Dynamic routing with OSPF (FRRouting)
You run OSPF on several routers with FRRouting, manage areas, costs and convergence, and watch the network heal itself when a link breaks.
Level 301 · 19 lessons · 15 practice labs
Lessons
OSPF basics
- OSPF concepts: link state, LSAs, SPF
- Setting up single-area OSPF
- Neighbour states and hello/dead timers
- DR and BDR election
- Cost and path selection
- Short task: get full reachability on three routers with OSPF
Multi-area OSPF
- Areas and the backbone area
- LSA types and reading the link-state database
- Stub and NSSA areas
- Summarising at the area border
- Redistributing static routes into OSPF
- Short task: build a two-area network and summarise it
Operations and security
- OSPF authentication
- Passive interfaces: no hellos towards user networks
- Fast failure detection with BFD
- OSPF troubleshooting: the adjacency will not form
- IPv6 routing with OSPFv3
- Short task: find why an adjacency will not come up
Wrap-up
- Capstone: design OSPF for a campus and test an outage live
Practice labs
- No adjacency: wrong area number: Find the area mismatch stopping OSPF between two Kuzey Logistics routers, fix it and show the neighbour reaching Full with "show ip ospf neighbor".
- A neighbour stuck in ExStart: Prove with a packet capture why an adjacency is stuck in ExStart even though hellos flow (an MTU difference), make both sides consistent and show the LSDBs synchronising.
- Three routers, three silent faults: Find the timer, network-type and passive-interface faults hidden across Blue Harbour Cargo’s three-router OSPF network, fix them and document with a ping table that every subnet is reachable from every router.
- Traffic takes the slow link: Fix the OSPF cost that sends branch traffic over the backup link instead of the fast one, and prove the new path with traceroute.
- Gigabit and 10-gigabit cost the same: Set a consistent cost scheme on all routers so links that look equal because of the reference bandwidth are told apart, and show it with the costs in the routing table.
- Out one way, back another: Expose with traceroutes in both directions the asymmetric path confusing Atlas Clinic’s firewall, rework the costs so traffic returns the way it left, and prove it.
- Turn the branch into a stub area: Make a small branch area a stub to shrink its router’s LSDB, and show that a default route has replaced the external routes.
- One summary instead of a hundred routes: Summarise the given address block on the area border router, show in numbers that the backbone route count dropped and confirm no subnet became unreachable.
- The IPv6 side is dark: OSPFv3: A two-area network works on IPv4 but its IPv6 subnets are unreachable; set up OSPFv3 with the same area layout, find the missing interfaces and prove it by pinging every IPv6 subnet.
- Announce a static route to everyone: Redistribute a router’s static lab-network route into OSPF and show it appearing as type E2 on the other routers.
- An external route vanishes in an NSSA: Read the LSA types to find why a connected network in an NSSA never reaches the backbone, fix it and show the Type 7 being translated to Type 5 in the database.
- Two exits, one loop: Find the loop caused by both of Piril Bakery’s internet exits originating an unconditional default route, make the default announced only while the exit is up, and test it by shutting one link.
- No hellos towards the user LAN: Stop OSPF hellos towards the user LAN with a passive interface, and show with tcpdump that no hellos leave while the network is still advertised.
- Keep the rogue lab router out: Show an unauthorised router added to your own lab network injecting routes, turn on authentication on the backbone and prove the rogue device can no longer become a neighbour.
- Cut a 40-second outage below one second: Build a test measuring how long the path takes to change when a link drops, enable BFD and compare the outage time before and after with measurements.
About this course
You run OSPF on several routers with FRRouting, manage areas, costs and convergence, and watch the network heal itself when a link breaks.
What you will learn
- OSPF basics
- Multi-area OSPF
- Operations and security
- Wrap-up
Prerequisites
You should be comfortable with the level 101 and 201 topics of the same path.
Lab environment
Lessons run in your own Kali Linux terminal in the browser, connected to a private lab network. Nothing to install.
Frequently asked questions
- Is this course right for my level?
- The course is at level 301; it assumes you know the topics of the lower-level courses.
- Is there anything to install?
- No. Every lesson runs in your own lab environment that opens in the browser.
- How do lessons work?
- Each lesson has 8 to 10 steps and a short quiz. Early steps show the command to type, later steps give less help; if two attempts fail, the solution opens.
- Can I try it for free?
- Yes. The first three lessons of every course are free.