Configuration Guide: EIGRP Stub Routing

From: IP Routing: EIGRP Configuration Guide, Cisco IOS Release 15 M&T

• Bandwidth and memory can be conserved by summarizing and filtering routes in the distribution device. 
• The remote device need not receive routes that have been learned from other networks because the remote device must send all non-local traffic, regardless of the destination, to the distribution device. If a true stub network is desired, the distribution device should be configured to send only a default route to the remote device. 
• The EIGRP stub routing feature does not automatically enable summarization on distribution devices.
• The remote device can be dual-homed to two or more distribution devices.
• To ensure that traffic from distribution devices are not routed through a remote device, you can configure route summarization on the distribution device and the remote device.
• It is typically undesirable for traffic from a distribution device to use a remote device as a transit path.
• The EIGRP stub routing feature can prevent this problem by preventing the remote device from advertising core routes back to the distribution devices.
• The EIGRP stub routing feature should be used only on stub devices. A stub device is defined as a device connected to the network core or distribution layer through which core transit traffic should not flow. A stub device should not have any EIGRP neighbors other than distribution devices. Ignoring this restriction will cause undesirable behavior.

Configuring the EIGRP Stub Routing Autonomous System Configuration

Device(config)# router eigrp 1
! Configures a remote device as an EIGRP stub device.
! Command syntax: eigrp stub [receive-only] [leak-map name] [connected] [static] [summary] [redistributed] 
Device(config-router)# eigrp stub connected static

! Verifies that a remote device has been configured as a stub device with EIGRP. Enter this command on the distribution device. The last line of the output displays the stub status of the remote or spoke device.
Device# show ip eigrp neighbors detail

! The eigrp stub command is used to configure the device as a stub that advertises connected and summary routes:
Device(config)# router eigrp 1
Device(config-router)# network 10.0.0.0
Device(config-router)# eigrp stub

! The eigrp stub command is used with the connected and static keywords to configure the device as a stub that advertises connected and static routes (sending summary routes will not be permitted):
Device(config)# router eigrp 1
Device(config-router)# network 10.0.0.0
Device(config-router)# eigrp stub connected static

! The eigrp stub command is issued with the leak-map name keyword-argument pair to configure the device to reference a leak map that identifies routes that would have been suppressed:
Device(config)# router eigrp 1
Device(config-router)# network 10.0.0.0
Device(config-router)# eigrp stub leak-map MAP1

! The eigrp stub command is issued with the receive-only keyword to configure the device as a receive-only neighbor (connected, summary, and static routes will not be sent):
Device(config)# router eigrp 1
Device(config-router)# network 10.0.0.0
Device(config-router)# eigrp stub receive-only

! The eigrp stub command is issued with the redistributed keyword to configure the device to advertise other protocols and autonomous systems:
Device(config)# router eigrp 1
Device(config-router)# network 10.0.0.0
Device(config-router)# eigrp stub redistributed

Configuring the EIGRP Stub Routing Named Configuration

Device(config)# router eigrp WOOBAR
Device(config-router)# address-family ipv4 autonomous-system 45000
! Configures a device as a stub using EIGRP.
Device(config-router-af) eigrp stub leak-map MAP1

! Displays neighbors discovered by EIGRP.
Device# show eigrp address-family ipv4 neighbors detail