Routing protocols

Comparing OSPF and EIGRP

Parameter	OSPF	EIGRP
Type	Link State	Distance vector
Metric	Bandwidth	Bandwidth + delay

OSPF highlights

OSPF Highlights

Term	Explanation
Router-ID	Priority 1: Set with the router-id command
	Priority 2: Highest loopback IP address
	Priority 3: Highest active interface IP address
DR Designated Router	Priority 1: Highest priority. Set with the ip ospf priority command on the interface
	Priority 2: Higest Router-ID
BDR Backup Designated Router	Priority 1: Next highest priority. Set with the ip ospf priority command on the interface
	Priority 2: Next higest Router-ID
Communication	Uses multicast addresses 224.0.0.5 and 224.0.0.6
	224.0.0.5 - Multicast to neighbors
	224.0.0.6 - Multicast to DR and BDR. DR will relay the information to DROthers on 224.0.0.5
Metric	Uses bandwidth called cost - Default calculated as 108 / bandwidth
	Metric is the accumulated cost to the destination network
	default highest bandwidth is 108 = 100 Mbps. Change with the auto-cost reference-bandwidth command. Remember to change on all routers.
	Serial interfaces - Remember to set the bandwidth command on serial interfaces to reflect the actual clock rate. (1,544 Mbps or 128 Kbps default)
Neighbour establisment	Neighbors are established if hello- and dead-time interval are the same and network type are the same
hello interval	default 10 seconds on point-to-point and multi-access networks
	Default 30 seconds on non-broadcast multi-access (NBMA) segments (Frame Relay, X.25, ATM)
Dead-time interval	default 40 seconds on point-to-point and multi-access networks
	Default 120 seconds on non-broadcast multi-access (NBMA) segments (Frame Relay, X.25, ATM)
Packet types	Hello - Discovers neighbors and builds adjacencies with them
	LSR - Link State Request - Request information about specific link state information
	LSU - Link State Update - Send information about specifically requested link states
	LSAck - Links State Acknogledgement