219 lines
6.0 KiB
Groff
219 lines
6.0 KiB
Groff
.\" $FreeBSD$
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.\"
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.Dd August 11, 2003
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.Dt NATMIP 4
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.Os
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.Sh NAME
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.Nm natmip
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.Nd IP over ATM PVCs
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.Sh SYNOPSIS
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.Cd "device atm"
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.Cd "options NATM"
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.Sh DESCRIPTION
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The NATM protocol stack includes support for IP over ATM.
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Without any
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additional signalling stacks or other modules it is possible to build
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a CLIP (classical IP over ATM) network based on PVCs.
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.Pp
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An ATM network card (en0 in this example) is configured for IP by something
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like:
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.Pp
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.Dl # ifconfig en0 128.252.200.1 netmask 0xffffff00 up
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.Pp
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IP routing is done with special interface routes (routes with directly
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reachable destinations) with a link layer gateway address.
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The link layer address specifies the ATM interface through which the
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destination can be reached, the virtual channel that connects to the
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destination and the ATM characteristics of this channel.
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The address part of the link layer address (see
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.Xr link_addr 3 )
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consists of a fixed part (the first 5 bytes) and a part that
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depends on the kind of the PVC (UBR, CBR, VBR, ABR).
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Multi-byte values
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are big-endian encoded: the bytes with the lower numbers contain the
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higher order bits.
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.Bl -tag -width "bytes 12...12" -offset indent
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.It byte 0
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Is a flag byte.
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Currently only flag 0x20 is used.
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When set, all IP frames are LLC/SNAP encapsulated before putting them into
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an AAL5 frame.
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Setting this flag is recommended and allows interoperability with other
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CLIP implementations.
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Note that BPF works only with LLC/SNAP encapsulation.
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.It byte 1
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This is the VPI of the channel.
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.It bytes 2...3
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VCI of the channel.
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Must not be zero.
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.It byte 4
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Traffic type.
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One of 0 (UBR), 1 (CBR), 2 (ABR), 3 (VBR).
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.El
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.Pp
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The variable part for UBR connections may be either empty or three bytes:
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.Bl -tag -width "bytes 12...12" -offset indent
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.It bytes 5...7
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Specifies the peak cell rate for UBR.
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.El
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.Pp
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The variable part for CBR connections must be three bytes:
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.Bl -tag -width "bytes 12...12" -offset indent
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.It bytes 5...7
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Specifies the peak cell rate for CBR.
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.El
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.Pp
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The variable part for VBR connections must be 9 bytes long and specifies three
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values:
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.Bl -tag -width "bytes 12...12" -offset indent
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.It bytes 5...7
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Specifies the peak cell rate for VBR.
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.It bytes 8...10
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This is the sustainable cell rate.
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.It bytes 11...13
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The maximum burst size.
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.El
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.Pp
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The variable part for ABR connections must be 19 bytes long and specifies the
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following values:
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.Bl -tag -width "bytes 12...12" -offset indent
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.It bytes 5...7
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Specifies the peak cell rate for ABR.
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.It bytes 8...10
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The minimum cell rate.
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.It bytes 11...13
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The initial cell rate.
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.It bytes 14...16
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The transient buffer exposure.
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.It byte 17
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The NRM value.
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.It byte 18
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The TRM value.
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.It bytes 19...20
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The ADTF value.
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.It byte 21
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The rate increase factor (RIF).
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.It byte 22
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The rate decrease factor (RDF).
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.It byte 23
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The cutoff decrease factor (CDF).
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.El
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.Pp
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To add a PVC the
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.Dq route
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utility can be used:
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.Pp
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.Ic # route add -iface
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.Ar <remote IP address>
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.Ic -link
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.Ar <iface> Ns Ic \&: Ns Ar <lladdr>
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.Pp
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The
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.Ar <iface>
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is the ATM interface through which
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.Ar <remote IP address>
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can be reached and
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.Ar <lladdr>
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is the link layer address as a string of dot-separated, hexadecimal bytes.
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.Pp
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NATM also supports the old, original format.
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This consists of 4 byte
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link layer addresses (and the channels are implicit UBR):
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.Bl -tag -width "bytes 12...12" -offset indent
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.It byte 0
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Flags:
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.Bl -tag -width "0x02" -offset indent -compact
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.It 0x01
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use AAL5.
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.It 0x02
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if using AAL5, use an LLC/SNAP header.
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.El
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.Pp
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Thus, parameter 3 means AAL5 and LLC/SNAP encapsulation (this is the required
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setting for interworking with other CLIP clients).
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Note that BPF works only with LLC/SNAP encapsulation.
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.It byte 1
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VPI for the channel
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.It bytes 2...3
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VCI for the channel
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.El
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.Sh EXAMPLES
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Suppose you have 3 hosts 128.252.200.1, 128.252.200.2 and
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128.252.200.3 connected by ATM through PVCs:
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.Pp
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.Bl -item -offset indent -compact
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.It
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between 128.252.200.1 and 128.252.200.2: 0xc9 UBR
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.It
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between 128.252.200.1 and 128.252.200.3: 0xca VBR
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.It
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between 128.252.200.2 and 128.252.200.3: 0xcb CBR
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.El
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.Pp
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The parameters for the VBR channel are: PCR 50000, SCR 10000, MBS 10.
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The peak cell rate for the CBR channel is 100000.
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.Pp
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To enable the links use the following commands:
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.Pp
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on host 128.252.200.1:
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.Bd -literal -offset indent -compact
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# ifconfig en0 128.252.200.1 netmask 0xffffff00 up
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# route add -iface 128.252.200.2 -link en0:3.0.0.c9.0
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# route add -iface 128.252.200.3 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a
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.Ed
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.Pp
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on host 128.252.200.2:
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.Bd -literal -offset indent -compact
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# ifconfig en0 128.252.200.2 netmask 0xffffff00 up
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# route add -iface 128.252.200.1 -link en0:3.0.0.c9.0
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# route add -iface 128.252.200.3 -link en0:3.0.0.cb.1.1.86.a0
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.Ed
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.Pp
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on host 128.252.200.3:
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.Bd -literal -offset indent -compact
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# ifconfig en0 128.252.200.3 netmask 0xffffff00 up
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# route add -iface 128.252.200.1 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a
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# route add -iface 128.252.200.2 -link en0:3.0.0.cb.1.1.86.a0
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.Ed
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.Pp
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This can also be done in
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.Xr rc.conf 5 :
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.Pp
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on host 128.252.200.1:
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.Bd -literal -offset indent -compact
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network_interfaces="lo0 en0"
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ifconfig_en0="inet 128.252.200.1 netmask 255.255.255.0"
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static_routes="host2 host3"
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route_host2="-iface 128.252.200.2 -link en0:3.0.0.c9.0"
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route_host3="-iface 128.252.200.3 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a"
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.Ed
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.Pp
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on host 128.252.200.2:
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.Bd -literal -offset indent -compact
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network_interfaces="lo0 en0"
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ifconfig_en0="inet 128.252.200.2 netmask 255.255.255.0"
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static_routes="host1 host3"
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route_host1="-iface 128.252.200.1 -link en0:3.0.0.c9.0"
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route_host3="-iface 128.252.200.3 -link en0:3.0.0.cb.1.1.86.a0"
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.Ed
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.Pp
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on host 128.252.200.3:
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.Bd -literal -offset indent -compact
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network_interfaces="lo0 en0"
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ifconfig_en0="inet 128.252.200.3 netmask 255.255.255.0"
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static_routes="host1 host2"
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route_host1="-iface 128.252.200.1 -link en0:3.0.0.ca.3.0.c3.50.0.27.10.0.0.a"
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route_host2="-iface 128.252.200.2 -link en0:3.0.0.cb.1.1.86.a0"
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.Ed
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.Sh SEE ALSO
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.Xr en 4 ,
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.Xr fatm 4 ,
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.Xr hatm 4 ,
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.Xr natm 4 ,
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.Xr patm 4
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.Sh AUTHORS
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.An Chuck Cranor
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of Washington University implemented the NATM protocol layer
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along with the EN ATM driver in 1996 for
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.Nx .
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