MODULE M7 · ~40 MIN · CINEMATIC + CAMERA

Reading the
Wire.

The module that turns a 5G signalling trace from noise into a story. The Service Based Interface at protocol depth — why the core runs on HTTP/2, the REST resource model and URI shape, the CRUD methods and custom operations, the pseudo- and 3gpp-Sbi headers, the full status-code table, ProblemDetails, subscribe/notify, the SCP and SEPP, and graceful overload control — narrated and fully animated, with flowing packets and a cinematic camera.

HTTP/2SBIbinary · multiplexed

CRUD+RPCmethod on a URI

statustable2xx·3xx·4xx·5xx

ProblemDetailscause · invalidParams

EN·فاkaraoke subs

TS 29.500 V19.4.0 §5.2 · §6 · Table 5.2.7.1-1 · TS 29.501 V19.3.0 §4.4 · §4.6 · §4.8

▶ VIDEO · MODULE 7 · ~40 MIN

SBI — every message is a method on a URI

The player screen is a live animation stage — packets flow along the wire, request/response arrows fire, and the status codes light up exactly as the narration reads them. Karaoke subtitles in English, two subtitle modes, fullscreen.

Module 7 · 5G Core Masterclass · reading the wire

SBI Deep Dive: HTTP/2 → REST → status → ProblemDetails

0:00 / 0:00

☰

REFERENCE · THE SBI STRUCTURES

The M7 IE catalogue →

Every structure the video reads — the HTTP/2 message, the resource URI, the CRUD methods, the pseudo- and 3gpp-Sbi headers, ProblemDetails, the status codes, subscribe/notify and load control — clause-cited, searchable.

REFERENCE · THE M7 IE CATALOGUE

Every structure on the wire

Each SBI structure the video reads — its interface, direction, purpose and clause. Click any row to open its full breakdown. Filter to find any of them.

Structure	Interface	Dir	What it does	Clause

TS 29.500 V19.4.0 §5.2 · §6 · TS 29.501 V19.3.0 §4.4/§4.6/§4.8 · TS 29.510

REFERENCE · HTTP/2 · URI · METHODS · HEADERS · STATUS · PROBLEMDETAILS

The Service Based Interface, at protocol depth

Everything the video reads on the wire, as reference you can scan: the HTTP/2 transport, the URI shape, the service names, the CRUD methods, the pseudo- and 3gpp-Sbi headers, the full status-code table, ProblemDetails, and subscribe/notify. Cited to TS 29.500 V19.4.0 and TS 29.501 V19.3.0.

The transport — HTTP/2 on SBI (TS 29.500 §5.2)

Framing & streams

HEADERS frame (HPACK-compressed) + DATA frame(s) for the body.
Each request/response on a numbered stream; client streams are odd.
Multiplexing → no head-of-line blocking.

Control

WINDOW-UPDATE = flow control.
RST-STREAM = cancel one request, keep the connection.
One long-lived connection per NF pair.

Rules

Runs over TLS (Module 6).
HTTP/2 server push is NOT used (§5.2.5).
Connections precious; streams cheap.

The URI shape & the service names (TS 29.501 §4.4.1)

Part	What it is	Example
{apiRoot}	scheme ("http"/"https") + "://" + authority (host[:port])	https://smf.op.com
<apiName>	the service — read it, and you know the function + intent	nsmf-pdusession
<apiVersion>	"v" + the major version only (minor/patch stay compatible)	v1
<resourceUriPart>	the resource-specific path (+ custom-op name for RPCs)	sm-contexts/42
Common api-names		nnrf-nfm · nnrf-disc · namf-comm · nsmf-pdusession · nudm-sdm · nudm-ueau · nausf-auth · npcf-smpolicycontrol · nchf-convergedcharging

Methods → CRUD, and custom operations (TS 29.501 §4.6)

POST

create child (producer picks id) → 201 + Location
not idempotent

PUT

create/replace (consumer picks id)
idempotent

GET

read; never changes state
query params + Accept · ETag/If-Match

PATCH

partial update
Merge Patch / JSON Patch

DELETE

remove → 204 No Content
idempotent

custom op

POST …/{resource}/{custOpName}
the verbs CRUD can't express

Idempotency: GET · PUT · DELETE are idempotent (safe to retry); POST is not. This is exactly what decides safe retries under overload (§5.2.8).

The headers that matter — pseudo · standard · 3gpp-Sbi (TS 29.500 §5.2.2 / §5.2.3)

Pseudo & standard

:method :scheme :authority :path :status — the skeleton.
Content-Type: application/json · multipart/related · application/problem+json.
Location (after POST/PUT) · Accept (→406/415) · Retry-After · Allow · ETag/If-Match.
Authorization: Bearer — the OAuth JWT (Module 6).

3gpp-Sbi-* (the telecom headers)

Target-apiRoot — the real producer when :authority is a proxy.
Callback · Message-Priority · Sender-Timestamp · Max-Rsp-Time.
Routing-Binding/Binding — pin requests to one instance.
Discovery-* (delegated discovery) · Lci/Oci (load/overload).
Reserved chars (e.g. JSON) are percent-encoded.

HTTP status codes on SBI — verbatim (TS 29.500 Table 5.2.7.1-1)

Support: M mandatory · SS service-specific · N/A not used. Per HTTP method: DELETE · GET · PATCH · POST · PUT.

Status	DEL	GET	PATCH	POST	PUT	Meaning on SBI
200 OK	SS	M	SS	SS	SS	success with a body
201 Created	N/A	N/A	N/A	SS	SS	resource created (+ Location)
202 Accepted	SS	N/A	SS	SS	SS	accepted, finished asynchronously
204 No Content	M	N/A	SS	SS	SS	success, nothing to return (DELETE, notify)
307 Temporary Redirect	SS	SS	SS	SS	SS	go to another instance (overload)
308 Permanent Redirect	SS	SS	SS	SS	SS	resource moved permanently
400 Bad Request	M	M	M	M	M	malformed request / schema error
401 Unauthorized	M	M	M	M	M	authentication failed
403 Forbidden	M	M	M	M	M	authorized identity, not permitted
404 Not Found	M	M	M	M	M	resource does not exist
405 Method Not Allowed	SS	SS	SS	SS	SS	wrong verb (+ Allow header)
406 Not Acceptable	N/A	M	N/A	N/A	N/A	can't produce an accepted format
409 Conflict	N/A	SS	SS	SS	SS	state conflict / already exists
411 Length Required	N/A	N/A	M	M	M	Content-Length required
412 Precondition Failed	SS	SS	SS	SS	SS	If-Match failed (resource changed)
413 Content Too Large	N/A	N/A	M	M	M	body too big
415 Unsupported Media Type	N/A	N/A	M	M	M	format not supported (+ Accept-Patch)
429 Too Many Requests	M	M	M	M	M	rate-limit — slow down
500 Internal Server Error	M	M	M	M	M	generic server failure
501 Not Implemented	SS	SS	SS	SS	SS	method unsupported by the API
502 Bad Gateway	M	M	M	M	M	bad response via a proxy
503 Service Unavailable	M	M	M	M	M	overloaded/down (+ Retry-After)
504 Gateway Timeout	SS	SS	SS	SS	SS	proxy waited for the producer, gave up

ProblemDetails — the structured error body (TS 29.501 §4.8 · RFC 9457)

Standard fields

type — URI naming the problem kind.
title — short human summary.
status — the HTTP code, echoed in the body.
detail — explanation of this occurrence.
instance — URI of the specific occurrence.

3GPP extensions (the afternoon-savers)

cause — machine-readable application error code.
invalidParams — exactly which fields were wrong.
Content-Type: application/problem+json.
Lets a SEPP/SCP add error detail on errors it originates.

Subscribe/Notify — the async pattern (TS 29.501 §4.6.2)

Step	Who	What
①	consumer → producer	POST /subscriptions carrying its callbackUri → 201 Created + Location
②	producer → consumer	on the event, producer becomes a client: POST {callbackUri} (notification body)
③	consumer → producer	204 No Content — acknowledged
④	consumer → producer	DELETE /subscriptions/{id} — unsubscribe

Every SBI element — searchable (methods · headers · status · errors · flows)

Filter by name, code, or family — TRANSPORT · METHOD · HEADER · STATUS · FLOW.

Element	Family	Where	Clause	What it is

TS 29.500 V19.4.0 §5.2 · §6 · Table 5.2.7.1-1 · TS 29.501 V19.3.0 §4.4 · §4.6 · §4.8 — verbatim

The rule to remember: the 5G core is a web of REST resources, and every message is a method on a URI with a status in return. Read the api-name for the actor, the method + URI for the action, the status + ProblemDetails for the outcome, and the 3gpp-Sbi headers for the routing — and any trace in your career becomes a document you can read, not a puzzle you must solve.

Built from ETSI TS 129 500 V19.4.0 & TS 129 501 V19.3.0

QUIZ · 10 QUESTIONS

Reading-the-Wire mastery check

Questions and answers reshuffle every load. 70%+ to consider Module 7 done.

Reading theWire.