Routing protocols are used to dynamically learn advertised routes from nearby routers. Imagine having to enter every possible route onto each router – nightmare.
Key information about some routing protocols covered by the ICND2:
EIGRP (Enhanced Interior Gateway Routing Protocol)
- Distance-vector protocol
- Classless
- Autonomous system – must be in the same autonomous system
- Cisco proprietary
- Administrative distance 90
- Shows as ‘D’ in the routing table
- Only routing protocol to use backup routes
- Supports IPv6 routed protocols
- Feasible successor – backup route – stored in topology table
- Successor – best route to a network – store in routing table
- Uses bandwidth and delay to determine best path
- Uses subnet mask
- multicast 224.0.0.10
- Dual algorithm
- Maintains three tables neighbor, topology and routing table.
OSPF (Open Shortest Path First)
- Link-state routing protocol
- Open standard protocol from IETF this makes OSPF more popular
- Administrative distance 110
- Shows as ‘O’ in the routing table
- Unlimited hop count
- Path metric – bandwidth
- Supports IPv6 routed protocols
- Converges quickly, not as quick as EIGRP
- Router ID is determined by highest IP first either by loopback or active interfaces
- multicast 224.0.0.5
- Uses wild card (inverse mask)
- SPF algorithm
- All areas must be connected to area 0
- Hello packets sent on the configured interface once every 10 seconds on broadcast and 30 seconds on NBMA (non-broadcast multi-access) networks such as frame-relay