EIGRP Flashcards
What is EIGRP?
Cisco proprietary distance-vector routing protocol
Features of EIGRP
Diffusing Update Algorithm (DUAL)
Establishing Neighbor Adjacencies
Reliable Transport Protocol
Equal and unequal cost load balancing
Protocol used by EIGRP
Protocol-dependent modules (PDMs)
Security in EIGRP
Supports authentication but does not encrypt the EIGRP routing updates
EIGRP packet types
Hello , Update, Acknowledgement, Query, Reply
EIGRP broadcast
Uses multicast and unicast
IPv4 - 224.0.0.10
IPv6 - FF02::A
A packet type that is sent to initially exchange topology information or topology change. Contains needed routing information
Update Packets
Requires acknowledgement
A “dateless” Hello packets used to indicate receipt of any EIGRP packet during a “reliable”
Acknowledgement Packet
What packets require acknowledgement ?
update, query and reply packets
2 Packets that used DUAL when searching for networks
Query and reply
How to identify EIGRP
Autonomous System
Passive Interface Command
Prevents neighbor relationships from being established
Routing updates from a neighbor are ignored
EIGRP metrics
Bandwidth - Lowest
Delay - Cumulative
Reliability - Worsts
Load - Worsts
Command used to Examine the values for EIGRP Metrics
show interfaces
Purpose of Diffusing Update Algorithm (DUAL)
Provide the best and backup loop-free paths
Neighboring router that is used for packet forwarding and is the least-cost route to the destination network
Successor
Actual metric of a route from the current router. Lowest calculated metric to reach the destination network
Feasible Distance
listed in the routing table as the second number inside the brackets
Are “Backup Paths” that are loop-free. Must comply to a feasibility condition
Feasible successor (FS)
Called “advertised distance” the reported metric from the neighbor advertising the route
Reported Distance (RD) if RD
command to list all
successors and FSs to destination networks.
show ip eigrp topology
Similarities is EIGRPv2 & v3
Same protocol number (88)
Maintains a topology table and queries if no FS are avail
Uses DUAL to calculate the successor routes
Administrative Distance of internal, summary and external
90,5,170
Which bandwidth value is used when calculating the EIGRP metric of a route?
the slowest bandwidth of all outgoing interfaces between the source and destination
What two conditions will result in an EIGRP route going into the active state
The successor is down
There is no feasible successor.
