Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
STRIP(4)		 BSD Kernel Interfaces Manual		      STRIP(4)

     strip -- Metricom Ricochet	packet radio wireless network device

     pseudo-device strip

     The strip driver takes outbound network packets, encapsulates them	using
     the Metricom "star	mode" framing, and sends the packets out an RS-232 in-
     terface to	a Metricom Ricochet packet radio.  Packets arriving from the
     packet radio via the serial link are decapsulated and then	passed up to
     the local host's networking stack.

     strip is an acronym for STarmode Radio IP.

     The strip interfaces can be created by using the ifconfig(8) create com-
     mand.  Each strip interface is a pseudo-device driver for the Metricom
     Ricochet packet radio, operating in peer-to-peer packet mode.

     In	many ways, the strip driver is very much like the sl(4)	SLIP pseudo-
     device driver.  A strip device is attached	to a tty line with
     slattach(8).  Once	attached, the interface	is configured via ifconfig(8).
     The major difference between the sl(4) SLIP pseudo-device driver and the
     strip driver is that SLIP works only between two hosts over a dedicated
     point-to-point connection.

     In	contrast, strip	sends packets to a frequency-hopping packet radio,
     which can address packets to any peer Metricom Ricochet packet radio,
     rather than just to a single host at the other end	of a point-to-point
     line.  Thus, one strip pseudo-device is usually sufficient	for any	ker-

     In	other respects,	a strip	interface is rather like an Ethernet inter-
     face.  Packets are	individually addressed,	and subsequent packets can be
     sent independently	to different MAC addresses.  However, the "star	mode"
     framing and MAC addressing	are not	in any way compatible with Ethernet.
     Broadcast or multicast to more than one packet radio is not possible, due
     to	the independent	frequency-hopping operation of the packet radios.  The
     interface flags IFF_POINTOPOINT and IFF_BROADCAST are not supported on
     the strip interface.

     In	other words, strip implements a	multiple-access, non-broadcast device,
     accessed via an RS-232 serial line, using a proprietary packet framing

     This version of the strip driver maps IP addresses	to Metricom Ricochet
     packet radio addresses using statically configured	entries	in the normal
     routing table.  These entries map IP addresses of peer packet radios to
     the MAC-level addresses.  The exact syntax	of this	mapping	and an example
     are discussed below.  The Internet	Assigned Numbers Authority (IANA) has
     allocated an ARP type code	for use	with STRIP.  A future version of this
     driver will support arp(4)	to obtain the IP address of reachable peer
     packet radios dynamically.

     This version of the STRIP driver requires static pre-configuration	of the
     mapping from IP addresses to packet radio MAC addresses.  The route(8)
     command should be used to bind a peer STRIP host's	packet radio IP	ad-
     dress to the peer's link-level packet radio address.

     Radio addresses are encoded using the hex equivalent of the packet	ra-
     dio's decimal ASCII address.  For example,	the following route command
     will configure a routing entry to a packet	radio with a MAC address of
     1234-5678,	and an IP address, reachable via the strip0	inter-

	   route add -host -link strip0:1:2:3:4:5:6:7:8

     Generalising from this example to other IP	addresses and to other 8-digit
     MAC addresses should be clear.

     The Metricom Ricochet packet radios can auto-baud at speeds up to 38.4K
     baud.  At higher speeds --	57600 or 115200	-- the packet radio cannot au-
     tobaud.  When running at high speeds, the packet radio's serial port
     should be manually	configured to permanently run at the desired speed.
     Use a terminal emulator and the Hayes command ATS304=115200 to set	the
     serial baudrate to	the specified number (or 0 for autobaud).  The command
     AT&W will then save the current packet radio state	in non-volatile	mem-

     Metricom Ricochet packet radios can operate in either "modem-emulation"
     mode or in	packet mode (i.e.  "star mode").  The strip driver automati-
     cally detects if the packet radio has fallen out of "star mode", and re-
     sets it back into "star mode", if the baud	rate was set correctly by

     arp(4), inet(4), sl(4), ifconfig(8), route(8), slattach(8)

     strip was originally developed for	the Linux kernel by Stuart Cheshire of
     Stanford's	Operating Systems and Networking group,	as part	of Mary
     Baker's MosquitoNet

     This strip	driver was ported to NetBSD by Jonathan	Stone at Stanford's
     Distributed Systems Group and first distributed with NetBSD 1.2.

     Currently,	strip is IP-only.  Encapsulations for AppleTalk	and ARP	have
     been defined, but are not yet implemented in this driver.

     strip has not been	widely tested on a variety of lower-level serial driv-

     The detection and resetting of packet radios that crash out of "star
     mode" does	not always work	in this	version	of the driver.	One workaround
     is	to kill	the slattach(8)	process, ifconfig(8) the strip interface down,
     and then start a new slattach and rerun ifconfig to enable	the interface

BSD			       December	5, 2004				   BSD


Want to link to this manual page? Use this URL:

home | help