Routing Protocols
EIGRP protocol
Objectives
Describe the background and history of Enhanced
Interior Gateway Routing Protocol (EIGRP).
Examine the basic EIGRP configuration commands
and identify their purposes.
Calculate the composite metric used by EIGRP.
Describe the concepts and operation of DUAL.
Describe the uses of additional configuration
commands in EIGRP.
Introduction
Reliable Transport Protocol (RTP)
Purpose of RTP
–Used by EIGRP to transmit and receive
EIGRP packets
Characteristics of RTP
–Involves both reliable & unreliable delivery of
EIGRP packet
Reliable delivery requires
acknowledgment from destination
Unreliable delivery does not require an
acknowledgement from destination
–Packets can be sent
Unicast
Multicast
–Using address 224.0.0.10
EIGRP’s 5 Packet Types
Hello packets
–Used to discover & form adjacencies with neighbors
Update packets
–Used to propagate ينقل
routing information
Acknowledgement
packets
–Used to acknowledge تس
receipt of update, query &
reply packets
Query & Reply packets
Used by DUAL (diffusing
update algorithm ) for
searching of networks
Query packets
-Can use
Unicast
Multicast
Reply packet
-Use only
unicast
Purpose of Hello Protocol
–To discover & establish adjacencies with neighbor routers
Characteristics of hello protocol
–Time interval for sending hello packet
Most networks it is every 5 seconds
Multipoint non broadcast multi-access networks
–Unicast every 60 seconds
-Holdtime
This is the maximum time
router should wait before
declaring a neighbor down
Default holdtime
–3 times hello interval
EIGRP Bounded Updates
EIGRP only sends update when there is a change in
route status
Partial update
–A partial update includes only the route information that has
changed – the whole routing table is NOT sent
Bounded update
–When a route changes, only those devices that are impacted
will be notified of the change
EIGRP’s use of partial bounded updates minimizes use
of bandwidth
Diffusing Update Algorithm (DUAL)
–Purpose
•EIGRP’s primary method for preventing routing loops
–Advantage of using DUAL
•Provides fast convergence time by keeping a list of loopfree
backup routes.
Administrative Distance (AD)
–Defined as the trustworthiness of the source route
EIGRP default administrative distances
–Summary routes = 5
–Internal routes = 90
–External routes = 170
Authentication
EIGRP can
– Encrypt routing information
– Authenticate routing information
