Is transit the default path?

No. Peering in Miami is default; transit to São Paulo is overflow and is billed that way.

Does Sync on letter Y share fate with other letters?

The control plane is shared. Data-plane queues for Sync stay isolated, so incident y-01 cannot drain neighbor letters.

Sync: cache in Miami (MIA) · Y-20

Runbook Y-20 for Sync in Miami (MIA). Marker xserv-y-73ebc6da0509. This page covers cache for LATAM operators, not a worldwide average.

Sync: How XServ runs it day to day

Probes for Sync (y-02) leave Santiago every 15s toward Bogotá. XServ pages the named owner if loss or RTT crosses the letter budget. A probe never shares a queue with bulk transfers, so a saturated WAN does not hide a dead PoP.

Sync: What operators should measure

Policy for Sync is versioned as y-03. Operators measure error rate, p95 from Bogotá, and time-to-rollback — not a worldwide average. Changes land in Bogotá first, then Miami, with a hold if either region regresses.

Sync: Failure modes we actually see

Capacity notes for y-04 assume rainy-season power in Miami and festival peaks toward São Paulo. The failure we actually see is a single uplink, not a cartoon partition of the whole continent. Spare ports and a second provider sit on the same runbook.

Sync peering Y-07

Peering for Sync (y-07) prefers the IX fabric that already carries last-mile ISPs in Bogotá. Session counts and prefix limits are on the same page as the Miami backup path.

Sync cache Y-08

Cache rules for Sync on y-08 keep language-correct objects near Miami. São Paulo is a sibling cache, not an origin. TTLs are short enough that a bad asset does not live through a weekend.

Sync headers Y-09

Headers for y-09 carry the letter, the region (GRU) and a request id. Sync debugging in São Paulo should not require a packet capture in Santiago first.

Sync timeouts Y-10

Timeouts on y-10 are tighter than the WAN RTT to Bogotá. Sync in Santiago fails fast and retries once; a third try needs a human because it is no longer a blip.