EIGRP Flashcards
What type of routing protocol is EIGRP?
Enhanced Distance Vector Protocol
What metric does EIGRP use for its calculations?
Bandwidth and Delay
What load balancing feature does EIGRP allow that other protocols don’t?
Unequal-cost load balancing
What algorithm does it to use to select best paths?
Diffusing Update Algorithm (DUAL)
What is reported distance?
Also referred to as Administrative Distance, it is the cost between the next-hop and the destination
What is feasible distance?
This the cost between our local router and the next-hop plus the next-hop’s RD to the destination
What is a successor?
This is the neighboring router that has the best-path to the destination that is guaranteed to not be in a routing loop (lowest FD)
What is a successor route?
This is the best route that goes into the routing table
What is the feasibility condition?
This is the condition that the reported distance of the feasible successor must be lower than the feasible distance of the current successor to be considered a feasible successor
What does RD lower than FD confirm?
This confirms that there is no loop in the topology because the route must have a RD less than the current FD of the current successor route
What happens if our current successor route goes down, and we have a feasible successor?
This feasible successor route replaces the current successor route in the routing table
When are feasible successors selected?
They are selected at the same time as the successor route, but are kept in the topology table (not routing table) as backups
What is included in the EIGRP table?
Neighbor Tables, Topology Table and the Routing Table
What is in the neighbor table?
Contains EIGRP neighbor addresses
What is in the Topology table?
Contains all destinations advertised by neighboring routers
What is in the routing table?
Contains EIGRP successor routes. EIGRP routes are denoted by the letter D. The next hop address, and the time since last update packet received, and the local router exit interface to destination
What is a passive route?
A route that isn’t being recalculated and is in the ‘passive’ table state
What is an active route?
This is a route that is undergoing re-computation. This means we lost our best-path to a destination and we are finding an alternative
What underlying protocol does EIGRP use for reliable transmission?
Reliable Transport Protocol (RTP)
Why is RTP used instead of TCP/IP?
EIGRP does not use TCP/IP because IPX and Appletalk were in use when EIGRP was created
What packets are not acknowledged in EIGRP?
Hello and ACK packets
What do the numbers (90/40514506) mean in the EIGRP routing table?
First number is the administrative distance (AD) and the second number is the feasible distance (FD) (metric)
What is a metric?
A value that is assigned to a particular route/interface/etc. that is used to determine the cost of it.
What are the 5 EIGRP packets?
Hello, Request, Update, Query, Reply
What is the EIGRP Hello packet used for?
Used for discovery of EIGRP neighbors
What is the EIGRP Request packet used for?
Used to request specific information
What is the EIGRP Update packet used for?
Used to transmit routing information
What is the EIGRP Query packet used for?
Sent out to search for another path to a destination during convergence
What is the EIGRP Reply packet used for?
Sent in response to a query packet