1Generic HDLC layer
  2Krzysztof Halasa <khc@pm.waw.pl>
  3
  4
  5Generic HDLC layer currently supports:
  61. Frame Relay (ANSI, CCITT, Cisco and no LMI)
  7   - Normal (routed) and Ethernet-bridged (Ethernet device emulation)
  8     interfaces can share a single PVC.
  9   - ARP support (no InARP support in the kernel - there is an
 10     experimental InARP user-space daemon available on:
 11     http://www.kernel.org/pub/linux/utils/net/hdlc/).
 122. raw HDLC - either IP (IPv4) interface or Ethernet device emulation
 133. Cisco HDLC
 144. PPP
 155. X.25 (uses X.25 routines).
 16
 17Generic HDLC is a protocol driver only - it needs a low-level driver
 18for your particular hardware.
 19
 20Ethernet device emulation (using HDLC or Frame-Relay PVC) is compatible
 21with IEEE 802.1Q (VLANs) and 802.1D (Ethernet bridging).
 22
 23
 24Make sure the hdlc.o and the hardware driver are loaded. It should
 25create a number of "hdlc" (hdlc0 etc) network devices, one for each
 26WAN port. You'll need the "sethdlc" utility, get it from:
 27	http://www.kernel.org/pub/linux/utils/net/hdlc/
 28
 29Compile sethdlc.c utility:
 30	gcc -O2 -Wall -o sethdlc sethdlc.c
 31Make sure you're using a correct version of sethdlc for your kernel.
 32
 33Use sethdlc to set physical interface, clock rate, HDLC mode used,
 34and add any required PVCs if using Frame Relay.
 35Usually you want something like:
 36
 37	sethdlc hdlc0 clock int rate 128000
 38	sethdlc hdlc0 cisco interval 10 timeout 25
 39or
 40	sethdlc hdlc0 rs232 clock ext
 41	sethdlc hdlc0 fr lmi ansi
 42	sethdlc hdlc0 create 99
 43	ifconfig hdlc0 up
 44	ifconfig pvc0 localIP pointopoint remoteIP
 45
 46In Frame Relay mode, ifconfig master hdlc device up (without assigning
 47any IP address to it) before using pvc devices.
 48
 49
 50Setting interface:
 51
 52* v35 | rs232 | x21 | t1 | e1 - sets physical interface for a given port
 53                                if the card has software-selectable interfaces
 54  loopback - activate hardware loopback (for testing only)
 55* clock ext - both RX clock and TX clock external
 56* clock int - both RX clock and TX clock internal
 57* clock txint - RX clock external, TX clock internal
 58* clock txfromrx - RX clock external, TX clock derived from RX clock
 59* rate - sets clock rate in bps (for "int" or "txint" clock only)
 60
 61
 62Setting protocol:
 63
 64* hdlc - sets raw HDLC (IP-only) mode
 65  nrz / nrzi / fm-mark / fm-space / manchester - sets transmission code
 66  no-parity / crc16 / crc16-pr0 (CRC16 with preset zeros) / crc32-itu
 67  crc16-itu (CRC16 with ITU-T polynomial) / crc16-itu-pr0 - sets parity
 68
 69* hdlc-eth - Ethernet device emulation using HDLC. Parity and encoding
 70  as above.
 71
 72* cisco - sets Cisco HDLC mode (IP, IPv6 and IPX supported)
 73  interval - time in seconds between keepalive packets
 74  timeout - time in seconds after last received keepalive packet before
 75            we assume the link is down
 76
 77* ppp - sets synchronous PPP mode
 78
 79* x25 - sets X.25 mode
 80
 81* fr - Frame Relay mode
 82  lmi ansi / ccitt / cisco / none - LMI (link management) type
 83  dce - Frame Relay DCE (network) side LMI instead of default DTE (user).
 84  It has nothing to do with clocks!
 85  t391 - link integrity verification polling timer (in seconds) - user
 86  t392 - polling verification timer (in seconds) - network
 87  n391 - full status polling counter - user
 88  n392 - error threshold - both user and network
 89  n393 - monitored events count - both user and network
 90
 91Frame-Relay only:
 92* create n | delete n - adds / deletes PVC interface with DLCI #n.
 93  Newly created interface will be named pvc0, pvc1 etc.
 94
 95* create ether n | delete ether n - adds a device for Ethernet-bridged
 96  frames. The device will be named pvceth0, pvceth1 etc.
 97
 98
 99
100
101Board-specific issues
102---------------------
103
104n2.o and c101.o need parameters to work:
105
106	insmod n2 hw=io,irq,ram,ports[:io,irq,...]
107example:
108	insmod n2 hw=0x300,10,0xD0000,01
109
110or
111	insmod c101 hw=irq,ram[:irq,...]
112example:
113	insmod c101 hw=9,0xdc000
114
115If built into the kernel, these drivers need kernel (command line) parameters:
116	n2.hw=io,irq,ram,ports:...
117or
118	c101.hw=irq,ram:...
119
120
121
122If you have a problem with N2, C101 or PLX200SYN card, you can issue the
123"private" command to see port's packet descriptor rings (in kernel logs):
124
125	sethdlc hdlc0 private
126
127The hardware driver has to be build with #define DEBUG_RINGS.
128Attaching this info to bug reports would be helpful. Anyway, let me know
129if you have problems using this.
130
131For patches and other info look at:
132<http://www.kernel.org/pub/linux/utils/net/hdlc/>.