05-protocol-stack.md

🧩 Protocol Stack

Every protocol that runs in the network and on which layer of the topology.

flowchart TB
    subgraph L7["📚 Layer 7 — Application / Management Plane"]
      SSH["SSH v2 (rsa 1024)"]
      SNMP["SNMP (ready)"]
      SYSLOG["Syslog (ready)"]
    end

    subgraph L4["🛡️ Layer 4 — Security & Translation"]
      NAT["NAT/PAT overload"]
      ACL["ACL 1 — permit 10.10.0.0/16"]
      PORT["Port Security + BPDU Guard"]
    end

    subgraph L3["🌐 Layer 3 — Routing"]
      OSPF["OSPF Area 0"]
      BGP["BGP (simulated)"]
      HSRP["HSRP v1"]
      STATIC["Static (ISP ↔ Core)"]
    end

    subgraph L2["🔌 Layer 2 — Switching"]
      VLAN["VLANs 10/20/30/40/50/60/99/100/150"]
      DOT1Q["802.1Q Trunk"]
      STP["PVST+ · PortFast · BPDU Guard"]
      EC["EtherChannel Po1 (active)"]
    end

    L7 --> L4 --> L3 --> L2

    classDef l7 fill:#0d9488,stroke:#0d9488,color:#fff;
    classDef l4 fill:#9333ea,stroke:#9333ea,color:#fff;
    classDef l3 fill:#2563eb,stroke:#2563eb,color:#fff;
    classDef l2 fill:#65a30d,stroke:#65a30d,color:#fff;

    class SSH,SNMP,SYSLOG l7;
    class NAT,ACL,PORT l4;
    class OSPF,BGP,HSRP,STATIC l3;
    class VLAN,DOT1Q,STP,EC l2;

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🗃️ Where each protocol lives

Protocol	Where it runs	Purpose
OSPF	CORE-R1, CORE-R2, DIST-SW1, DIST-SW2	Dynamic internal routing
BGP	CORE-R1, CORE-R2 ↔ ISP	Simulated external routing
HSRP	DIST-SW1, DIST-SW2	First-hop gateway redundancy
NAT/PAT	CORE-R1, CORE-R2	Internet address sharing
802.1Q	All trunks	VLAN tagging
PVST+	All switches	Per-VLAN spanning tree
PortFast	Access ports	Fast edge transition
BPDU Guard	Access ports	Stops rogue switches
EtherChannel	Access ↔ Distribution	Aggregated GigE uplinks
SSH v2	All managed devices	Encrypted management