Cisco 7200 VXR - Manual (Page 57)

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Cisco 7200 VXR Installation and Configuration Guide
OL-5013-09
Chapter 1 Cisco 7200 VXR Product Overview
Functional Overview
The following example shows the display for the first port on the Fast Ethernet port adapter in port
adapter slot 5:
Router# show interface fastethernet 5/0
FastEthernet5/0 is up, line protocol is up
Hardware is DEC21140, address is 0000.000.0000 (bia 0000.0000.0000)
Internet address is 0.0.0.0
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type:ARPA, ARP Timeout 04:00:00
(display text omitted)
For complete descriptions and instructions of the commands used to configure your Cisco 7200 VXR
router, refer to the Configuration Fundamentals Configuration Guide and Configuration Fundamentals
Command Reference publications, which are available on Cisco.com or the Documentation DVD.
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 1-57 .)
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 EPROM on the router
midplane. Each address is reserved for a specific port and slot in the router regardless of whether a port
adapter resides in that slot. The MAC addresses are assigned to the slots in sequence. The first address
is assigned to slot 0, and the last address is assigned to slot 4 in the Cisco 7204VXR or to slot 6 in the
Cisco 7206VXR. Using this address scheme, you can remove port adapters and insert them into other
routers 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.
Online Insertion and Removal
All port adapters and service adapters in the Cisco 7200 VXR routers support online insertion and
removal (OIR). However, it is wise to shut down the interface before removing a port adapter that has
active traffic moving through it. Removing a port adapter while traffic is flowing through the ports can
cause system disruption. Once the port adapter is inserted, the ports can be brought back up.