255-700-447
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PacketStar
®
PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
Chapter 3 System Features
User Interfaces
Frame Relay-to-ATM Interworking
Frame relay-to-ATM interworking is performed at the network level, Frame
Relay Implementation Agreement FRF.5, and at the service level, FRF.8. This
allows a PacketStar Multiservice Media Gateway to adapt and concentrate
traffic from one frame relay network and transmit it to other frame relay or
ATM networks. In this way, the Multiservice Media Gateway acts as a gate-
way between routers, remote-dial access servers, systems network architec-
ture (SNA) equipment, and other devices configured for frame relay opera-
tion.
FRF.5 Encapsulating
Frames
With FRF.5 network level interworking, frames are encapsulated within ATM
cells at the network ingress point and "tunneled" through the ATM network.
At the network egress point, the ATM cell headers are removed and the
frames are reassembled for delivery to a frame relay device.
FRF.8 Converting
Frames
With FRF.8 service level interworking, frames are converted into one or more
ATM cells at the network ingress point. At the network egress point, the ATM
cells are delivered to an ATM device. This conversion is compliant with both
the FRF.8 implementation agreement and the IEFT multiprotocol encapsula-
tion specifications (RFC 1490, RFC 1483). FRF.8 interworking is performed at
the end of the ATM network that connects to the frame relay device.
Note:
FRF.5 and FRF.8 are not interoperable and cannot be used at both
sides of a network. You may wish to use an FRF.8 approach for
applications involving interconnectivity between two frame relay
devices because the capabilities of FRF.8 include those that are
available with FRF.5.
Inverse Address
Resolution Protocol
(ARP)
The Inverse Address Resolution Protocol (ARP) feature using the FRF 8.1
specification provides packet translation between frame relay and ATM inter-
faces. The packet translation is available on both frame relay-to-ATM PVC
and frame-relay-to-ATM SPVC connections. For frame relay-to-ATM SPVC
connections, the ARP/inverse ARP to/from ATM side is treated as ATM PVC
ARP/inverse ARP.
Frame Relay-to-Frame Relay Interworking
In addition to frame relay-to-ATM interworking, it is possible to configure a
Multiservice Media Gateway for strictly frame relay operation. A frame relay-
to-frame relay connection can be made between two ports of a Multiservice
Media Gateway if both ports have frame relay capacity. In this case, frame
relay data received by one of the ports is converted to ATM cells for transmis-
sion across the backplane of the Multiservice Media Gateway, and then con-
verted back into frame relay for transmission from another port.
GR-303 Interface
The Telcordia Technologies General Requirements 303 (GR-303) standard
provides for both an open interface network architecture and a digital loop
carrier system that operates on T1 circuits. This standard allows a remote ter-
minal such as a central office PSAX system to flawlessly interface with a
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