Chapter 7: EIGRP
Instructor Materials
CCNP Enterprise: Core Networking
,Chapter 7 Content
This chapter covers the following content:
• EIGRP Fundamentals - This section explains how EIGRP establishes a
neighbor adjacency with other routers and how routes are exchanged
with other routers.
• Path Metric Calculation - This section explains how EIGRP calculates
the path metric to identify the best and alternate loop-free paths.
• Failure Detection and Timers - This section explains how EIGRP
detects the absence of a neighbor and the convergence process.
• Route Summarization - This section explains the logic and
configuration related to summarizing routes on a router.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2
,EIGRP Fundamentals
• EIGRP overcomes the deficiencies of other distance vector routing protocols with
unequal-cost load balancing, support for networks 255 hops away, and rapid
convergence features.
• EIGRP uses a diffusing update algorithm (DUAL) to identify network paths and enable
fast convergence using precalculated loop-free backup paths.
• EIGRP adds to the route selection algorithm logic that uses factors outside hop count.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3
, EIGRP Fundamentals
Autonomous Systems
A router can run multiple EIGRP processes. Each process operates under the context of
an autonomous system, which represents a common routing domain. Routers within the
same domain use the same metric calculation formula and exchange routes only with
members of the same autonomous system, as shown in the figure.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4
Instructor Materials
CCNP Enterprise: Core Networking
,Chapter 7 Content
This chapter covers the following content:
• EIGRP Fundamentals - This section explains how EIGRP establishes a
neighbor adjacency with other routers and how routes are exchanged
with other routers.
• Path Metric Calculation - This section explains how EIGRP calculates
the path metric to identify the best and alternate loop-free paths.
• Failure Detection and Timers - This section explains how EIGRP
detects the absence of a neighbor and the convergence process.
• Route Summarization - This section explains the logic and
configuration related to summarizing routes on a router.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 2
,EIGRP Fundamentals
• EIGRP overcomes the deficiencies of other distance vector routing protocols with
unequal-cost load balancing, support for networks 255 hops away, and rapid
convergence features.
• EIGRP uses a diffusing update algorithm (DUAL) to identify network paths and enable
fast convergence using precalculated loop-free backup paths.
• EIGRP adds to the route selection algorithm logic that uses factors outside hop count.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 3
, EIGRP Fundamentals
Autonomous Systems
A router can run multiple EIGRP processes. Each process operates under the context of
an autonomous system, which represents a common routing domain. Routers within the
same domain use the same metric calculation formula and exchange routes only with
members of the same autonomous system, as shown in the figure.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 4
