ND SatCom SKYWAN IDU 7000, Manual

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126 Network Design and Engineering Guide 2010-10-26
Data Networking
SkyWAN
®
Frame Relay Networking Features
4.3.2 Basic Frame Relay Services
Basic Frame Relay is supported according to the Frame Relay Forum standards FRF 1.2 (UNI)
and FRF 2.2 (NNI). Frame Relay Connectivity is based on the configuration of Permanent Vir-
tual Circuits (PVC) which logically link serial data ports of
Sky WAN
®
IDUs across the satellite
network.
Up to 300 PVCs can be defined on each serial port. Each PVC is locally identified on a serial
port by its local Data Link Connection Identifier (DLCI). The configured PVCs allow attached
Frame Relay Access Devices to exchange data with remote devices via the
Sky WAN
®
Frame
Relay network.
For each unicast PVC the following parameters have to be specified in the FR circuit table:
-
Local serial port number
- Local DLCI number
- Remote IDU SLL address
- Remote IDU serial port number
- Remote DLCI number
This PVC definition is by nature unidirectional. For a bidirectional PVC a matching entry has to
be defined in the circuit table of the remote IDU.
A Frame Relay connection in a Sky WAN
®
network is always a direct single hop connection be-
tween the IDUs. Double hop connectivity via an intermediate IDU is not supported for Frame
Relay services. Besides connections across the satellite network
Sky WAN
®
IDUs support also
local switching, i.e. PVCs connecting two serial ports on the same IDU.
In addition to unicast connections also multicast connections are possible. For a multicast PVC
a remote multicast group must be defined instead of remote IDU address and port number. Up
to 32 multicast groups are supported in a
Sky WAN
®
network. Stations which should receive
multicast data over the satellite interface and forward these data over one of their serial inter-
faces need a multicast group filter definition on at least one of their serial interfaces. This defi-
nition specifies which multicast group data flows should be forwarded over a specific serial port.
The Sky WAN
®
IDU supports Local Management Interface (LMI) procedures, which provide
regular status reports about the configured PVCs to attached Access Devices. The following
LMI standards are supported:
- ANSI T1.617a Annex D
- ITU-T Q.933 Annex A
- LMI Vendor Forum
A proprietary Node Status Message protocol allows the IDUs to exchange status information
about the status of activated serial ports and configured multicast group filter definitions on
these ports.