Birds of a feather - network engineering
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A birds of a feather talk from Networkshop47 by: - Tony Hacche, senior network engineer, Jisc - Dave Tinkler, principal network engineer, Jisc
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Birds of a feather - network engineering
- 1. Birds of a feather - network engineering Tony Hacche, senior network engineer, Jisc Dave Tinkler, principal network engineer, Jisc
- 2. • Core Architecture Team (CAT) -Dave Tinkler -Tony Hacche • Network Engineering Group (NEG) -Dave Neller Introduction Network Engineering BoF2
- 3. • CAT -Lead engineers for Regional Networks - Tony – East Region, E Midlands Region and W Midlands region - Dave T – London, South, Thames Valley Network (TVN), Northern Ireland (NIR) -3rd line support • NEG -2nd line support -Managed Router Services What do we do ? Network Engineering BoF3
- 4. Network Engineering BOF Network Engineering BoF4 Network Surgery • Introduction • New Regional Infrastructure Test Rig • Questions for the NOC engineers • If time - Update on BGP Route Dampening Issue
- 5. • Testing Regional Infrastructure -Mixture of Ciena Carrier Ethernet Switches -8700, 5170, 39xx -Dedicated NMS -OneControl -Connected as a Regional Network to Janet -Out of Band access tested -G8032 Main Ring and Sub-Ring deployed Regional Network Test Rig Network Engineering BoF5
- 6. Regional Network Test Rig 6 Janet TESTRN AS 64668 Londa1-rbr1 RNEP Router Lond002-csw1 Londs1-csw1 Londs2-csw1 Londc1-csw1 Londd1-csw1 Londa1-csw1 Londb1-csw1 Lond001-csw1 Lond003-csw1 Lond004-csw1 Cust003 MRS Router Telehouse West Powergate Cust004 MRS Router Cust001 customer router Cust002 MRS Router Londb1-rbr1 RNEP Router G8032 Main Ring G8032 Sub Ring OneControl NMS Network Engineering BoF
- 7. • CE Switch at RNEP to CE Switch at Customer Site -Vlan to RNEP Router -Vlan to Customer Router -Multiple services eg IP and Netpath -Three customer types set up -Campus with two diverse connections -Site with single connection – MRS Router -Site with single connection – own router RN Test Rig - Circuits Network Engineering BoF7
- 8. Regional Network Test Rig - Circuits 8 Janet TESTRN AS 64668 Londa1-rbr1 RNEP Router Lond002-csw1 Londs1-csw1 Londs2-csw1 Londc1-csw1 Londd1-csw1 Londa1-csw1 Londb1-csw1 Lond001-csw1 Lond003-csw1 Lond004-csw1 Cust003 MRS Router Telehouse West Powergate Cust004 MRS Router Cust001 customer router Cust002 MRS Router Londb1-rbr1 RNEP Router G8032 Main Ring G8032 Sub Ring Campus LAN Network Engineering BoF
- 9. • Logical G8032 Rings -Two Main Rings -Customer -Inter-RNEP -One Sub-Ring -Customer RN Test Rig – Logical G8032 Rings Network Engineering BoF9
- 10. G8032 Logical Rings - Circuits 10 Positioning Root Protection Link (RPL) Londc1-csw1 Londd1-csw1 Londa1-csw1 Londb1-csw1 X RPL Inter-RNEP Circuit G8032 Rings Londs1-csw1 Londs2-csw1 Londc1-csw1 Londd1-csw1 Londa1-csw1 Londb1-csw1 X RPL Customer Circuit Logical G8032 Rings Network Engineering BoF
- 11. • Infrastructure Link Failure -No detectable packet Loss • Customer or RNEP Link failure -BGP remains up for 90s -Implemented BFD -Packet Loss dependent on BFD timers RN test Rig: Tests Network Engineering BoF11
- 12. Network Engineering Surgery - Questions
- 13. • Caused by multiple prefix announcements/withdrawals • Janet Global Transit Provider settings • Based on a Figure of Merit (FoM) -Each announcement/withdrawal FoM + 1000 -FoM = 6000 prefix is suppressed -Half life period (10 mins) FoM halved -Prefix unsupressed when FoM < 3000 or after 30 minutes -Started in Janet Jan ‘18 after core upgrades to 16.2R2.8 BGP Route Dampening Network Engineering BoF13
- 14. • Primary cause -JUNOS 15 and above BGP update distribution process separated from routing table update process • Why it affected Janet in particular -Confederated AS resilient model for regional networks -Increased numbers of announcements/withdrawals in the core -Selection of preferred advertisement not deterministic - dependent on router ID BGP Route Dampening - Causes Network Engineering BoF14
- 15. • Implemented Solution -Changed prefix preferences from Regional Network to the core to use local preference -Alternative Solution -Configure BGP update delay timer (‘feature’ introduced in JUNOS 15) BGP Route Dampening – Solution Network Engineering BoF15
- 16. Regional Network Topology 16 Regional Router Regional Router RNEP Router RNEP Router Core Router Core Router Peering Router Peering Router Janet Core Infrastructure Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Network Engineering BoF
- 17. Primary Link Fail 17 Regional Router Regional Router RNEP Router RNEP Router Core Router Core Router Peering Router Peering Router Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Withdrawal Withdrawal Withdrawal Withdrawal Withdrawal Withdrawal Withdrawal Network Engineering BoF Regional Router Regional Router RNEP Router RNEP Router Core Router Core Router Peering Router Peering Router Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Announcement AnnouncementAnnouncement Announcement Announcement Announcement Announcement
- 18. • Higher Local Preference • Shortest AS Path -Not in Confederation • Lowest Origin Code (IGP < EGP < unknown) -Not in Confederation • Lowest MED • Internal Routes (IGP/Static) BGP Route Selection - 1 Network Engineering BoF18
- 19. • Prefer EBGP over IBGP -Not in Confederation • Next Hop Lowest IGP Metric -Not in Confederation • Prefer currently active path -Not in Confederation • Lowest Router ID BGP Route Selection - 2 Network Engineering BoF19
- 20. Issue: Route Preference 20 Regional Router Regional Router RNEP Router Preference 3 RNEP Router Preference 4 Core Router Preference 1 Core Router Preference 2 Peering Router Peering Router Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Announcement AnnouncementAnnouncement Announcement Announcement Announcement Announcement Network Engineering BoF Regional Router Regional Router RNEP Router RNEP Router Core Router Core Router Peering Router Peering Router Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Announcement Announcement Announcement Preference1 Announcement Announcement Announcement Announcement
- 21. Issue: Old route announcement 21 Regional Router Regional Router RNEP Router RNEP Router Core Router Core Router Peering Router Peering Router Global Transit Core Router Core Router U N I V E R S I T YU N I V E R S I T Y AS 65XXX AS 65527 Announcement AnnouncementAnnouncement Announcement Announcement Announcement Announcement Network Engineering BoF
- 22. customerservices@jisc.ac.uk jisc.ac.uk Thank you Dave Tinkler Principal network engineer, Jisc 2 2 Network Engineering BoF Tony Hacche Senior network engineer, Jisc David Neller Network engineer, Jisc