0 1 0 1 0 0 1 1 1 0

  39. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases Distribute tags for each config C-old for current real config C-new for current shadow config Routers mark packets with tags C-old 0 C-old C-old C-new C-old C-old C-new 0 1 0 1 C-old C-new C-old 0 1 C-new C-new C-old

  40. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases Distribute tags for each config C-old for current real config C-new for current shadow config Routers mark packets with tags Swap configs (tags still valid)‏ 0: C-new 1: C-old C-old 1 C-old C-old C-new C-old C-old C-new 0 1 0 1 C-old C-new C-old 0 1 C-new C-new C-old

  41. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases Distribute tags for each config C-old for current real config C-new for current shadow config Routers mark packets with tags Swap configs (tags still valid)‏ Remove tags from packets Resume use of shadow bit 1 0 1 0 1 0 1 0 0

  42. Yale LANS / SIGCOMM 2008 Commitment Protocol Idea: Use tags to achieve consistency Temporary identifiers Basic algorithm has 4 phases Distribute tags for each config C-old for current real config C-new for current shadow config Routers mark packets with tags Swap configs (tags still valid)‏ Remove tags from packets Resume use of shadow bit For more details, see paper 1 0 1 0 1 0 1 0 0

  43. Yale LANS / SIGCOMM 2008 Roadmap Motivation and Overview System Basics and Usage System Components Design and Architecture Performance Testing Transaction Support Implementation and Evaluation

  44. Yale LANS / SIGCOMM 2008 Implementation Kernel-level (based on Linux 2.6.22.9)‏ TCP/IP stack support FIB management Commitment hooks Packet cancellation Tools Transparent software router support (Quagga + XORP)‏ Full commitment protocol Configuration UI (command-line based)‏ Evaluated on Emulab (3Ghz HT CPUs)‏

  45. Yale LANS / SIGCOMM 2008 Static FIB300B pktsNo route caching • Static FIB • 300B pkts • No route caching • With FIB updates • 300B pkts @ 100Mbps • 1-100 updates/sec • No route caching

  46. Yale LANS / SIGCOMM 2008 Evaluation: Memory Overhead FIB storage overhead for US Tier-1 ISP

  47. Yale LANS / SIGCOMM 2008 Evaluation: Packet Cancellation • Accurate streaming throughput measurement • Abilene topology • Real transit traffic duplicated to shadow • Video streaming traffic in shadow

  48. Yale LANS / SIGCOMM 2008 Evaluation: Packet Cancellation • Limited interaction of real and shadow • Intersecting real and shadow flows • CAIDA traces • Vary flow utilizations

  49. Yale LANS / SIGCOMM 2008 Evaluation: Packet Cancellation • Limited interaction of real and shadow • Intersecting real and shadow flows • CAIDA traces • Vary flow utilizations

  50. Yale LANS / SIGCOMM 2008 Evaluation: Commitment • Applying OSPF link-weight changes • Abilene topology with 3 external peers • Configs translated to Quagga syntax • Abilene BGP dumps

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