What are directly connected routes and local routes, and when do they appear in the routing table?

Directly connected routes (C) appear when an interface with an IP (Internet Protocol) address is up/up — they represent the network the interface is on. Local routes (L) are /32 (IPv4) or /128 (IPv6) host routes for the router's own interface IPs.

Directly Connected (C):

• Created automatically when an interface has an IP address and is in up/up state
• Represents the network attached to that interface
• Uses the configured subnet mask (e.g., /24)
• Example: C 192.168.1.0/24 is directly connected, GigabitEthernet0/0

Local (L):

• Also created automatically alongside every connected route
• Represents the router's own IP address on that interface
• Uses a /32 mask (IPv4) or /128 prefix (IPv6) — matches only the exact IP
• Purpose: helps the router efficiently identify packets destined for itself vs. packets to forward
• Example: L 192.168.1.1/32 is directly connected, GigabitEthernet0/0

When they appear/disappear:

• Appear: When no shutdown is issued AND the interface reaches up/up status (Layer 1 + Layer 2 active)
• Disappear: When the interface goes down (cable unplugged, shutdown command, Layer 1 failure)

Requirements for an interface to be up/up:

• An IP address must be configured
• The interface must not be in shutdown state
• Layer 1 must be active (cable connected, link detected)
• Layer 2 must be active (protocol up — e.g., keepalives succeed)

Go deeper:

• Routing table (Wikipedia) — how connected/local entries fit the route-table model and when they install.