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Cisco 7201 Installation and Configuration Guide
OL-11364-04
Chapter 3 Starting and Configuring the Router
Functional Overview
The following example shows the display for the first port on the Gigabit Ethernet port:
Router#
show interfaces
g0/0
GigabitEthernet0/0 is up, line protocol is up
Hardware is MV64460 Internal MAC, address is 0019.56c5.2adb (bia0019.56c5.2adb)
Internet address is 11.1.1.1/16
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 45/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is RJ45
output flow-control is XON, input flow-control is XON
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:07:03, output 00:00:07, output hang never
Last clearing of "show interface" counters 00:00:04
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
(display text omitted)
For complete descriptions and instructions of the commands used to configure your Cisco 7201 router,
refer to the Cisco IOS Configuration Fundamentals Configuration Guide and Cisco IOS Configuration
Fundamentals Command Reference publications at the following URL:
http://www.cisco.com/web/psa/products/index.html?c=268438303
MAC Address
All LAN interfaces (ports) require unique MAC addresses, also known as hardware addresses. Typically,
the MAC address of an interface is stored on a memory component that resides directly on the interface
circuitry; however, the OIR feature requires a different method. (For a description of OIR, see the
“Online Insertion and Removal” section on page 3-4
.)
Using OIR, you can remove a port adapter and replace it with another identically configured one. If the
new port adapter matches the port adapter you removed, the system immediately brings it online. In order
to enable OIR, an address allocator with unique MAC addresses is stored in an EEPROM on the system
board. Each address is reserved for a specific port and slot in the router regardless of whether or not a
port adapter resides in that slot. The MAC address for the port adapter slot in the Cisco 7201 is
designated slot 0
.
You can remove a port adapter and insert it into another router without causing the
MAC addresses to move around the network or be assigned to multiple devices.
Note that if the MAC addresses were stored on each port adapter, OIR would not function because you
could never replace one port adapter with an identical one; the MAC addresses would always be
different. Also, each time a port adapter was replaced, other devices on the network would have to update
their data structures with the new address. If the other devices did not update quickly enough, the same
MAC address could appear in more than one device at the same time.
Note
Storing the MAC addresses for every slot in one central location means the addresses stay with the
memory device on which they are stored.
