To assign multiple IP addresses to network interfaces, use the following command in interface configuration mode:
Command | Purpose |
ip address address I mask | Assign multiple IP addresses to network |
secondary | interfaces. |
5.2 Establish Address Resolution
A device in the IP can have both a local address (which uniquely identifies the device on its local segment or LAN) and a network address (which identifies the network to which the device belongs). The local address is more properly known as a data link address because it is contained in the data link layer (Layer 2 of the OSI model) part of the packet header and is read by data link devices (bridges and all device interfaces, for example). The more technically inclined will refer to local addresses as MAC addresses, because the Media Access Control (MAC)
To communicate with a device on Ethernet, you first must determine the
Once a media or MAC address is determined, the IP address/media address association is stored in an ARP cache for rapid retrieval. Then the IP datagram is encapsulated in a
5.2.1 Define a Static ARP Cache
ARP provides a dynamic mapping between IP addresses and media addresses. Because most hosts support dynamic address resolution, you generally do not need to specify static ARP cache entries. Completing this task installs a permanent entry in the ARP cache. The entry is used to translate
Optionally, you can specify that the software respond to ARP requests as if it was the owner of the specified IP address. You also have the option of specifying an interface when you define ARP entries.
Perform the following task in global configuration mode, to provide static mapping between IP addresses and media addresses.
Command | Purpose |
arp | Globally associate an IP address with a media |
| (hardware) address in the ARP cache. |
arp | Specify that the software respond to ARP |
[interface ] | requests as if it was the owner of the specified |
| interface. |
To display the ARP being used on a particular interface, use the show interface in top mode or global configuration mode. Use the show arp command in top or configuration mode to examine the contents of the ARP cache.
Configuring IP Routing
IP routing protocols are divided into two classes: Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs).
Note: The word gateway is often a part of a routing protocol’s name, since many routing protocol specifications refer to routers as gateways. However, a protocol translation gateway is usually defined by the Open System Interconnection (OSI) reference model as a Layer 7 device, whereas a router is a Layer 3 device, and routing protocol activities occur at the Layer 3 level.
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