Frame Relay Multi-Point

Frame Relay multiplexing for up to 32 ports and 16 remote sites

Host site SRX Multiplexer

Remote site SR Multiplexer


Port Specifications
Operating Modes
Network Specifications
Network Management Port
Network Management Port Commands



The DCB Frame Relay firmware cartridge for the SRX and SR multiplexers allows your async terminals and PCs cost effective access to public frame relay networks. Point to multipoint connections can be made at speeds up to 38,400 bps per port with composite link speeds to 128 Kbps.

Frame relay networks can offer very low cost communications links. Most international, nationwide and regional telephone companies offer frame relay. Frame relay services are priced competitively because frame relay protocols share the network bandwidth very efficiently among many users.

Public frame relay networks pass data in packets that are error corrected at the end points by the customer equipment, in this case, the DCB SRX and SR. By placing the error correction burden on the customer's end point equipment, data is passed through the network very quickly. Frame relay protocol is similar to X.25 protocol without the one to two second end-to-end delay.

Frame relay networks are typically priced at a flat rate per end point, regardless of the distances between the customer locations. Frame relay service is delivered to the customer at a given access rate, such as 56 Kbps.

The DCB SRX multiplexer is used at the host site and is available in 8, 16, 24 or 32 ports. The DCB SR multiplexer is used at the remote sites and is available in 1, 4, 8, 16, 24 and 32 ports. The SRX and SR have a built-in RS-232-D Network Management Port for local or remote setup and management. The SRX also includes an LCD front panel. The Network Management Port connects to any async terminal, or to a PC with a serial communications program. Each port can be configured separately for speed and flow control.

More than one SRX can share a single 56/64/128 Kbps line at the host by using an MSU-4D line sharing unit. More than one SRX can share a line faster than 128 Kbps by using a DCB frad.

For installations with multiple host SRXs, the multiplexers can be rackmounted and the DCB Access Switch is recommended. The Access Switch makes local and remote management easy and convenient.

Point-To-Multipoint Frame Relay
Asynchronous Statistical Multiplexing
Host (SRX): 8, 16, 24 or 32 channels
Drops (SR): 1, 4, 8, 16, 24 or 32 ports
Up to 16 remote drops
Port Specifications
Data Format:
1 Start bit
8 Data bits including parity if used
1 Stop bit
10 Bits total
Rates: 300, 1200, 2400, 4800, 9600, 19200 & 38400 bps individually selectable per port
Interface: CCITT V.24, RS-232-D
Connnectors: RJ-45 (8-wire)
Buffering: 64K dynamically allocated
Port Flow Control: Set on a per port basis
Clear to Send
Busy High
Busy Low
Operating Modes
Normal on-line multiplexing
Network loopback
Network Specifications
Frame Relay composite protocol
Rates: Up to 128 Kbps synchronous
Interface: CCITT V.24, RS-232-D
Error Correction: Automatic retransmission
Connnectors: RJ-45 (8-wire)
Network to DSU cable supplied
Indicators (front panel)
Power, Activity, Line Error, Modem Ready, Option
Host: Front panel push buttons for Next, ->, INCR, OK, RESET
Drops: Front panel port 1 setup, loopback, reset
Network Management Port
Interface: CCITT V.24, RS-232-D
Connnectors: RJ-45 (8-wire)
Network Management Port Commands

Help Screen
Remote Test Message with Port Loopback
Monitor Transmit at Local Port
Monitor Receive at Local Port
Network Loopbacks
Flow Control
Active Set Time
Ping Port (echo time)

Show Configuration
Show Network Configuration
Configure Ports
Port Loopback
Device Type
Capture Port
Copy Port
Send Test Message
Activity Counters
Power requirements: 120 VAC, 30-43 Watts, .25-.36 Amps
10 1/4" x 9 3/4" x 2 1/4" (4, 8 or 16 channels)
10 1/4" x 9 3/4" x 4 1/2" (24 or 32 channels)
Internal DSU/CSU with 56, 19.2 & 9.6 Kbps
MSU-4D for more than 1 multiplexer on a 56/64/128 Kbps link at host.
DCB multiport FRADS for more than 1 multiplexer on a single link greater than 128 Kbps at host.

Rear view of 16 channel SRX and SR Multiplexer


Data Comm for Business Inc.
2949 County Road 1000 E
Dewey, Il 61840
Voice: 217-897-6600
Toll Free: 800-4-DCB-NET
Toll Free: 800-432-2638
Email: Contact Page
Fax: 217-897-8023
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