Online Insertion And Removal - Cisco 7301 Installation And Configuration Manual

Functional Overview
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.
Storing the MAC addresses for every slot in one central location means the addresses stay with the
Note
memory device on which they are stored.

Online Insertion and Removal

All port adapters and service adapters in the Cisco 7301 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.
As you disengage the port adapter from the router or switch, online insertion and removal (OIR)
Note
administratively shuts down all active interfaces in the port adapter.
OIR allows you to install and replace port adapters and service adapters while the router is operating;
you do not need to notify the software or shut down the system power, although you should not run traffic
through the port adapter you are removing while it is being removed. OIR is a method that is seamless
to end users on the network, maintains all routing information, and preserves sessions.
The following is a functional description of OIR for background information only; for specific
procedures for installing and replacing a port adapter or service adapter in a Cisco 7301 router, refer to
the online configuration note for each port adapter or service adapter.
Each port adapter or service adapter has a bus connector that connects it to the router. The connector has
a set of tiered pins in three lengths that send specific signals to the system as they make contact with the
port adapter or service adapter. The system assesses the signals it receives and the order in which it
receives them to determine if a port adapter or service adapter is being removed or inserted into the
system. From these signals, the system determines whether to reinitialize a new interface or shut down
a removed interface.
For example, when you insert a port adapter or service adapter, the longest pins make contact with the
port adapter or service adapter first, and the shortest pins make contact last. The system recognizes the
signals and the sequence in which it receives them.
When you remove or insert a port adapter or service adapter in a Cisco 7301 router, the pins send signals
to notify the system, which then performs as follows:
1.
2.
3.
Cisco 7301 Installation and Configuration Guide
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Rapidly scans the system for configuration changes.
Initializes all newly inserted port adapters or service adapters, noting any removed interfaces and
placing them in the administratively shutdown state.
Brings all previously configured interfaces on the port adapter back to the state they were in when
they were removed. Any newly inserted interface is put in the administratively shutdown state, as if
it was present (but not configured) at boot time. If a similar port adapter type is reinserted into a slot,
its ports are configured and brought online up to the port count of the original port adapter. (A
service adapter has no configurable ports.)
Chapter 3 Starting and Configuring the Router
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