Ch. 7 - EIGRP Flashcards
EIGRP is considered what type of routing protocol? What makes it unique compared to other routing protocols?
IGRP (Internal Gateway RP), but also a distance-vector routing protocol. It combines some advantages of link-state routing protocols but is still based on the principle of distance-vector routing.
What are some of the important features of EIGRP?
1) Rapid convergence
2) Load balancing (ECMP and unequal-cost MP)
3) Loop-free, classless routing (supports VLSM)
4) Multi-address family support (IPv4 and IPv6)
5) Reduced bandwidth use from the way it updates routes
What multicast addresses does EIGRP use?
IPv4 - 224.0.0.10
IPv6 - FF00::A
What is an EIGRP successor route? How about a feasible successor route?
Successor route - lowest metric path to a destination, considered primary route to a network and installed in RIB
Feasible successor - backup route to a destination, likely the SECOND-lowest path to a network
What parameters must match to establish an EIGRP adjacency?
1) AS number
2) K values (for metric calculation)
3) Common subnet (EIGRP uses an interface’s primary address)
4) Authentication method and password
What command would you use to stop an interface from sending and processing EIGRP hello packets?
passive-interface
What command would you use to stop an interface from sending and processing EIGRP hello packets?
passive-interface
What characteristics does EIGRP use for its metric calculation?
1) Bandwidth
2) Load
3) Delay
4) Reliability
What problem does EIGRP wide metrics solve?
Normal EIGRP metrics does not scale correctly for high-bandwidth interfaces. Interfaces that are GigEthernet and higher appear as a GigEthernet interface.
Wide metrics supports interfaces up to ~4.2Tbps
In EIGRP, what is the difference between a route’s reported distance (RD) and its feasible distance (FD)?
Reported distance - EIGRP metric for a neighbor to get to a destination
Feasible distance - EIGRP metric for the local router to get to a destination. In other words, this is the reported distance + metric from local router to neighbor
What are the different administrative distances (ADs) for EIGRP?
Internal routes - 90
External routes - 170
Summary routes - 5
In EIGRP, what would you use to enable (or disable) ECMP?
Use the “maximum-paths” command
Set this to “1” to disable ECMP
If ECMP is configured but only one route is used, what could be the problem?
The paths to the destination may not have the same metric. ECMP implies that the routes should have an equal cost
What command would you use to install routes in the RIB that have an un-equal cost to the current best cost?
“variance” command
Setting this to “1” disables un-equal cost load balancing
What EIGRP mode supports IPv6?
“Named” mode
