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 |___ | UUUUUUThe 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:
SDLA has its own CPU and memory allowing it to work independently from a host PC. Furthermore, all communications protocols are implemented in firmware runnig on the SDLA, thus freeing the host's CPU from routine protocol handling tasks. This is particularly important in multiuser, multitasking environments, such as UNIX, where host CPU load is relatively high.
SDLA firmware is not stored on the adapter permanently. Instead, it is downloaded onto it each time adapter is initialized by a host PC. This allows the same SDLA card to support multiple communications protocols such as frame relay, X.25/HDLC, PPP, SDLC, Bisync, etc. by simply loading appropriate firmware modules.
Loadable nature of the SDLA firmware provides for an easy way to upgrade and/or add new protocols, as they become available, without replacing or reconfiguring hardware, even without rebooting your system.
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 ------------------------------------------------------------------------------