1-33
Cisco 7100 Series VPN Router Installation and Configuration Guide
78-6341-03
Chapter 1 Overview
Functional Overview
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 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.
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
The modular port adapter installed in Cisco 7100 series VPN routers supports OIR. This function allows
you to install and replace a port adapter while the router is operating; you do not need to notify the
software or shut down the system power. This provides 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 in a Cisco 7100 series VPN router, see the
configuration note that ships with each port adapter.
Each port adapter has a bus connector that connects it to the router. Each 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.
The system assesses the signals it receives and the order in which it receives them to determine if a port
adapter is being removed or inserted into the router. 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, the longest pins make contact with the port 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 in a Cisco 7100 series VPN router, the port adapter pins send
signals to notify the system, which then performs as follows:
1.
Rapidly scans the system for configuration changes.
2.
Initializes all newly inserted port adapters, noting any removed interfaces and placing them in the
administratively shutdown state.
3.
Brings all previously configured interfaces on the port adapter back to the state they were in when
they were removed. Any newly inserted interfaces are put in the administratively shutdown state, as
if they were present (but not configured) at boot time. If a similar port adapter type is reinserted into
a slot, its ports are configured and brought on line up to the port count of the original port adapter.
Peripheral Component Interconnect Buses
All interfaces connect to two Peripheral Component Interconnect (PCI) buses on the router that provide
a path to packet I/O memory and the network processor. Interfaces in slots 1, 3, and 5 use PCI bus 0 and
interfaces in slots 0, 2, and 4 use PCI bus 1. For port adapters that are installed in the modular port
adapter slots (slot 3 or slot 4), use the guidelines described in
Appendix A, “Modular Port Adapter
Configuration Guidelines,”
to ensure sufficient bandwidth.
The maximum recommended bandwidth points on each PCI bus is 600 points. For best performance we
recommend that you avoid using port adapters that exceed the total available bandwidth for your router.
