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NATMIP(4)	       FreeBSD Kernel Interfaces Manual		     NATMIP(4)

NAME
     natmip -- IP over ATM PVCs

SYNOPSIS
     device atm
     options NATM

DESCRIPTION
     The NATM protocol stack includes support for IP over ATM.	Without	any
     additional	signalling stacks or other modules it is possible to build a
     CLIP (classical IP	over ATM) network based	on PVCs.

     An	ATM network card (en0 in this example) is configured for IP by some-
     thing like:

	   ifconfig en0	128.252.200.1 netmask 0xffffff00 up

     IP	routing	is done	with special interface routes (routes with directly
     reachable destinations) with a link layer gateway address.	 The link
     layer address specifies the ATM interface through which the destination
     can be reached, the virtual channel that connects to the destination and
     the ATM characteristics of	this channel.  The address part	of the link
     layer address (see	link_addr(3)) consists of a fixed part (the first 5
     bytes) and	a part that depends on the kind	of the PVC (UBR, CBR, VBR,
     ABR).  Multi-byte values are big-endian encoded: the bytes	with the lower
     numbers contain the higher	order bits.

	   byte	0	  Is a flag byte.  Currently only flag 0x20 is used.
			  When set, all	IP frames are LLC/SNAP encapsulated
			  before putting them into an AAL5 frame.  Setting
			  this flag is recommended and allows interoperability
			  with other CLIP implementations.  Note that BPF
			  works	only with LLC/SNAP encapsulation.

	   byte	1	  This is the VPI of the channel.

	   bytes 2...3	  VCI of the channel.  Must not	be zero.

	   byte	4	  Traffic type.	 One of	0 (UBR), 1 (CBR), 2 (ABR), 3
			  (VBR).

     The variable part for UBR connections may be either empty or three	bytes:

	   bytes 5...7	  Specifies the	peak cell rate for UBR.

     The variable part for CBR connections must	be three bytes:

	   bytes 5...7	  Specifies the	peak cell rate for CBR.

     The variable part for VBR connections must	be 9 bytes long	and specifies
     three values:

	   bytes 5...7	  Specifies the	peak cell rate for VBR.

	   bytes 8...10	  This is the sustainable cell rate.

	   bytes 11...13  The maximum burst size.

     The variable part for ABR connections must	be 19 bytes long and specifies
     the following values:

	   bytes 5...7	  Specifies the	peak cell rate for ABR.

	   bytes 8...10	  The minimum cell rate.

	   bytes 11...13  The initial cell rate.

	   bytes 14...16  The transient	buffer exposure.

	   byte	17	  The NRM value.

	   byte	18	  The TRM value.

	   bytes 19...20  The ADTF value.

	   byte	21	  The rate increase factor (RIF).

	   byte	22	  The rate decrease factor (RDF).

	   byte	23	  The cutoff decrease factor (CDF).

     To	add a PVC the route(8) utility can be used:

	   route add -iface <remote IP address>	-link <iface>:<lladdr>

     The iface is the ATM interface through which remote IP address can	be
     reached and lladdr	is the link layer address as a string of dot-sepa-
     rated, hexadecimal	bytes.

     NATM also supports	the old, original format.  This	consists of 4 byte
     link layer	addresses (and the channels are	implicit UBR):

	   byte	0	  Flags:
				0x01  use AAL5.
				0x02  if using AAL5, use an LLC/SNAP header.

			  Thus,	parameter 3 means AAL5 and LLC/SNAP encapsula-
			  tion (this is	the required setting for interworking
			  with other CLIP clients).  Note that BPF works only
			  with LLC/SNAP	encapsulation.

	   byte	1	  VPI for the channel

	   bytes 2...3	  VCI for the channel

EXAMPLES
     Suppose you have 3	hosts 128.252.200.1, 128.252.200.2 and 128.252.200.3
     connected by ATM through PVCs:

	   between 128.252.200.1 and 128.252.200.2: 0xc9 UBR
	   between 128.252.200.1 and 128.252.200.3: 0xca VBR
	   between 128.252.200.2 and 128.252.200.3: 0xcb CBR

     The parameters for	the VBR	channel	are: PCR 50000,	SCR 10000, MBS 10.
     The peak cell rate	for the	CBR channel is 100000.

     To	enable the links use the following commands:

     on	host 128.252.200.1:
	   ifconfig en0	128.252.200.1 netmask 0xffffff00 up
	   route add -iface 128.252.200.2 -link	en0:3.0.0.c9.0
	   route add -iface 128.252.200.3 -link	en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a

     on	host 128.252.200.2:
	   ifconfig en0	128.252.200.2 netmask 0xffffff00 up
	   route add -iface 128.252.200.1 -link	en0:3.0.0.c9.0
	   route add -iface 128.252.200.3 -link	en0:3.0.0.cb.1.1.86.a0

     on	host 128.252.200.3:
	   ifconfig en0	128.252.200.3 netmask 0xffffff00 up
	   route add -iface 128.252.200.1 -link	en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a
	   route add -iface 128.252.200.2 -link	en0:3.0.0.cb.1.1.86.a0

     This can also be done in rc.conf(5):

     on	host 128.252.200.1:
	   network_interfaces="lo0 en0"
	   ifconfig_en0="inet 128.252.200.1 netmask 255.255.255.0"
	   static_routes="host2	host3"
	   route_host2="-iface 128.252.200.2 -link en0:3.0.0.c9.0"
	   route_host3="-iface 128.252.200.3 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a"

     on	host 128.252.200.2:
	   network_interfaces="lo0 en0"
	   ifconfig_en0="inet 128.252.200.2 netmask 255.255.255.0"
	   static_routes="host1	host3"
	   route_host1="-iface 128.252.200.1 -link en0:3.0.0.c9.0"
	   route_host3="-iface 128.252.200.3 -link en0:3.0.0.cb.1.1.86.a0"

     on	host 128.252.200.3:
	   network_interfaces="lo0 en0"
	   ifconfig_en0="inet 128.252.200.3 netmask 255.255.255.0"
	   static_routes="host1	host2"
	   route_host1="-iface 128.252.200.1 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a"
	   route_host2="-iface 128.252.200.2 -link en0:3.0.0.cb.1.1.86.a0"

SEE ALSO
     en(4), fatm(4), hatm(4), natm(4), patm(4)

AUTHORS
     Chuck Cranor of Washington	University implemented the NATM	protocol layer
     along with	the EN ATM driver in 1996 for NetBSD.

FreeBSD	10.1			August 11, 2003			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | AUTHORS

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