Pathbuilder S600 With Stx Overview; Pathbuilder S600 Stx Architecture - 3Com 3C63100-AC-C - PathBuilder S600 Bridge/router Reference Manual

20 C 1: S
HAPTER YSTEM
PathBuilder S600 with
STX Overview
PathBuilder S600 STX
Architecture
D
ESCRIPTION
Each transmission direction in a virtual circuit is referred to as a virtual channel.
Virtual channels are then grouped into virtual paths between two ports. The
channels and paths are assigned numbers: VPIs (Virtual Path Indicators) and VCIs
(Virtual Channel Indicators). Each ATM cell (a fixed-length unit of data over ATM)
is assigned to a virtual circuit by including the circuit's VPI/VCI in the cell's header.
This is then used to steer the cell through an ATM unit and the ATM network.
The PathBuilder S600 WAN access switch with Super Transport eXchange (STX)
provides enhanced switching and traffic management capabilities. It is designed to
concentrate, aggregate, and switch local ATM and legacy traffic over ATM
wide-area services for affordable ATM services access.
The PathBuilder S600 with STX requires software Release 2.0 or higher.
The modular architecture of the PathBuilder S600 with STX is designed to
accommodate a wide range of interfaces and support a comprehensive set of
applications. The core component of the unit is a 1.6 Gbps cell bus backplane
where all traffic is carried in the form of ATM cells. The PathBuilder S600 with STX
accommodates up to two power supplies (AC110/220 VAC and DC-48 VDC) in a
redundant configuration.
The overall design philosophy of the PathBuilder S600 with STX is to facilitate the
transfer of cells on and off the bus backplane with enhanced traffic management
and switching capabilities. All packet to cell segmentation and reassembly (SAR)
functions are performed on each of the application modules (Ethernet, Frame
Relay, and CBR), thereby ensuring efficient cell transfer through the system, (See
Figure 2.) Additional SAR power is added each time a non-ATM interface module
is added.
Figure 2 PathBuilder S600 with STX Cell Bus Architecture
10bt(2)
Ethernet
Because the STX module allows any-to-any port switching, there is no distinction
between port and trunk modules for the PathBuilder S600 with STX. Thus, the slot
assignments are as follows:
V.35(4), HSSI(1), T1(8)
Frame
Relay
STX
T1/E1, IMA(8), OC3/STM-1,
T1/E1(4/8) HSSI, DS3/E3
CBR
MCPU
10bt, RS232, SLIP
ATM