Switch configuration

The process of building a switch configuration is as follows:

        co -l sc.conf.c
        do
                do
                        <edit sc.conf.c>
                        make sc
                while <compile/link errors>     # probably C syntax
                make auto
        while <sc errors>                       # erroneous configuration
        make install
        ci -u sc.conf.c

The man page sc.8 gives some indication of what sc does; however, the Makefile in the directory does most of it for you.

What you need to do is modify the files sc.conf.c (under RCS control of course), build the sc program, build the auto files by running sc, then install the generated switch configuration and hostinfo files in the standard place (currently /usr/groups/wanda/boot/hostinfo ). Separate targets sc, auto and install exist in the Makefile with appropriate dependencies, but (motherhood coming up) it is advised to do a ``make auto'' and ensure it worked before a ``make install''.

To build a configuration, use co -l to grab the lock on sc.conf.c, and build in THIS directory. Release lock when finished. IT IS VITAL we do not end up with different people using different versions of sc.conf.c. This is why this directory is outside the normal tools tree, to avoid multiple copies.

The format of sc.conf.c is fairly tedious, but a brief study should show it's main features - some example gloop below may help.

The sc program starts at the top level of the description (end of file) with a struct world, composed of switches, hosts and gateways; these in turn are arrays of struct swtch, struct portc (this includes hosts), and struct gateway; a struct swtch is an array of struct portc. The macros PD() and HS() are used to define ports and hosts respectively, which then should be included in a switch or the list of hosts as appropriate.

It might be nice if this structure was actually built by parsing some simpler text file at run time - volunteers required. Further the sc program (apart from main) is "OO" in that it is trivial to have it deal with a number of worlds.

sc builds a sub directory auto containing an automatically generated hostinfo file, <hostname>.auto, and switch configuration files, <switch>-wdbc.c. Summary files F_READABLE and F_ROUTES are also produced for human consumption. The old auto subdirectory is renamed auto.BCK.

sc.conf.c format

Some examples of the format of entries are given below, although only looking at sc.conf.c will make it obvious what is going on.

Hosts and port controllers

Port          FSN,    MSNL address,    line to, public gate,
PD(hake,"hake",22, 128,232,132,144, &p_bummalo, ETHER | ALL, 0, 0, RAP | LRAP);

Port                     FSN,       MSNL address,   private gate,
PD( pilchard, "pilchard", 16, 128, 232, 132, 138, 0, ETHER | ALL, 0, 0, RAP);

Port                     FSN,       MSNL address,  link to,
PD( snook,    "snook",    10, 128, 232, 132, 142, &h_hyale, 0, 0, 0, 0);

Port                     FSN,       MSNL address,line to,  link gate,
PD( bummalo,  "bummalo",  21, 128, 232, 132, 131, &p_hake, 0, 0, ALL, RAP);

Host                            MSNL address,      private gateways
HS( hyale,    "hyale",    128, 232, 132,  41, 0, ETHER | ALL | FAIR, 0);

In these entries, the following flags are used:

        #define RAP  (1 << 0) /* Be a rarpd on a switch */
        #define WDBS (1 << 1) /* Be a WandaDumbBootServer */
        #define LRAP (1 << 2) /* Be a rarpd on a line */
        #define TTYS (1 << 3) /* Be a TTY Server */
        #define TTYC (1 << 4) /* Be a TTY Client */

Gateways

Ports (hosts) that act as gateways can either be public (i.e. willing to route for anyone) or private (i.e. only route for machine to which they are attached); there are two separate fields for private and public gateways in the port and host data structures.

The MSNL network associated with a particular gateway is defined by the struct gateway gates[] array. besides the obvious name, MSNL network and mask fields, there is a unique bit for each network (hence current sc tool is limited to 32 networks).

#define FAIR    (1 << 0)
#define CL      (1 << 1)
#define CFR     (1 << 2)
#define CBN     (1 << 3)
#define ETHER   (1 << 4)
#define PANDORA (1 << 5)

struct gateway gates[] = {
/* Own network here */
  {  ONE, "fair",    FAIR,    {128, 232, 128, 0}, {255, 255, 240, 0} },
/* Remainder which we gateway to here */
  {  ONE, "cl",      CL,      {128, 232,   0, 0}, {255, 255, 240, 0} },
  { MANY, "ether",   ETHER,   {128, 232,  64, 0}, {255, 255, 240, 0} }
};

The remaining field describe how the network is attached and how routeing should be done.

        #define ONE 1         /* Only one gateway to this network */
        #define MANY 0        /* Many gateways to this network */

A Switch

A switch entry consists of a (unique) name, MSNL base address if positional RARP (POSNRARP) is to be used , a null terminated list of port controllers (i.e. their structures)

static struct swtch b_switch = {
  "b",                           /* name */
  0,0,0,0,                       /* switch base address for POSNRARP */
  {
    &p_bass, &p_bloater, &p_bream, &p_bummalo,
    0                            /* null terminated array of ports */
  },
  0
};

static struct swtch grange_switch = {
  "grange",
  128,232,133,96,
  {
    &p_grange00, &p_grange01, &p_grange02, &p_grange03,
    &p_grange04, &p_grange05, &p_grange06, &p_grange07,
    &p_grange08, &p_grange09, &p_grange10, &p_grange11,
    &p_grange12, &p_grange13, &p_grange14, &p_grange15, 0
  },
  0
};