Zhone Technologies IMACS Network Device - Manual (Page 55)

Zhone Technologies, Inc. IMACS Product Book, Version 4
March 2001 Page 51
3. FRAD Card
The 823160 Frame Relay Assembler/Disassembler (FRAD) user card provides eight ports for transport of low speed
data across Frame Relay Networks. The FRAD can encapsulate HDLC protocols (such as SDLC). Each port can be
independently configured for asynchronous, transparent synchronous data or HDLC.
When taking data from the on-board RS-232 port, the FRAD card supports speeds of 2.4, 4.8, 9.6, 14.4, 19.2, 28.8
and 38.4 Kbps, independently configured on a per port basis. The aggregate Frame Relay encapsulated traffic
coming out of the WAN card can be configured to transmit at 56Kbps or 64 Kbps.
When processing HDLC data, the flags and the CRC are removed before assembling the frames. For asynchronous
data, start and stop bits are removed before the frames are assembled. Other data is treated as a transparent data
stream and all bits will be encapsulated into transmitted frames. The FRAD card supports proprietary sub-
addressing over a PVC. This sub-addressing is transparent to the Frame Relay Transport Network, and allows
multiple ports on a single FRAD to share the same PVC, resulting in lower costs.
The FRAD card also maintains performance statistics detailing the number of frames transmitted, number of frames
received, number of octets transmitted, number of octets received, number of frames dropped before being received
during a 15 minute interval and a status field describing the conditional that caused the dropped packets (DTE port
down, loop back in progress or port in standby). All these performance statistics are gather for 24 hours, in 1-hour
intervals. The FRAD card also provides test frame generators for additional diagnostics.
In the application represented by the Figure 16 , the router on the left (at a remote office) is connected to the IMACS
via the FRAD card at 9.6Kbps, along with other voice traffic from a PBX. The router traffic is mapped onto a DS0
on the T1 link to the Central Office where it is separated by a DACS and directed towards a Frame Relay network
and switched/routed to the destination router at the headquarters. See Figure 15 for an illustration of the FRAD
Card’s capabilities and Table 16 for the FRAD Card’s specifications.