EIGRP design principles
- EIGRP works for arbitrary topologies for small to medium networks.
- A flat EIGRP network doesn’t really scale beyond 400 routers and will lead to performance issuse
- How to solve this?
- Stub areas, summerization, route filtering limits the query scope
- If EIGRP doesn’t have a feasible successor it will query all it’s neighbours.
- “I don’t have a route anymore, don’t route through me, give me a viable route”.
- BFD to optimize convergence (100ms wtih 1000 routes).
- 2 second hello timer, 6 second hold timer ( recommended )
Multiple EIGRP design principles
- Used to merge two networks ( Acquisitions )
- Different administrative groups in a company
- a way to devide large networks ( and control queries )
- Routes are distributed between AS ( don’t loop! )
OSPF design principles
- Number of neighbouring routers ( no more than 60 ).
- Number of routers in an area ( no more than 50 ).
- Number of areas connected to a router ( no more than 3 ).
- LSDB has to be maintained for all area’s
- The router acting as the DR ( best router).
- Ammount of data in an area impatcs OPSF performance
- Stub / Total stub
- Areas should be designed around geography and functional boundries
- Summarization minimizes route change (flapping) impact
- Large networks only have ARBS in AREA 0
- Contigious splitable adressing
BGP design principles
- BGP as IGP:
- Vendor interoperability
- per-hop traffic engineering,
- unequal-cost loadbalancing / anycast routing
- simpler troubleshouting (as-path)
- reduced flooding
- Trust border controll
- Default timers are very slow
- Not available on low-end routers (layer 3 switches)
- Not as dynamic
- Full mesh requirement
- Route Reflector design
- Confederate design
All Routing protocols
All routing protocols must detect, propagate, process and update.