Cisco ICND2 – Compare and contrast methods of routing and routing protocols

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
  • 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
  • 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