DOCSEARCHbyAlgolia
Submit Docs

Terragraph Developer and Runbook Documentation

website·Indexed 34 days ago

https://terragraph.com/

Technical documentation for Terragraph, a 60 GHz spectrum technology for high-speed internet delivery. Includes developer guides on MAC/PHY specifications, VPP implementation, routing layers, and driver stacks, as well as runbooks for network planning, deployment, monitoring, and troubleshooting.

Tokens
89.9K
Snippets
247
Records
588
Agent score
71%

What's inside Terragraph

  1. Overview of Terragraph Scan Architecture

    The ScanApp is responsible for initiating scans on nodes and collecting measurement results. The ScanScheduler uses a graph coloring algorithm to schedule scans periodically and in parallel, while SchedulerApp manages slot scheduling. The minion acts as a pass-through, forwarding controller commands to the driver and returning results to the controller.

  2. Overview of Terragraph API Service

    The api_service provides a REST API for the E2E controller and NMS aggregator. It acts as a translation layer that converts HTTP/JSON requests into ZMQ/Thrift calls and returns JSON-encoded responses. The service is implemented in C++ using the Proxygen web server.

  3. Overview of PTP and SyncE in Terragraph

    Terragraph implements IEEE 1588v2 (Precision Time Protocol, PTP) and Synchronous Ethernet (SyncE) to meet cellular backhaul synchronization requirements. In telecom networks, PTP is typically used for phase synchronization, while SyncE is used for frequency synchronization. According to ITU G.8273.2 and G.8273.3, the PTP clock's frequency reference is provided by the physical layer based on ITU G.8262 EEC-Option 1 (SyncE).

  4. Overview of E2E Controller High Availability

    The E2E controller implements high availability using a primary-backup protocol based on the Binary Star Pattern. Two controllers (peers) are deployed on separate machines. If the primary controller fails, the backup assumes control of the Terragraph network. Failover is triggered when a minion (client) experiences a connection timeout with the current controller and attempts to connect to the alternative peer.

  5. Overview of Terragraph Routing Layer

    Terragraph implements a wireless mesh network using distribution nodes (DN) and client nodes (CN). One or more DNs act as points of presence (POP) with fiber connectivity to the Internet. The routing layer is powered by Open/R, which uses a distributed, eventually-consistent key-value store (KvStore) to implement a link-state routing protocol. It computes routes using a weighted shortest-paths algorithm and employs equal-cost multi-path routing (ECMP) when multiple best paths exist.

  6. Overview of Terragraph scan types

    Scans in Terragraph are used to measure SNR and interference, refine beam angles, and debug underperforming links. They are categorized as either 'wide' (evaluating the entire beam range) or 'selective' (evaluating a narrow range to reduce interference).

  7. Overview of Terragraph (TG) System Architecture

    Terragraph is a 60GHz, multi-node wireless Software Defined Network (SDN) designed as a distribution-level network to augment fiber optic networks. It functions as a high-speed backbone ("wireless fiber") providing gigabit speeds, primarily operating in Line-Of-Sight (LOS) conditions. The network consists of Layer 3 (L3) routers that use the Open/R protocol for routing and a modified IEEE 802.11 DMG PHY layer with a slimmed-down MAC layer for over-the-air communication. It utilizes phased array antennas and beamforming to establish communication links (micro-routes) over distances exceeding 250 meters.

  8. Overview of Terragraph wireless technology

    Terragraph is a wireless technology designed for Internet Service Providers (ISPs) to deploy gigabit connectivity in markets where trenching fiber is difficult or cost-prohibitive. It provides fiber-like speeds using the unlicensed 60 GHz spectrum, allowing for faster and more efficient network deployment.

  9. Overview of Terragraph E2E Cloud Services

    The Terragraph cloud suite is typically deployed as Docker services within a Docker Swarm. The E2E services provide the core functionality required to initialize and operate a network:

  10. Overview of Terragraph Timing Synchronization Methods

    Terragraph requires absolute time and phase synchronization to maintain the time division duplex (TDD) slot architecture and derive superframe numbers for scheduling. There are two primary methods for achieving this:

    1. GPS: Co-located GPS receivers provide precise timing. To minimize dependence on clear sky visibility, Terragraph uses 'single satellite mode' (time-only mode), as the nodes are stationary and only time is the unknown variable.
    2. Over-the-Air (OTA) Sync: A single timing source synchronizes downstream nodes over a limited number of hops using high-resolution TSF (HTSF) messages. This uses nanosecond Tx/Rx timestamps (~6ns accuracy) and a two-way exchange to compensate for propagation delay.

  11. PTP Hardware Requirements for Distributed PTP-TC

    To support the distributed PTP-TC architecture, the following hardware requirements are mandatory:

    • Hardware timestamping for all 1G or 10G interfaces with at least 40 ns accuracy.
    • Timestamping must be applied to all packets with EtherType 0x88F7 or UDP destination ports 319 or 320 (after removing encapsulation).
    • The PTP clock used for timestamping must be syntonized to a supported reference (e.g., GPS, HTSF).

    NXP Processor Support:

    • LS1012: No hardware PTP timestamping support.
    • LS1023/1026/1041: Supports 2-step operation.
    • LS1048/1088: Supports 1-step operation (superset of 2-step).

  12. Terragraph Routing Layer Architecture

    Terragraph utilizes Open/R as its routing platform. It employs a distributed, eventually-consistent key-value store called KvStore to disseminate routing adjacencies and network prefixes across the network to implement a link-state routing protocol. Every Terragraph node runs an openr process.