EIGRP – unequal cost load balancing, support for networks 255 hhops away, rapid convergence
DUAL – diffusing update algorithm to identify paths
Router can run multiple EIGRP processes separated by AS number. Autonomous System
PDM – protocol dependent modules to support multiple network protocols
EIGRP KEY TERMS
– successor route – route w/lowest path metric
– successor – first next hop router for successor route
– feasible distance – metric value for lowest metric path to reach destination
– reported distance – distance reported by router ot reach prefix
– feasibility condition – for route to be considered a backup route
– feasibility successor – a route that satisfies feasibility condition maintained as backup route
Topology Table
– network prefix
– EIGRP neighbors that advertise prefix
– metrics from each neighbor
– values used for calculating metric
EIGRP Packet Types
– Hello
– Request
– Update
– Query
– Reply
RTP – reliable transport protocol ensure packets are delivered
EIGRP forms neighbors
– Requires neighbor relationship before routes are processed and added to RIB
Matches Required for Neighborship
– metric formula K values
– primary subnet
– AS number match
– authentication
2 Methods Classic and Named
Classic – most config in process, some under interface
Named – hierarchy – address family, interface, topology,
passive interface – enabled w/routing protocol to advertise its interface into RIB but does not establish neighborship with other routers associated w/interface
authentication – authenticated routers become eigrp neighbors encrypt with md5 authentication w/keychain key # and password
wide metric – advertising and identifying interface speeds and delay accounts for higher metrics
load balancing – allows multiple successors to be installed into rib
unequal cost load balancing must change variance multiplier
variance value – fd for a route multiplied by eigrp variance multiplier
failure detection
– default timers 5 sec, 60 on slow
– hold timers 15 sec, 180 on slow
stuck in active
– if router receives no response within 90 sec
summerization – reducing routing table by advertising less specific network prefix than multiple more specific network prefixes
summary discard routes – routing loop prevention
summerization metrics – lowest metric of component routes
stub router – advertise all other neighbors isolated should not be queried when routes go active
stub site router – advertises to all other upstream neighbors that are isolated
eigrp max available bandwidth 50% and 50% for data
split horizon – prevents advertisements of reverse routes enabled by default
offset list – modify metric value of route
Neighborship Might Not Form If…
– int down
– mismatched as numbers
– incorrect network statement
– mismatched K value
– passive interface
– different subnets
– authentication
– ACL
– Timers
ACL may be denying EIGRP multicast address 224.0.0.10
EIGRPv6
FF02::A mutlicast link local
classic and named
router id
on interface
no concept of classless/classfull
default route ::/0
