Cisco 10000 - Manual (Page 237)

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Cisco 10000 Series Router Software Configuration Guide
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Chapter 7 Configuring IP Unnumbered on IEEE 802.1Q VLANs
Restrictions for IP Unnumbered on VLANs
Restrictions for IP Unnumbered on VLANs
The IP Unnumbered on VLANs feature has the following restrictions:
• You can configure IP unnumbered on only Ethernet VLAN subinterfaces and point-to-point
interfaces.
• If you configure more than 14,000 IP unnumbered subinterfaces and you have configured EIGRP on
all interfaces on a router, the router can stop responding. To avoid this problem, use the
passive-interface default command (which disables all router interfaces from sending routing
updates) and then configure the no passive-interface command on selected interfaces you want to
send routing updates.
Configuration Tasks for IP Unnumbered on VLANs
To configure the IP Unnumbered on VLANs feature, perform at least one of the following configuration
tasks:
• Configuring IP Unnumbered for an Ethernet VLAN Subinterface, page 7-3
• Configuring IP Unnumbered for a Range of Ethernet VLAN Subinterfaces, page 7-4
Configuring IP Unnumbered for an Ethernet VLAN Subinterface
To configure IP unnumbered for an Ethernet VLAN subinterface, enter the following commands
beginning in global configuration mode:
Command Purpose
Step 1 Router(config)# interface type number
slot/module/port.subinterface
Configures a subinterface and enters subinterface configuration
mode.
Step 2 Router(config-subif)# encapsulation dot1q
vlan-id [native]
Enables IEEE 802.1Q encapsulation of traffic on a specified
subinterface in a virtual LAN (VLAN). IEEE 802.1 Q
enscapsulation is disabled by default.
The vlan-id argument is the virtual LAN identifier. Valid values
are from 1 to 4095.
The native option sets the VLAN ID value of the port to the value
you specify in the vlan-id argument.
Step 3 Router(config-subif)# ip unnumbered type
number
Enables IP processing on a serial interface without assigning an
explicit IP address to the interface. IP unnumbered is disabled by
default.
The type and number arguments indicate the type and number of
another interface on which the router has an assigned IP address.
It cannot be another unnumbered interface.