Panasonic UF-E1, Service Manual

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UF-E1
158
From 0xxx to 3xxx of the hexadecimal number are the values of the protocol of network layer, from
8xxx to Bxxx are values of network control protocol (NCP), and xxx to Exxx are values for control
protocol of data link layer including the LCP. Of these values, the lowest bit of the upper bytes must
be 0 and the lowest bit of the lower bytes must be 1. (The upper byte is an even number and lower
byte is an odd number.) Special protocol values are listed in Table 6.5.2.3.
The latest information on the field of the PPP frames can be found in the following URL.
http://www.jana.org
(Note 1): Address/Control are constant values and can be omitted. (Refer to sections on Address/
Control field compression and ACFC option.
(Note 2): Part of the protocol can be designated by 1 byte. (Refer to sections on Protocol Field Com-
pression and PFC option.)
(Note 3): Bit value = 00000011, Order from higher bit (left) to lower bit (right) by internet expres-
sion(IANA). Note that order is inverse of the lower bit to higher bit of the Network Bit Order
(transmission to network) of IEEE/ISO/ITU. The byte expression is from higher byte to
lower byte for both internet and IEEE/ISO/ITU-T.
(Note 4): MRU: Maximum Receive Unit. Default is 1500 byte. Negotiation is possible.
Figure 6.5.2.2 PPP data link frame structure
Flag (1 byte) Flag sequence. Indicated the start/stop of frame. Value = 7Eh. In the
continuous frames, the stop flag / start flag are set one each.
Address (1 byte) (Note 1) Address, Value=FFh (all)
Control (1 byte) (Note 1) Value 0.3h (Note 3) UI (Unnumbered Information) Command, P/F bid 0
Protocol (1/2 byte) (Note 2) Protocol identification value of frame. Refer to Table 6.5.2.2.
Data Datagram of the protocol. Maximum length of data and padding = MRU
(Note 4)
PAD Appropriate padding character. Setting is arbitrary (Protocols set and
remove padding.)
FCS (2/4) Frame verification sequence from address to padding, CRC-16
(default), CRC 32
Key Point
PPP frame is HDLC compatible format
1 2
Address Control Field can be omitted
Flag
7Eh
(1)
ISO 3300 (HDLC Frame) compatible format Unit for ( ): Byte
Address
FFh
(1)
Control
03h
(1)
Protocol
(1/2)
Data PAD FCS
CRC-16/32
(2/4)
Flag
7Eh
(1)
(0 - MRU)