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Reducing the impact of IXP maintenance

Reducing the impact of IXP maintenance. Will Hargrave // LONAP will@lonap.net. What is an IXP?. A switched fabric for interconnecting networks BGP is the control plane for network operators to signal reachability

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Reducing the impact of IXP maintenance

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  1. Reducing the impact of IXP maintenance Will Hargrave// LONAP will@lonap.net

  2. What is an IXP? • A switched fabric for interconnecting networks • BGP is the control plane for network operators to signal reachability • What happens to production traffic when an IXP operator does maintenance?

  3. A typical IXP IXP Switches BGP Session 192.0.1.3 192.0.1.2 ISP router A ISP router B

  4. Maintenance IXP Switches BGP Session 192.0.1.3 192.0.1.2 ISP router A ISP router B

  5. Waiting for BGP holdtimers… Traffic blackholed here  BGP Session Where’s my peer? Where’s my peer? 192.0.1.3 192.0.1.2 ISP router A ISP router B

  6. 90 to 180 seconds later…. IXP Switches BGP Session Holdtimer expired Holdtimer expired 192.0.1.3 192.0.1.2 ISP router A ISP router B

  7. Improving the experience • In many cases, IXP switch maintenance causes 90seconds+ blackholing of production traffic • We are doing things the wrong way round! • Solution: • At the start of the maintenance window, tear down the control plane! • Wait for traffic to diminish (3-5minutes) • Now do your maintenance • How to tear down the control plane? Answer: L4 ACLs on IXP port!

  8. L4 ACLs on IXP entry DenyBGPv4e { if { source-address 5.57.80.0/22; protocol tcp; source-port 179; } then { deny; } } entry DenyBGPv4i { if { source-address 5.57.80.0/22; protocol tcp; destination-port 179; } then { deny; } } entry DenyBGPv6e { Your IXP subnet Block in both directions, otherwise sessions will re-establish Obviously repeat this for IPv6 too

  9. End • We tested this during two recent LONAP maintenances with success. • Questions? Comments? Will Hargrave will@lonap.net

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