Airtel WAN topology and Netfilter paths - Mermaid chart

airtel_topology.js

---
config:
  theme: neo-dark
---
flowchart TB
 subgraph Header_Info["ISP A + B + C"]
    direction LR
        A_Biz["<b>ISP-A Airtel</b><br>GPON FTTH Static IPv4"]
        B_Biz["<b>ISP-B Purple</b><br>GPON FTTH Static IPv4 Bridge"]
        C_Biz["<b>ISP-C Airtel</b><br>5G / LTE Android"]
  end
 subgraph PPPoE_A["PPPoE Tunnel: pppoe-out1"]
        A_IPv4["Dynamic IPv4 / CGNAT: 122.100.10.10"]
        A_IPv6["IPv6 DHCPv6 Prefix Delegation: 2001:470:35:80c::/64"]
  end
 subgraph V100_Inside["VLAN encapsulation"]
        A_L1["Static IP / IPoE: 182.100.10.10"]
        PPPoE_A
  end
 subgraph ISP_A_Stack["ISP A: Nested Encapsulation"]
        V100["VLAN 100 tag"]
        V100_Inside
  end
 subgraph PPPoE_B["PPPoE-Tunnel: pppoe-out2"]
        B_L1["Static IPv4 / IPCP: 160.100.10.10"]
  end
 subgraph RB5009["MikroTik RB5009 router"]
    direction TB
        SFP["SFP+1: HSGQ ONU SFP"]
        E4["Ether4: RJ45"]
        USB["USB Port: Tether"]
        ISP_A_Stack
        PPPoE_B
        C_L1["NAT: 192.168.100.10"]
        Bridge["Bridge / LAN"]
  end
 subgraph Presentation_View["Multi-WAN Overview"]
    direction TB
        Header_Info
        RB5009
  end
    A_Biz --> SFP
    SFP -- MTU 1500 --> V100
    V100 --> A_L1
    A_L1 -- Encapsulation --> PPPoE_A
    B_Biz --> E4
    E4 -- MTU 1500 --> PPPoE_B
    C_Biz --> USB
    USB -- MTU 1500 --> C_L1
    A_L1 -- MTU 1500 --> Bridge
    A_IPv4 -- MTU 1480 --> Bridge
    A_IPv6 -- MTU 1480 --> Bridge
    B_L1 -- MTU 1480 --> Bridge
    C_L1 -- MTU 1500 --> Bridge

     A_Biz:::Business_Box
     B_Biz:::Business_Box
     C_Biz:::Business_Box
     A_IPv4:::Tunnel_Path
     A_IPv6:::IPv6_Path
     A_L1:::Tunnel_Path
     PPPoE_A:::Nest_L3
     V100:::VLAN_Frame
     B_L1:::Tunnel_Path
     SFP:::Hardware_Box
     E4:::Hardware_Box
     USB:::Hardware_Box
     PPPoE_B:::Dark_BG
     C_L1:::Tunnel_Path
     Bridge:::Hardware_Box
    classDef Tunnel_Path fill:#66bb6a,stroke:#1b5e20,stroke-width:2px,color:#fff
    classDef IPv6_Path fill:#42a5f5,stroke:#0d47a1,stroke-width:2px,color:#fff
    classDef VLAN_Frame fill:#455a64,stroke:#cfd8dc,stroke-width:2px,stroke-dasharray: 5 5,color:#fff
    classDef Hardware_Box fill:#37474f,stroke:#90a4ae,stroke-width:1px,color:#fff
    classDef Business_Box fill:#263238,stroke:#00e5ff,stroke-width:1px,stroke-dasharray: 2 2,color:#00e5ff
    classDef Dark_BG fill:#102027,stroke:#37474f,stroke-width:2px,color:#fff
    classDef Nest_L1 fill:#263238,stroke:#455a64,stroke-width:1px,fill:#263238,stroke:#455a64,stroke-width:1px
    classDef Nest_L2 fill:#37474f,stroke:#455a64,stroke-width:1px
    classDef Nest_L3 fill:#455a64,stroke:#546e7a,stroke-width:1px
    style PPPoE_A color:#fff
    style V100_Inside color:#fff
    style ISP_A_Stack color:none
    linkStyle 0 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 1 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 2 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 3 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 4 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 5 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 6 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 7 stroke:#78909c,stroke-width:2px,fill:none
    linkStyle 8 stroke:#00bcd4,stroke-width:4px,fill:none
    linkStyle 9 stroke:#ffeb3b,stroke-width:4px,fill:none
    linkStyle 10 stroke:#42a5f5,stroke-width:4px,fill:none
    linkStyle 11 stroke:#f44336,stroke-width:4px,fill:none
    linkStyle 12 stroke:#9c27b0,stroke-width:4px,fill:none

netfilter_path.js

graph TD

%% ENTRY
LAN[LAN Clients] --> WANIN[WAN Interfaces<br/>vlan100<br/>pppoe-out1<br/>pppoe-out2<br/>lte1]

%% FIREWALL PIPELINE
WANIN --> RAW[RAW Table<br/>early drop]
RAW --> CONNTRACK[Connection Tracking<br/>Kernel state engine]

%% MANGLE
CONNTRACK --> MANGLE[Mangle PREROUTING<br/>PCC / DSCP / Routing Marks]

%% ROUTING
MANGLE --> ROUTE[Routing Decision<br/>main / policy tables]

%% FASTTRACK
ROUTE --> FASTTRACK{FastTrack?}

FASTTRACK -- yes --> FASTPATH[Fast Path<br/>skip firewall]
FASTTRACK -- no --> SLOWPATH[Slow Path<br/>traverse firewall]

FASTPATH --> NAT
SLOWPATH --> NAT

%% POSTROUTING
NAT[NAT srcnat / masquerade] --> POSTMANGLE[Mangle POSTROUTING]

%% QUEUES
POSTMANGLE --> QUEUE[Interface Queues<br/>CAKE / Queue Trees]

%% WAN EGRESS
QUEUE --> WAN1[ISP-A<br/>SFP+ VLAN100]
QUEUE --> WAN2[ISP-B<br/>Ether4 PPPoE]
QUEUE --> WAN3[ISP-C<br/>USB LTE]