Cisco BPX 8650, Installation And Configuration Manual

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Cisco BPX 8600 Series Installation and Configuration
Release 9.3.30, Part Number 78-12907-01 Rev. E0, May 2005
Chapter 1 The BPX Switch: Functional Overview
BPX Switch Operation
Note
The FRM-U or FRM-C cards for the IGX switch is supported only for network
interworking.
Figure 1-5 Frame Relay to ATM Service Interworking
Tiered Networks
Networks may be configured as:
•
Flat
All nodes perform routing and communicate fully with one another, or
•
Tiered
Interface shelves are connected to routing hubs, where the interface shelves are configured as
nonrouting nodes.
By allowing CPE connections to connect to a nonrouting node (interface shelf), a tiered network is able
to grow in size beyond that which would be possible with only routing nodes comprising the network.
Starting with Release 8.5, tiered networks support both BPX switch routing hubs and IGX switch routing
hubs. Voice and data connections originating and terminating on IGX switch interface shelves (feeders)
are routed across the routing network through the associated IGX switch routing hubs.
Tiered networks support multiservice connections, including Frame Relay, circuit data, voice, and ATM.
By allowing the customer’s equipment to connect to a nonrouting node (interface shelf), a tiered network
is able to grow in size beyond that which would be possible with only routing nodes.
Intermediate routing nodes must be IGX switches. IGX switch interface shelves are the only interface
shelves that can be connected to an IGX switch routing hub. With this addition, a tiered network provides
a multiservice capability (Frame Relay, circuit data, voice, and ATM).
Routing Hubs and Interface Shelves
In a tiered network, interface shelves at the access layer (edge) of the network are connected to routing
nodes by means of the feeder trunks as shown in Figure 1-6.
•
Routing hubs
Those routing nodes with attached interface shelves are referred to as routing hubs.
• Interface shelves
The interface shelves, sometimes referred to as feeders, are nonrouting nodes.
The routing hubs route the interface shelf connections across the core layer of the network.The interface
shelves do not need to maintain network topology nor connection routing information. This task is left
to their routing hubs.
This architecture provides an expanded network consisting of a number of nonrouting nodes
(interface shelves) at the edge of the network that are connected to the network by their routing hubs.
ATM network
Service
interworking
function
Frame
Relay Frame
Relay
ATM
CPE using a
standard, non-
service specific
convergence
protocol
H8226
CPE