Now building — Phase 0 Standards Map dropping first

Protocols &
Standards,
Finally Explained.

A visual learning platform for engineers who are tired of reading 800-page specs. Concept → Flow → Reality. Telecom, networking, security — all mapped, all clear.

Explore the Library See the Standards Map →
6
Standards bodies mapped
3GPP · IETF · ITU-T · ETSI · GSMA · IEEE
3
Content types, not just articles
Protocol Cards · Visual Flows · Deep Dives
4
Target audiences
Telecom · Network · Cloud · Technical Mgmt
Free
Always & forever
Open knowledge, no paywalls on fundamentals
OSI REFERENCE MODELprotostack.io/osi
L7
Application
HTTP · SIP · DNS · DIAMETER
L6
Presentation
TLS · ASN.1 · codec
L5
Session
SDP · RTP · NetBIOS
L4
Transport
TCP · UDP · SCTP · QUIC
L3
Network
IP · GTP · BGP · MPLS
L2
Data Link
Ethernet · 802.11 · PDCP
L1
Physical
5G NR · LTE · Fiber · DSL
3GPP Rel-18 RFC 3261 · SIP GTP-U · GTP-C IEEE 802.11ax QUIC · RFC 9000 NGAP · TS 38.413 ITU-T G.8032 Diameter · RFC 6733 SCTP · RFC 4960 PFCP · TS 29.244 ITU-T Y.1731 BGP · RFC 4271 VoLTE · IMS IEEE 802.1Q VLAN TLS 1.3 · RFC 8446 GSMA SGP.22 eSIM 3GPP Rel-18 RFC 3261 · SIP GTP-U · GTP-C IEEE 802.11ax QUIC · RFC 9000 NGAP · TS 38.413 ITU-T G.8032 Diameter · RFC 6733 SCTP · RFC 4960 PFCP · TS 29.244 ITU-T Y.1731 BGP · RFC 4271 VoLTE · IMS IEEE 802.1Q VLAN TLS 1.3 · RFC 8446 GSMA SGP.22 eSIM
// what is protostack

Not a blog. A mental model library.

Three content types, built around how engineers actually learn — not how spec bodies write.

🃏
Protocol Cards

Every protocol gets a consistent card: the problem it solves, where it lives in the stack, its key entities, a 5–12 step message flow, and what breaks — plus how to detect it. Fast to read. Easy to recall.

What problem it solves OSI placement Message flow Failure modes KPIs + logs
🔀
Visual Flows

Ladder diagrams, packet journey maps, and architecture canvases. Built in a consistent diagram kit so every visual speaks the same language. ProtoStack's signature asset — memorable, shareable, reusable.

Call flows Packet journeys Architecture maps "What happens when…"
📐
Deep Dives

Spec-to-reality. What the standard says vs what actually gets deployed. Failure analysis, roaming edge cases, troubleshooting playbooks. For engineers who need more than surface level.

Real deployments Spec vs reality Troubleshooting Roaming + IPX

// standards ecosystem — phase 0

Who produces what — and why it matters.

Before you understand any protocol, you need to know who wrote it, how it evolved, and how it connects to everything else. This is the map before the journey.

3GPP
3rd Generation Partnership Project
Telecom

Defines cellular networks end-to-end: radio access, core network, IMS, roaming interfaces. Every LTE, VoLTE, and 5G spec lives here. Releases are versioned (Rel-8 → Rel-18+).

Outputs: TS (Technical Spec) · TR (Technical Report) · CRs
IETF
Internet Engineering Task Force
Internet

Open, volunteer-driven. Produces RFCs that define the internet's protocol stack — TCP, DNS, SIP, QUIC, TLS, BGP, SCTP. Many telecom protocols build on IETF foundations.

Outputs: RFC (Request for Comments) · Internet-Drafts
ETSI
European Telecom Standards Institute
European

European partner of 3GPP. Publishes EN/ES standards for telecom equipment, NFV, MEC, and security. Also houses the NFV ISG (Network Functions Virtualisation Industry Spec Group).

Outputs: EN · ES · GS (Group Spec) · GR (Group Report)
GSMA
GSM Association
Operators

The operators' club. Produces implementation specs (IR docs) and PRDs for inter-operator topics: roaming, eSIM, fraud, IPX connectivity. Where operators agree on how to actually implement 3GPP specs together.

Outputs: IR.xx (Inter-PLMN Roaming) · PRD · SGP (eSIM)
ITU-T
ITU Telecom Standardization Sector
UN Body

The UN's telecom standards arm. Governs transport (G-series), OAM (Y-series), SDH/SONET, and international interconnect policy. Essential for transport and OAM engineers.

Outputs: Recommendations (G. / Y. / X. / H. series)
IEEE
Inst. of Electrical & Electronics Engineers
L1–L2

Defines the physical and data link layers: Ethernet (802.3), Wi-Fi (802.11), VLANs (802.1Q), Time-Sensitive Networking (TSN). The foundation everything else runs on.

Outputs: IEEE Standards (802.x · 1588 · 1914)

// content library preview

What an explainer actually looks like.

Every piece follows a consistent structure. You always know what you're getting.

TYPE A
Protocol Card

A consistent 5-section card for any protocol. Read one, know how to read all of them.

PROTOCOL: SCTP · RFC 4960
PROBLEM : Multi-homing + no HOL blocking
LAYER : L4 Transport (between TCP & UDP)
ENTITIES: Association · Streams · Chunks

── CORE FLOW ──────────────────────────
1. INIT → INIT-ACK (4-way cookie handshake)
2. COOKIE-ECHO → COOKIE-ACK
3. Association established (multi-path)
4. DATA chunks sent per stream
5. SACK acknowledges individually

── FAILURE MODES ──────────────────────
! INIT collision → tie-breaking via tags
! Path failure → HB probing + failover
! KPI: hbAckTimeout, pathFailures
TYPE B
Visual Flow — Ladder Diagram

Real call flows from the spec, annotated with actual field values. SIP IMS registration:

UE
P-CSCF
REGISTER sip:ims.mnc001…
P-CSCF
I-CSCF
REGISTER (+ Via, Route)
I-CSCF
HSS
Cx: UAR →
← UAA (S-CSCF name)
TYPE C
Deep Dive — Spec to Reality

What the standard says. What operators actually deploy. Where they diverge.

── EXAMPLE: LTE Roaming (S8 vs S9) ───

SPEC SAYS:
 S8 = direct GTP between HPLMN + VPLMN
 S9 = policy coordination via Diameter

REALITY:
 ! Most operators use LBO (Local Breakout)
 ! HR roaming adds latency via GTP tunnel
 ! IPX intermediaries inject policy nodes
 ! GSMA IR.88 overrides 3GPP defaults

TROUBLESHOOT:
  S6b auth fail → check AAA realm routing
  PGW selection → DNS NAPTR order matters
TYPE D
Standards Guide — How to Read Specs

The spec ecosystem explained before you read any individual spec. Phase 0 content.

── HOW TO READ A 3GPP TS ───────────────

SCOPE : Chapter 1 — read this first
DEFS : Chapter 3 — abbreviations
ARCH : Chapter 4 — reference model
FLOWS : Chapter 6+ — the real content

── NAVIGATION TRICKS ───────────────────
"void" = intentionally blank section
[R17] tag = Release 17 addition
Annex = informative (optional reading)
CRs show what changed between releases

! Always verify which Release you need

// browse by domain

Everything protocol-driven, covered.

Organized how engineers think — not how spec bodies name things. Telecom is the strong differentiator. Everything else fills in around it.


// our method

Concept → Flow → Reality.

Every explainer follows the same spine. Predictable structure. Reliable depth. No island articles.

01
Primary source first

We read the actual TS, RFC, or IR. Not a blog post about it. Not a vendor whitepaper. The real spec — then we figure out what matters.

02
Build the mental model

What problem does this protocol solve? What entities exist? How do they talk? We frame it before we flow it. No diagram without a model first.

03
Flows with real packet fields

Ladder diagrams with actual field values — not generic arrows between boxes. Wireshark-level fidelity, readable at a glance.

04
Spec vs reality — what actually breaks

The gap between what the spec says and what operators deploy. Failure modes, troubleshooting hints, and the KPIs that catch problems early.

05
Connected to the ecosystem

Every protocol links to what sits above and below it, what standards body owns it, and what real-world function it serves. No island explainers.

protocol card structure
📌 What problem it solves
The "why" before the "what"
Concept
↓ then
🗺️ Stack placement + entities
OSI layer · roles · interfaces
Model
↓ then
🔀 Message flow — 5–12 steps
Ladder diagram, real field values
Flow
↓ then
⚡ Spec vs deployment reality
What operators actually do
Reality
↓ finally
🔍 Failure modes + KPIs
How to detect it · how to fix it
Ops

// weekly digest

One protocol.
Every Thursday.

A new explainer every week — protocol card, visual flow, or deep dive. Written for engineers who need to actually understand it, not just know it exists.

Free forever No spam Unsubscribe anytime
✓ No paywalls on fundamentals  ·  ✓ Telecom-first  ·  ✓ Unsubscribe any time