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1. WANPIPE Basics

WANPIPE (tm) is an add-on product for Linux operating system that together with Sangoma's SDLA card allows to route TCP/IP traffic over a wide variety of data links, such as leased lines, frame relay or X.25 public data networks.

WANPIPE (tm) is implemented as a set of kernel loadable modules and related utilities providing for the full integration of WAN protocols into Linux protocol stack. WANPIPE modules form a two-layer hierarchy, as shown below.

     +-------------- /dev/sdla0
     |  +----------- /dev/sdla1
     |  |  +-------- /dev/sdla2     /\/\/\/\/\/\/\/\/\/\/\/\/\
     |  |  |  . . . . . . . . .     |  Linux protocol stack  |
     |  |  |  .  +-- /dev/sdla7     +------------------------+
     |  |  |  .  |                        ^   ^   ^   ^         LINUX
     |  |  |  .  | ====================== | = | = | = | =================
   +----------------+  +--------------------+ |   |   |
   |                |  |                    | |   |   |
   |                |--| Frame Relay Module |---+ |   |
   |                |  |                    |   | |   |
   |                |  +--------------------+   |---+ |
   |   SDLA Driver  |------|    PPP Module      |   | |    WANPIPE (tm)
   |                |      +--------------------+   |---+
   |                |----------|    X.25 Module     |   |
   |                |          +--------------------+   |
   |                |--------------|     SDLC Module    |
   +----------------+              +--------------------+
     |  |  |  .  |           Protocol-specific modules
     |  |  |  .  | ======================================================
     |  |  |  .  |     +---------+                       SDLA HARDWARE
     |  |  |  .  +-----| SDLA #8 #---> to mainframe
     |  |  |           |___      |
     |  |  |               UUUUUU
     |  |  |           +---------+
     |  |  +-----------| SDLA #3 #---> to X.25 network
     |  |              |___      |
     |  |                  UUUUUU
     |  |              +---------+
     |  +--------------| SDLA #2 #---> to leased line
     |                 |___      |
     |                     UUUUUU
     |                 +---------+
     +-----------------| SDLA #1 #---> to frame relay network
                       |___      |
                           UUUUUU
The SDLA Driver is protocol-independent and responsible for managing SDLA hardware. It also provides interface to protocol-specific modules for user-level applications through device the nodes in /dev directory.

All protocol-dependent functionality is implemented in protocol-specific modules concerning with WAN protocol specifics and interfacing with Linux protocol stack.

Modular design of WANPIPE (tm) allows to conserve system resources as modules can be loaded and unloaded dynamically. Also new WAN protocols can be easily added to existing configuration by simply installing additional protocol- spesific modules.

SDLA Driver can support up to eight SDLA cards allowing you to have up to eight independent WAN links at the same time.

Sangoma's SDLA is an intelligent multiprotocol communications adapter for IBM PC-compatible personal computers. SDLA can provide PC connectivity to various data links including frame relay, X.25, PPP, HDLC, SDLC, Bisync, etc.

Some of the key features of SDLA are:

Currently the SDLA family includes four cards: All SDLA cards use 8-kilobyte dual-port memory window to transfer data to and from the host PC. No DMA to worry about! Memory window can be set at almost any 8 kilobyte boundary within PC address range from A0000 to F0000 (hex). Memory window location is set in software, not by jumpers.

SDLA cards (excluding S502A) can generate an interrupt request (IRQ) to the host PC when host's attention is required. S502E card offers selection of 4 IRQ levels set by jumpers, while S508 allows to choose from 7 software- settable IRQ levels.

Each SDLA card occupies 3 to 4 consecutive I/O ports (depending on the adapter type). These ports are used by the adapter exclusively (i.e. they can not be shared with other hardware). S502A and S502E cards can be configured for four different I/O port addresses allowing to install up to four adapters per PC, while S508 and S503 give you a choise of 8 different I/O port addresses, increasing maximum number of installed adapters to eight.

When multiple SDLA cards are installed in one machine, each card has to be assigned unique I/O port, memory window and, optionally, IRQ line. However, when adapter is shut down, both its memory window and IRQ line are freed and can be used by other hardware.

All adapters use 8-bit data path. This is not a limitation, but rather convenience. 8-bit data bus provides throughput of about 1 Mbyte per second, which is sufficient even for communications at T-1/E-1 speeds, while allowing SDLA to be installed in any PC slot, including 8-bit slots found on some older motherboards.

The following table compares hardware characteristics of different SDLA types.

------------------------------------------------------------------------------
Adapter type                    S502A     S502E      S503       S508
------------------------------------------------------------------------------
Number of communication ports   1         1          1          2
Interface type                  RS232     RS232/V35  RS232/V35  RS232/V35
Maximum speed, kbps             64        112        128        2048
Interrupt generation            no        2,3,5,7    2-5,7      3,4,5,7,10-12
On-board CPU speed, MHz         up to 8   up to 10   up to 10   up to 16
On-board memory size, kbytes    32/64     32/64      64         128/256
Dual-port memory window size    8K        8K         8K         8K
Data path width, bit            8         8          8          8
Max. number of cards installed  4         4          8          8
------------------------------------------------------------------------------

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