gesh75 DC fabric upgrade
Do not use for campus stack upgrades or firewall HA failover. Not for optics swaps without a train change.
Procedure
- Read the release notes for the target train: EVPN, BFD, and VXLAN caveats. Lab the SMU on a spare leaf.
- Shift: one spine at a time, then border, then a canary leaf pair, then the rest. Never two spines.
- Abort criteria written before the window: BGP session count, EVPN route count, packet loss > 0.1% for 30s.
- Optics and FEC stay pinned. Do not "also replace QSFP" in the same window.
- Verify per device: control-plane, forwarding, then the next device.
window Sat 01:00-05:00
01:00 drain spine-1 confirm ECMP N-1
01:40 ISSU spine-1
02:10 un-drain watch 15m
abort if evpn type-2 delta > 1%
Anti-patterns
- Never upgrade both spines because "ISSU is hitless".
- Do not mix a code upgrade with a cabling change.
Safety
Abort is a first-class step. A failed canary stops the fleet.