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-separated, 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 encapsulation (this is the required setting for interworking with other CLIP clients). Note that BPF works only with LLC/SNAP encapsulation.
