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64 Cards in this Set
- Front
- Back
EIGRP was initially released in |
1992 as a proprietary protocol. |
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EIGRP includes features of both |
link-state and distance vector routing protocols. |
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EIGRP is still based on the key |
distance vector routing protocol principle. |
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The key distance vector routing protocol principle |
information about the rest of the network is learned from directly connected neighbors. |
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Diffusing Update Algorithm (DUAL) |
DUAL guarantees loop-free and backup paths throughout the routing domain. |
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Using DUAL, EIGRP stores all available backup routes for destinations so that it can |
quickly adapt to alternate routes when necessary. |
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Partial Updates |
the update only includes information about the route changes. |
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Bounded Updates |
the propagation of partial updates that are sent only to those routers that the changes affect. |
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EIGRP Supports: |
equal cost load balancing unequal cost load balancing |
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EIGRP has the capability for routing several different protocols using |
protocol-dependent modules (PDMs). |
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PDMs are responsible for 1: |
Maintaining the neighbor and topology tables. |
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PDMs are responsible for 2: |
Building and translating protocol-specific packets for DUAL |
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PDMs are responsible for 3: |
Interfacing DUAL to the protocol-specific routing table |
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PDMs are responsible for 4: |
Computing the metric and passing this information to DUAL |
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PDMs are responsible for 5: |
Implementing filtering and access lists |
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PDMs are responsible for 6: |
Performing redistribution functions to and from other routing protocols |
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PDMs are responsible for 7: |
Redistributing routes that are learned by other routing protocols |
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When a router discovers a new neighbor, it records the neighbor’s |
address and interface as an entry in the neighbor table. |
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EIGRP also maintains a topology table. The topology table contains all destinations that are |
advertised by neighboring routers. |
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There is also a separate topology table for each |
PDM. |
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The Reliable Transport Protocol (RTP) is unique to EIGRP and provides delivery of |
EIGRP packets to neighbors. |
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RTP includes both: |
reliable delivery unreliable delivery |
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Reliable RTP requires an |
acknowledgment. |
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An unreliable RTP packet does not require an |
acknowledgment. |
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RTP can send EIGRP packets as |
as unicast or multicast. |
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Multicast EIGRP packets for IPv4 use the reserved IPv4 multicast address |
224.0.0.10. |
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Multicast EIGRP packets for IPv6 are sent to the reserved IPv6 multicast sent to the reserved IPv6 multicast address |
FF02::A. |
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Authentication does not encrypt theEIGRP |
routing updates. |
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EIGRP Packet Types: |
Hello packets Update packets Acknowledgment packets Query packets Reply packets |
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Hello packets |
Used for neighbor discovery maintain neighbor adjacencies sent as multicast packets every five seconds. Unreliable, multicast. |
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Update packets |
Propagates routing information sent as a multicast or unicast Reliable, multi/unicast |
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Acknowledgment packets |
acknowledge the receipt of an EIGRP message. Unreliable, unicast. |
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Query packets |
Used to query routes from neighbors. Reliable, multi/unicast. |
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Reply packets |
Sent in response to an EIGRP query. Reliable, unicast. |
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EIGRP uses a Hold timer to determine the maximum time the router should wait to |
receive the next Hello before declaring that neighbor as unreachable. |
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By default, the hold time is three times the Hello interval, |
or 15 seconds. |
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If the hold time expires, EIGRP declares the route as |
down. |
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The autonomous system number used for EIGRP configuration is only significant to the |
EIGRP routing domain |
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The autonomous system number functions as a process ID to help routers keep track of multiple, running |
instances of EIGRP. |
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The EIGRP router ID is used to uniquely identify each router in the |
the EIGRP routing domain. |
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Determining the router-ID: |
Router-id > loopback > Highest IPv4 address |
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The use of Passive-interfaces: |
To suppress unnecessary update traffic To increase security controls |
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Show ip eigrp neighbors: H |
Lists the neighbors in the order that they were learned. |
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Show ip eigrp neighbors: Address |
IPv4 address of the neighbor. |
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Show ip eigrp neighbors: Interface |
Local interface on which this Hello packet was received. |
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Show ip eigrp neighbors: Hold |
Current hold time. |
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Show ip eigrp neighbors: Uptime |
Amount of time since this neighbor was added to the neighbor table. |
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Routing Update Sequence: |
R1: Hello R2: Update R2: Hello R1: Ack R1: Update R2: Ack |
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The metric calculation method (k values) and the EIGRP autonomous system number must match between EIGRP |
neighbors. |
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EIGRP uses the bandwidth and delay as a metric to calculate the |
preferred path to a network. |
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Most serial interfaces use the default bandwidth value of |
1544 kb/s. |
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Modifying the bandwidth value does not change the |
actual bandwidth of the link. |
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The bandwidth command only modifies the |
bandwidth metric. |
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delay is the cumulative (sum) of all interface delays |
along the path. |
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The decision process for all route computations is done by the |
DUAL Finite State Machine (FSM). |
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The DUAL FSM: |
tracks all routes uses EIGRP metrics to select efficient. loop-free paths. identifies the routes with the least-cost path to be inserted into the routing table. |
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A successor is a neighboring router that is used for |
packet forwarding |
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A successor is a neighboring router that is the |
least-cost route to the destination network. |
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The IP address of a successor is shown in a routing table entry right after the word |
via. |
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FD is the lowest calculated metric to reach the |
destination network. |
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DUAL backup paths are known as |
Feasible Successors (FSs). |
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A FS is a neighbor that has a loop-free backup path to the same network as the successor, and it satisfies the |
Feasibility Condition. |
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The FC is met when a neighbor’s Reported Distance (RD) to a network is |
less than the local router’s feasible distance. |
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If there are not any FSs in the topology table, DUAL puts the network into the |
active state. |