Configuring Summary Aggregate Addresses; Disabling Eigrp Split Horizon - Cisco 7604 Configuration Manual

Configuring EIGRP
To disable automatic router summarization, enter the following command in router configuration mode
for the EIGRP routing process:
hostname(config-router)# no auto-summary
Automatic summary addresses have an adminstrative distance of 5. You cannot configure this value.
Note

Configuring Summary Aggregate Addresses

You can configure a summary addresses on a per-interface basis. You need to manually define summary
addresses if you want to create summary addresses that do not occur at a network number boundary or
if you want to use summary addresses on a FWSM with automatic route summarization disabled. If any
more specific routes are in the routing table, EIGRP will advertise the summary address out the interface
with a metric equal to the minimum of all more specific routes.
To create a summary address, perform the following steps:
Enter interface configuration mode for the interface on which you are creating a summary address by
Step 1
entering the following command:
hostname(config)# interface phy_if
Create the summary address by entering the following command:
Step 2
hostname(config-if)# summary-address eigrp as-num address mask [distance]
By default, EIGRP summary addresses that you define have an administrative distance of 5. You can
change this value by specifying the optional distance argument in the summary-address command.

Disabling EIGRP Split Horizon

Split horizon controls the sending of EIGRP update and query packets. When split horizon is enabled on
an interface, update and query packets are not sent for destinations for which this interface is the next
hop. Controlling update and query packets in this manner reduces the possibility of routing loops.
By default, split horizon is enabled on all interfaces.
Split horizon blocks route information from being advertised by a router out of any interface from which
that information originated. This behavior usually optimizes communications among multiple routing
devices, particularly when links are broken. However, with nonbroadcast networks, there may be
situations where this behavior is not desired. For these situations, including networks in which you have
EIGRP configured, you may want to disable split horizon.
If you disable split horizon on an interface, you must disable it for all routers and access servers on that
interface.
To disable EIGRP split-horizon, perform the following steps:
Enter interface configuration mode for the interface on which you are disabling split horizon by entering
Step 1
the following command:
hostname(config)# interface phy_if
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
8-28
Chapter 8 Configuring IP Routing and DHCP Services
OL-20748-01