Perle 833IS, User Manual

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How the 833IS Works
64 Perle 833IS User Guide
Remote users can access file servers, Email, Mainframes, application servers, or any
other server that is on the LAN.
Incoming Call
Handling
When a call comes in on a channel of one of the BRI lines, the system identifies the
type of call as being either a digital or analog call. At this point, a check is made to
see if the resources required to handle the call are available. For example, a modem
is required if it is an analog call.
The System assigns the needed resources to the call. Resources are allocated on a
round robin basis to ensure that all resources are used equally. The resource does not
have to reside on the same physical card as the one on which the call came in. Once
the required resources have been identified, the call is accepted and is forwarded to
the appropriate resource. The calls are moved about in the system via a special bus
used for this purpose.
As an example, a call originating from a modem can come in on channel B2 of the
ISDN BRI line connected to the first port of the card in slot 1. This type of call will
require a modem. The system may locate an available modem on the card in slot 2.
The call would then be switched to this modem. All physical data would be sent and
received over the BRI line connected to port 1 of the first card but internally, the data
would be handled by the modem on the second card. This flexibility allows the
833IS to allocate its available resources in an effective and efficient manner.
Client
Handling
The Perle Server can support three types of clients. All can be supported
simultaneously by the Server.
Router Client
This client operates with the Server as a router. Perle Remote and Microsoft
Windows clients are examples of this type. They connect using their own remote
access capabilities. When communicating to the Perle Server, the client PC can be
set up to use either IPX, NetBEUI or IP protocol.
For messages originating from the client PC, the routing client will encapsulate the
IP, NetBEUI or IPX protocol in a PPP frame. The Server will remove the PPP
header, process the IP, NetBEUI or IPX header, and based on the addressing
information supplied at the protocol level, attach the appropriate MAC header. The
frame is then forwarded to the LAN.
For messages coming from the LAN and intended for a client PC, the Perle Server
will remove the MAC header, process the IP, NetBEUI or IPX headers and based on
the addressing information at the protocol level, forward the frame to the appropriate
client PC by encapsulating the message within a PPP frame.