Is transit the default path?

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

Does Backbone on letter B share fate with other letters?

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

Backbone: docs in Miami (MIA) · B-72

Runbook B-72 for Backbone in Miami (MIA). Marker xserv-b-5d8d91b9a041. This page covers docs for LATAM operators, not a worldwide average.

Backbone: A note on cost and transit

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

Backbone: Why it matters on this continent

Design for Backbone on letter B starts in São Paulo (GRU). Runbook b-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.

Backbone: How XServ runs it day to day

Probes for Backbone (b-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.

Backbone handoff B-05

Handoff from letter B Backbone into the rest of the platform uses the same request IDs as the gateway. Runbook b-05 names who accepts the ticket after São Paulo pages out. Santiago does not silently inherit the incident.

Backbone rollback B-06

Backbone peering B-07

Peering for Backbone (b-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.

Backbone cache B-08

Cache rules for Backbone on b-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.