Area Border Router (ABR) in OSPF — Role, LSA Types and Summarisation
An ABR connects an OSPF area to the backbone, keeps a separate LSDB per area, generates Type 3 LSAs, and…
OSPF Home / Category: Routing & Switching
Category: Routing & Switching
OSPF 
Routing What is CEF and How Does it Work on Cisco Router?
What is CEF? Cisco Express Forwarding (CEF) is a Layer 3 switching technology that offers high performance, low latency, and…
Routing & Switching Access Port vs Trunk Port — Difference and Configuration
Access port vs trunk port explained — the real difference is VLAN tagging, not device count. Includes Cisco configuration for…
DHCP APIPA — Why You Get a 169.254 Address and How to Fix It
A 169.254.x.x address means DHCP failed and Windows self-assigned an APIPA address. Here is how APIPA works, what it can…
BGP BGP Flapping — Causes, Route Dampening and How to Troubleshoot It
BGP flapping is a session or prefix repeatedly going up and down. Here are the real causes, the commands to…