SNMP vs. Telemetry

SNMP and streaming telemetry are the two main approaches in use today for getting operational data - interface counters, CPU load, optical power, and the rest - off a network device and into a monitoring system. They aren't interchangeable, and neither has fully replaced the other: most real networks run some mix of both. This guide covers how they actually differ - architecture, data modeling, transport, and the practical tradeoffs - and when each one makes sense. For SNMP's own internals specifically, see SNMP Fundamentals.

What each one is

SNMP (Simple Network Management Protocol), covered in depth in SNMP Fundamentals, is a request/response protocol dating to the late 1980s: a manager asks an agent for a specific value (or walks a subtree of values), the agent answers. Agents can also push unsolicited notifications - traps and informs - but the dominant usage pattern for ordinary metrics collection is polling: a monitoring system asking, on a fixed schedule, for the same set of OIDs over and over.

Streaming telemetry is a newer, broader term covering several related technologies - gNMI (gRPC Network Management Interface), NETCONF/YANG push subscriptions, and various vendor-specific equivalents - that share a common model: the network device pushes data to a collector continuously, or on a defined interval the device itself manages, rather than being asked for it repeatedly. Most of these build on YANG as the data modeling language and gRPC or NETCONF as the transport, rather than SNMP's own OID/MIB stack.

Pull vs. push: the core architectural difference

This is the single biggest distinction, and the one that drives most of the others. SNMP is fundamentally pull-based: the manager decides when to ask, and gets one answer per ask. To get a value every 10 seconds, the manager has to send a new request every 10 seconds - and this cost scales directly with the number of devices, the number of metrics per device, and how frequently you want updates. Polling 10,000 interface counters every 10 seconds across a large network is a genuinely significant, continuous load on both the polling system and the devices being polled, even though any individual request is cheap.

Streaming telemetry is push-based: a collector establishes one subscription describing what it wants (a set of YANG paths, a desired interval or a report-only-on-change policy) and the device then streams matching updates on its own, over a single long-lived connection, without the collector re-asking. This removes the repeated per-poll request/response overhead entirely and, for change-triggered subscriptions, can report a state change essentially immediately rather than waiting for the next poll cycle to notice it - a meaningful difference for anything latency-sensitive (link flaps, BGP session changes) where a 10- or 30-second polling interval is genuinely too slow.

Data modeling: OIDs and MIBs vs. YANG

SNMP's data is described by MIBs, defining a flat(ish) tree of numeric OIDs - see Understanding MIBs for the full detail. It's a mature, extremely widely implemented format, but it predates modern structured data practices: no native nested objects beyond simple tables, limited type system, and a module format (SMIv2 ASN.1) that's awkward to generate or validate programmatically compared to more modern schema languages.

Streaming telemetry's dominant data model is YANG, a considerably more expressive schema language supporting nested structures, richer types, and - notably - the same YANG models are increasingly used for both reading state (telemetry) and writing configuration (via NETCONF/RESTCONF), giving a single consistent schema across both jobs rather than SNMP's split between a MIB for reading and a completely separate CLI or API for configuration changes.

Transport and encoding

SNMP runs over UDP (see Transport in SNMP Fundamentals for why), with its own ASN.1 BER binary encoding on the wire. Streaming telemetry implementations vary: gNMI runs over gRPC, which itself runs over HTTP/2 and TCP, typically encoding payloads in Protocol Buffers (a compact, schema-driven binary format) rather than SNMP's ASN.1. NETCONF-based telemetry instead typically carries XML payloads over SSH. In both cases, the underlying transport is a persistent, connection-oriented session rather than UDP's one-off, connectionless packets per request - which is part of what makes reliable, ordered streaming of continuous updates practical in a way it genuinely isn't on top of plain SNMP.

Scalability and performance

At small scale the difference is mostly academic. At the scale of a large enterprise or service-provider network - tens of thousands of interfaces, sub-second visibility requirements - it stops being academic: SNMP polling's cost grows with polling frequency times device count times metrics per device, and pushing that frequency down toward sub-second intervals for a large fleet can genuinely overwhelm both the polling system and, in some cases, the devices themselves (SNMP agents on constrained hardware aren't always built to handle extremely high query rates gracefully). Streaming telemetry's push model, particularly with change-triggered rather than purely interval-based subscriptions, decouples update frequency from this kind of brute-force polling cost, which is the main reason it's seen the most adoption specifically in large-scale, high-frequency-visibility environments rather than smaller networks where SNMP polling every 30-60 seconds is perfectly adequate.

Security

Modern streaming telemetry implementations (gNMI over gRPC, NETCONF over SSH) are built on transport-layer security (TLS or SSH) by default, with no equivalent to SNMP's old plain-text community-string era to worry about. SNMP, as covered in SNMP versions and in full in the SNMPv3 guide, has real security too - v3's authenticated, encrypted USM model is not meaningfully weaker than what telemetry transports provide - but it's opt-in and has to be deliberately configured, whereas most telemetry stacks assume an authenticated, encrypted transport from the start. A huge amount of real-world SNMP deployment is still on v2c with a plain-text community string specifically because it's simpler to stand up, which is a security tradeoff worth being honest about even though SNMPv3 itself closes the gap.

Tooling and ecosystem maturity

SNMP's advantage here is sheer ubiquity and age: it's supported on essentially every piece of network hardware made in the last three decades, from enterprise routers down to printers and UPS units, with a vast, mature ecosystem of tooling - net-snmp, and monitoring platforms like Zabbix, LibreNMS, PRTG, and Nagios, all built around it from the start (see Using net-snmp). Streaming telemetry support is concentrated in newer, higher-end equipment - core routers and switches from the last several years, mainly - and the tooling ecosystem, while growing quickly (OpenConfig, Telegraf's gNMI input, various time-series backends), is considerably less universal and less mature than SNMP's. A fleet with older or lower-end hardware mixed in essentially has to keep SNMP in the picture regardless of how much it might prefer telemetry for the gear that does support it.

Pros and cons

SNMP - pros: near-universal device support, including old and low-end hardware; simple to stand up for basic polling; enormous, mature tooling ecosystem; a huge existing base of documented MIBs covering decades of hardware. SNMP - cons: polling overhead that scales poorly at very high frequency or very large fleet size; no efficient native push/streaming model (traps/informs exist but aren't a substitute for structured, subscription-based telemetry); a dated data-modeling format; meaningful security requires deliberately configuring v3 rather than getting it by default.

Streaming telemetry - pros: push-based, near-real-time updates, especially for change-triggered data; decouples update frequency from brute-force polling cost, scaling much better at very high frequency or very large fleet size; a modern, more expressive data model (YANG) shared with configuration management; secure transport by default. Streaming telemetry - cons: support concentrated in newer, higher-end hardware, not universal across an existing fleet; more involved initial setup (subscriptions, YANG model familiarity) than firing off an SNMP GET; a less mature, more fragmented tooling ecosystem than SNMP's decades-old one; multiple competing implementations (gNMI, NETCONF push, vendor-specific variants) rather than one single widely-agreed standard the way SNMP effectively is.

Which to use when

In practice this isn't usually an either/or choice. SNMP remains the pragmatic default for broad device coverage, infrequent-to-moderate polling intervals, and any hardware that doesn't support telemetry at all - which, across a typical mixed-age network, is still a meaningful share of the fleet. Streaming telemetry earns its added setup cost specifically where SNMP's polling model genuinely struggles: very high-frequency or near-real-time visibility requirements, very large device counts, or environments already standardizing on YANG-based configuration management where reusing the same data model for monitoring is a real win. Many networks run both side by side - SNMP for broad, general-purpose monitoring across the whole fleet, streaming telemetry layered on top for the specific high-value, high-frequency use cases (backbone interfaces, BGP sessions) where it earns its keep - rather than treating the choice as a wholesale replacement of one for the other.