38-38
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-12247-04
Chapter 38 Configuring IP Unicast Routing
Configuring EIGRP
need not be acknowledged. Other types of packets (such as updates) require acknowledgment, which
is shown in the packet. The reliable transport has a provision to send multicast packets quickly when
there are unacknowledged packets pending. Doing so helps ensure that convergence time remains
low in the presence of varying speed links.
•
The DUAL finite state machine
embodies the decision process for all route computations. It tracks
all routes advertised by all neighbors. DUAL uses the distance information (known as a metric) to
select efficient, loop-free paths. DUAL selects routes to be inserted into a routing table based on
feasible successors. A successor is a neighboring router used for packet forwarding that has a
least-cost path to a destination that is guaranteed not to be part of a routing loop. When there are no
feasible successors, but there are neighbors advertising the destination, a recomputation occurs. This
is the process whereby a new successor is determined. The amount of time it takes to recompute the
route affects the convergence time. Recomputation is processor-intensive; it is advantageous to
avoid recomputation if it is not necessary. When a topology change occurs, DUAL tests for feasible
successors. If there are feasible successors, it uses any it finds to avoid unnecessary recomputation.
•
The
protocol-dependent modules
are responsible for network layer protocol-specific tasks. An
example is the IP EIGRP module, which is responsible for sending and receiving EIGRP packets
that are encapsulated in IP. It is also responsible for parsing EIGRP packets and informing DUAL
of the new information received. EIGRP uses DUAL for routing decisions, but the results are stored
in the IP routing table. EIGRP is also responsible for redistributing routes learned by other IP
routing protocols.
These sections contain this configuration information:
•
Default EIGRP Configuration, page 38-38
•
Configuring Basic EIGRP Parameters, page 38-41
•
Configuring EIGRP Interfaces, page 38-42
•
Configuring EIGRP Route Authentication, page 38-42
•
EIGRP Stub Routing, page 38-43
•
Monitoring and Maintaining EIGRP, page 38-44
Note
To enable EIGRP, the switch or stack master must be running the IP services feature set.
Default EIGRP Configuration
shows the default EIGRP configuration.
Table 38-7
Default EIGRP Configuration
Feature
Default Setting
Auto summary
Enabled. Subprefixes are summarized to the classful network
boundary when crossing classful network boundaries.
Default-information
Exterior routes are accepted, and default information is passed
between EIGRP processes during redistribution.
