Table Of Contents

Configuring IPv4

Information About IPv4

Multiple IPv4 Addresses

Virtualization Support

Licensing Requirements for IPv4

Prerequisites for IPv4

Guidelines and Limitations

Configuring IPv4

Configuring IPv4 Addressing

Configuring Multiple IP Addresses

Field Descriptions for IP

Additional References

Related Documents

Standards

Configuring IPv4

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This chapter describes how to configure Internet Protocol version 4 (IPv4) on the device.

This chapter includes the following sections:

•Information About IPv4

•Licensing Requirements for IPv4

•Prerequisites for IPv4

•Guidelines and Limitations

•Configuring IPv4

•Field Descriptions for IP

•Additional References

Information About IPv4

You can configure IP on the device to assign IP addresses to network interfaces. When you assign IP addresses, you enable the interfaces and allow communication with the hosts on those interfaces.

You can configure an IP address as primary or secondary on a device. An interface can have one primary IP address and multiple secondary addresses. All networking devices on an interface should share the same primary IP address because the packets that are generated by the device always use the primary IPv4 address. Each IPv4 packet is based on the information from a source or destination IP address. See the "Multiple IPv4 Addresses" section.

You can use a subnet to mask the IP addresses. A mask is used to determine what subnet an IP address belongs to. An IP address contains the network address and the host address. A mask identifies the bits that denote the network number in an IP address. When you use the mask to subnet a network, the mask is then referred to as a subnet mask. Subnet masks are 32-bit values that allow the recipient of IP packets to distinguish the network ID portion of the IP address from the host ID portion of the IP address.

The IP feature in the Cisco NX-OS system is responsible for handling IPv4 packets that terminate in the supervisor module, as well as forwarding of IPv4 packets, which includes IPv4 unicast/multicast route lookup, reverse path forwarding (RPF) checks, and software access control list/policy based routing (ACL/PBR) forwarding. The IP feature also manages the network interface IP address configuration, duplicate address checks, static routes, and packet send/receive interface for IP clients.

This section includes the following topics:

•Multiple IPv4 Addresses

•Virtualization Support

Multiple IPv4 Addresses

The Cisco NX-OS system supports multiple IP addresses per interface. You can specify an unlimited number of secondary addresses for a variety of situations. The most common are as follows:

•When there are not enough host IP addresses for a particular network interface. For example, if your subnetting allows up to 254 hosts per logical subnet, but on one physical subnet you must have 300 host addresses, then you can use secondary IP addresses on the routers or access servers to allow you to have two logical subnets using one physical subnet.

•Two subnets of a single network might otherwise be separated by another network. You can create a single network from subnets that are physically separated by another network by using a secondary address. In these instances, the first network is extended, or layered on top of the second network. A subnet cannot appear on more than one active interface of the router at a time.

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Note If any device on a network segment uses a secondary IPv4 address, all other devices on that same network interface must also use a secondary address from the same network or subnet. The inconsistent use of secondary addresses on a network segment can quickly cause routing loops.

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Figure 2-1 Reverse ARP

Virtualization Support

IPv4 supports Virtual Routing and Forwarding instances (VRFs). VRFs exist within virtual device contexts (VDCs). By default, Cisco NX-OS places you in the default VDC and default VRF unless you specifically configure another VDC and VRF. For more information, see the Cisco NX-OS Virtual Device Context Configuration Guide.

Licensing Requirements for IPv4

The following table shows the licensing requirements for this feature:

Product	License Requirement
DCNM	IP requires no license. Any feature not included in a license package is bundled with the Cisco DCNM and is provided at no charge to you. For a complete explanation of the DCNM licensing scheme, see the Cisco DCNM Licensing Guide.
NX-OS	IP requires no license. Any feature not included in a license package is bundled with the Cisco NX-OS system images and is provided at no extra charge to you. For a complete explanation of the NX-OS licensing scheme, see the Cisco NX-OS Licensing Guide.

Prerequisites for IPv4

IPv4 has the following prerequisites:

•Can only be configured on Layer 3 interfaces.

Guidelines and Limitations

IPv4 has the following guidelines and limitations and restrictions:

•You can configure a secondary IP address only after you configure the primary IP address.

Configuring IPv4

You can access IP addressing for Layer 3 interfaces from the Interfaces feature selection. Figure 2-2 shows the Layer 3 interfaces.

Figure 2-2 Configuring Layer 3 Interfaces

For more information about the Data Center Network Manager features, see the Cisco Data Center Network Manager Fundamentals Guide

This section includes the following topics:

•Configuring IPv4 Addressing

•Configuring Multiple IP Addresses

Configuring IPv4 Addressing

You can assign a primary IP address for a network interface.

DETAILED STEPS

To configure an IPv4 address on a routed interface, follow these steps:

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Step 1 From the Feature Selector pane, choose Interfaces > Physical > Ethernet.

The available devices appear in the Summary pane (see Figure 2-2).

Step 2 From the Summary pane, double-click the device to display a list of slots.

Step 3 Double-click the slot to display a list of interfaces.

Step 4 Click the interface that you want to configure as a routed interface.

The system highlights the interface in the Summary pane, and tabs appear in the Details pane.

Step 5 From the Details pane, click the Port Details tab.

The Port Details tab appears.

Step 6 From the Port Details tab, expand the Port Mode Settings section.

The port mode appears.

Step 7 From the Mode drop-down list, choose Routed.

The IP address information appears in the Details pane and Cisco NX-OS removes any Layer 2 configuration.

Step 8 (Optional) From the IPv4 Address Settings, set the Primary field to the IPv4 address for this routed interface.

Step 9 (Optional) Set the Net mask field to the network mask for this IPv4 address in dotted decimal notation.

Step 10 From the menu bar, choose File > Deploy to apply your changes to the device.

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Configuring Multiple IP Addresses

You can only add secondary IP addresses after you configure primary IP addresses.

DETAILED STEPS

To configure an IPv4 secondary address or helper address on a routed interface, follow these steps:

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Step 1 From the Feature Selector pane, choose Interfaces > Physical > Ethernet.

The available devices appear in the Summary pane (see Figure 2-2).

Step 2 From the Summary pane, double-click the device to display a list of slots.

Step 3 Double-click the slot to display a list of interfaces.

Step 4 Click the interface that you want to configure as a routed interface.

The system highlights the interface in the Summary pane, and tabs appear in the Details pane.

Step 5 From the Details pane, click the Port Details tab.

The Port Details tab appears.

Step 6 From the Port Details tab, expand the Port Mode Settings section.

The port mode appears.

Step 7 (Optional) From the IPv4 Address settings section, in the Secondary area, right-click and choose Add Secondary IP to add a secondary IP address.

Step 8 From the secondary area, in the IP address field, enter an IPv4 address.

Step 9 From the net mask field, enter the network mask for this IPv4 address in dotted decimal notation.

Step 10 (Optional) From the IPv4 Address settings section, in the Helper area, right-click and choose Add Helper IP to add a helper IP address.

Step 11 From the Helper area, in the IP address field, enter an IPv4 address.

Step 12 From the menu bar, choose File > Deploy to apply your changes to the device.

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Field Descriptions for IP

See the Basic Pameters chapter in the Cisco DCNM Interfaces Configuration Guide, Release 4.0 for information on IP address fields.

Additional References

For additional information related to implementing IP, see the following sections:

•Related Documents

•Standards

Related Documents

Related Topic	Document Title
IP CLI commands	Cisco NX-OS Unicast Routing Command Reference, Release 4.0

Standards

Standards	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—