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Mole planning routes

Routing Algorithm

How Muti Metroo discovers and selects routes through the mesh.

Route Propagation (Flooding)​

Routes are propagated through the mesh using a flood-based algorithm:

  1. Exit agent advertises route

    • Sends ROUTE_ADVERTISE frame with CIDR
    • Includes metric (hop count) and TTL

  2. Transit agents forward advertisement

    • Increment hop count (metric)
    • Add own AgentID to SeenBy list
    • Forward to all connected peers

  3. Loop prevention

    • Don't forward to agents in SeenBy list
    • Discard if hop count > max_hops
    • Discard if TTL expired

  4. Route table update

    • Add/update route in local table
    • Trigger route subscribers (stream manager)

Route Selection (Longest-Prefix Match)​

When opening a stream, routes are selected using longest-prefix match:

  1. Filter: Find routes where CIDR contains destination IP
  2. Sort by prefix length: Longest prefix (most specific) wins
  3. Tiebreaker: If tied, select lowest metric (hop count)

Example​

Routes in table:

  • 1.2.3.4/32 (metric 3, via agent-a)
  • 1.2.3.0/24 (metric 2, via agent-b)
  • 0.0.0.0/0 (metric 1, via agent-c)

For destination 1.2.3.4:

  • All three match
  • /32 wins (longest prefix)
  • Route via agent-a

For destination 1.2.3.100:

  • 1.2.3.0/24 and 0.0.0.0/0 match
  • /24 wins (longer than /0)
  • Route via agent-b

For destination 8.8.8.8:

  • Only 0.0.0.0/0 matches
  • Route via agent-c (default route)

Route Expiration​

Routes have configurable TTL (default 5m):

  • If no ROUTE_ADVERTISE received within TTL, route expires
  • Exit agents re-advertise periodically (default 2m)
  • Ensures stale routes are removed

Triggering Advertisement​

Immediate advertisement can be triggered:

curl -X POST http://localhost:8080/routes/advertise

Useful after:

  • Configuration changes
  • Adding new exit routes
  • Network topology changes

Redundant Paths​

Multiple agents can advertise the same route:

  • All routes are stored in table
  • Lowest metric (hop count) is preferred
  • Provides automatic failover if primary path fails

Example:

  • Agent-A advertises 10.0.0.0/8 (metric 1)
  • Agent-B advertises 10.0.0.0/8 (metric 2)
  • Traffic goes via Agent-A (lower metric)
  • If Agent-A fails, traffic switches to Agent-B

Node Information​

Agents also advertise node metadata via NODE_INFO_ADVERTISE:

  • Agent ID and display name
  • Hostname and IP address
  • OS and architecture
  • Uptime

This enables the web dashboard to show mesh topology.