Anycast: design in São Paulo (GRU) · A-49

Runbook A-49 for Anycast in São Paulo (GRU). Marker xserv-a-33a1406cbb4f. This page covers design for LATAM operators, not a worldwide average.

Anycast: Why it matters on this continent

Design for Anycast on letter A starts in São Paulo (GRU). Runbook a-01 keeps a single owner, a written rollback, and a traffic split that can be reversed without a global freeze. Neighbors in Santiago only take overflow after the local pool fails a health window.

Anycast: How XServ runs it day to day

Probes for Anycast (a-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.

Anycast: What operators should measure

Policy for Anycast is versioned as a-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.

Anycast rollback A-06

Rollback for a-06 is a documented command, not a hope. Transit is billed as backup while Anycast prefers peering in Santiago. If cost spikes, the runbook cuts overflow to Bogotá before touching customer prefixes.

Anycast peering A-07

Peering for Anycast (a-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.

Anycast cache A-08

Cache rules for Anycast on a-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.

Anycast headers A-09

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