Table of Contents
BPX Switch Operation
Colocating Routing Hubs and Interface Shelves
The trunk between an interface shelf and the routing network is a single point of failure; therefore, the
interface shelves can be colocated with their associated hub node. Card level redundancy is supported
by the Y-Cable redundancy for the BXM, BNI, and UXM.
Network Management
Communication between CPE devices and the routing network is provided in accordance with Annex G
of Recommendation Q.2931. This is a bidirectional protocol for monitoring the status of connections
across a UNI interface. (Note: the feeder trunk uses the STI cell format to provide the ForeSight rate
controlled congestion management feature.)
Communication includes the real-time notification of the addition or deletion of a connection segment
and the ability to pass the availability (active state) or unavailability (inactive state) of the connections
crossing this interface.
A proprietary extension to the Annex G protocol is implemented that supports the exchange of node
information between an interface shelf and the routing network. This information is used to support the
IP Relay feature and the Robust Update feature used by network management.
Network Management access to the interface shelves is through the IP Relay mechanism using SNMP
or TFTP or by direct attachment to the interface shelf. The IP Relay mechanism relays traffic from the
routing network to the attached interface shelves. No IP Relay support is provided from the interface
shelves into the routing network.
The BPX routing hub is the source of the network clock for its associated feeder nodes. Feeders
synchronize their time and date to match their routing hub.
Robust Object and Alarm Updates are sent to a network manager that has subscribed to the Robust
Updates feature. Object Updates are generated whenever an interface shelf is added or removed from the
hub node and when the interface shelf name or IP Address is modified on the interface shelf. Alarm
Updates are generated whenever the alarm state of the interface shelf changes between Unreachable,
Major, Minor, and OK alarm states.
An interface shelf is displayed as a unique icon in the Cisco WAN Manager topology displays. The colors
of the icon and connecting trunks indicate the alarm state of each.
Channel statistics are supported by FRM, ASI, UXM, and MGX 8220 endpoints. The Broadband
Network Interface (BNI) card does not support channel statistics. Trunk Statistics are supported for the
feeder trunk and are identical to the existing BNI trunk statistics.
Inverse Multiplexing ATM
Where greater bandwidths are not needed, the Inverse Multiplexing ATM (IMA) feature provides a
low-cost trunk between two BPX switches.
The IMA feature allows BPX switches to be connected to one another over any of the eight T1 or E1
trunks provided by an IMATM module on an MGX 8220 shelf. A BNI or BXM port on each BPX switch
is directly connected to an IMATM module in an MGX 8220 by a T3 or E3 trunk. The IMATM modules
are then linked together by any of the eight T1 or E1 trunks. IMA is also configurable on lines.
Refer to the Cisco MGX 8220 Reference and the Cisco WAN Switching Command Reference publications
for further information.
Cisco BPX 8600 Series Installation and Configuration
1-18
Chapter 1
The BPX Switch: Functional Overview
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Table of Contents
Troubleshooting
