Online Insertion And Removal (Oir) - Cisco 7000 Hardware Installation And Maintenance

Functional Overview
However, the OIR feature makes it necessary to use a different method of handling the MAC
addresses in the Cisco 7000. OIR allows you to remove an interface processor and replace it with
another identically configured one. If the new interfaces match the current configuration (that of the
interfaces you removed), the system immediately brings them on line. In order to allow OIR, an
address allocator with 40 unique MAC addresses (5 interface processor slots times 8 possible ports
on each) is stored in an EEPROM on the RP. Each address is assigned to a specific slot/port in the
router regardless of whether or not an interface resides in that port. The MAC addresses are assigned
to the ports in sequence; the first address is assigned to port 0/0, the 20th to port 2/3, and the last
(40th) to port 4/7. This address scheme allows you to remove interface processors and insert them
into other routers without causing the MAC addresses to move around the network or be assigned to
multiple devices.
If the MAC addresses were stored on each interface processor, OIR would not function
Note
because you could never replace one interface with an identically configured one; the MAC
addresses would always be different.
Also, each time an interface was replaced, other devices on the network would have to update their
data structures with the new address and, if they did not do so quickly enough, could cause the same
MAC address to appear in more than one device at the same time.) Storing the MAC addresses on
the RP avoids these problems. When an interface is replaced with another interface with the same
configuration, there is no need for other devices in the network to update their data structures and
routing tables.
Storing the MAC addresses for every port in one central location on the RP also means that the MAC
addresses stay with the RP on which they are stored. If you replace the RP, the addresses of all ports
will change to those specified in the address allocator on the new RP. Because the system
configuration is also stored on the RP (in NVRAM) and stays with the RP when you remove it, you
will need to reenter the configuration if you replace the RP. (See the Timesaver note on page 1-30.)

Online Insertion and Removal (OIR)

The OIR function allows you to install and replace interface processors while the system is
operating; you do not need to notify the software or shut down the system power. All CxBus interface
processors support online insertion and removal. The following is a functional description of OIR
for background information only; for specific procedures for installing and replacing interface
processors on line refer to the chapter "Maintenance."
All CxBus interface processors support OIR. The RP and SP (or SSP) are required system
Caution
components that cannot be removed unless the system is shut down first. Removing an RP or SP (or
SSP) while the system is operating will cause the system to shut down or crash and may damage or
destroy memory files.
Each interface processor contains a bus connector with which it connects to the system backplane.
Each card connector comprises a set of tiered pins in three lengths. The pins send specific signals to
the system as they make contact with the backplane. The system assesses the signals it receives and
the order in which it receives them to determine what event is occurring and what task it needs to
perform, such as reinitializing new interfaces or shutting down removed ones. For example, when
inserting an interface processor, the longest pins make contact with the backplane first, and the
Product Overview 1-57