Chapter 4 Configuring Layer 3 Interface; Routed Interfaces; Subinterfaces - Cisco 7604-RSP720C-R Configuration Manual

Information About Layer 3 Interfaces
S e n d d o c u m e n t c o m m e n t s t o n e x u s 7 k - d o c f e e d b a c k @ c i s c o . c o m
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Routed Interfaces

You can configure a port as a Layer 2 interface or a Layer 3 interface. A routed interface is a physical
port that can route IP traffic to another device. A routed interface is a Layer 3 interface only and does
not support Layer 2 protocols, such as the Spanning Tree Protocol (STP).
All Ethernet ports are routed interfaces by default. You can change this default behavior with the CLI
setup script or through the system default switchport command.
You can assign an IP address to the port, enable routing, and assign routing protocol characteristics to
this routed interface.
Beginning with Cisco Release 4.2(1), you can assign a static MAC address to a Layer 3 interface. By
default, the MAC address for the Layer 3 interfaces is the MAC address of the VDC it is assigned to.
For information on configuring MAC addresses, see the Cisco Nexus 7000 Series NX-OS Layer 2
Switching Configuration Guide, Release 5.x.
You can also create a Layer 3 port channel from routed interfaces. For more information on port
channels, see
Routed interfaces and subinterfaces support exponentially decayed rate counters. Cisco NX-OS tracks
the following statistics with these averaging counters:
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Subinterfaces

You can create virtual subinterfaces on a parent interface configured as a Layer 3 interface. A parent
interface can be a physical port or a port channel.
Subinterfaces divide the parent interface into two or more virtual interfaces on which you can assign
unique Layer 3 parameters such as IP addresses and dynamic routing protocols. The IP address for each
subinterface should be in a different subnet from any other subinterface on the parent interface.
You create a subinterface with a name that consists of the parent interface name (for example, Ethernet
2/1) followed by a period and then by a number that is unique for that subinterface. For example, you
could create a subinterface for Ethernet interface 2/1 named Ethernet 2/1.1 where .1 indicates the
subinterface.
Cisco NX-OS enables subinterfaces when the parent interface is enabled. You can shut down a
subinterface independent of shutting down the parent interface. If you shut down the parent interface,
Cisco NX-OS shuts down all associated subinterfaces as well.
One use of subinterfaces is to provide unique Layer 3 interfaces to each virtual local area network
(VLAN) supported by the parent interface. In this scenario, the parent interface connects to a Layer 2
trunking port on another device. You configure a subinterface and associate the subinterface to a VLAN
ID using 802.1Q trunking.
Cisco Nexus 7000 Series NX-OS Interfaces Configuration Guide, Release 5.x
4-2
Tunnel Interfaces, page 4-4
High Availability, page 4-4
Virtualization Support, page 4-5
Chapter 6, "Configuring Port Channels."
Input packets/sec
Output packets/sec
Input bytes/sec
Output bytes/sec
Chapter 4 Configuring Layer 3 Interfaces
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