Network Working Group W. Simpson, Editor
Request for Comments: 1662 Daydreamer
征求意见： 1662 空想家
STD: 51 July 1994
Obsoletes: 1549
废弃、过期：1549
Category: Standards Track
分类：
PPP in HDLC-like Framing
Status of this Memo
备忘录状态
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
该文件指定一个Internet标准跟踪议定书
互联网社区，并要求讨论和建议
改进。请参阅最新出版的“互联网
官方协议标准“ （性病1 ）国家标准化
和地位的本议定书。分布的这份备忘录是无限的。
Abstract
摘要
The Point-to-Point Protocol (PPP) [1] provides a standard method for
transporting multi-protocol datagrams over point-to-point links.
在点对点协议（ PPP ） [ 1 ]提供了一个标准的方法
运送多协议数据报的点对点链接。
This document describes the use of HDLC-like framing for PPP
encapsulated packets.
本文件介绍了利用 HDLC-like framing for PPP
封装的数据包。
Table of Contents
目录
1 。导言.......................................... 1
1.1规范的要求................... 2
1.2术语..................................... 2
2 。物理层要求........................... 3
3 。在数据链路层................................... 4
3.1帧格式.................................... 5
3.2改性的基本框架................. 7
4 。字节，填充帧................................. 8
4.1检举序列................................... 8
4.2透明度.................................... 8
4.3无效帧.................................. 9
4.4时间填写....................................... 9
4.4.1字节同步............................... 9
4.4.2异步.................................... 9
4.5传输思考..................... 10
4.5.1字节同步............................... 10
4.5.2异步.................................... 10
5 。比特填充帧................................... 11
5.1检举序列................................... 11
5.2透明度.................................... 11
5.3无效帧.................................. 11
5.4时间填写....................................... 11
5.5传输思考..................... 12
6 。异步同步转换................ 13
7 。额外的LCP配置选项.................. 14
7.1异步控制字符映射（ ACCM ） .............. 14
附录................................................. .. 17
A.建议液晶选项............................... 17
湾自动识别的PPP帧................... 17
角快速帧校验序列（ FCS ）的执行情况........ 18
C.1节帧检验序列表发电机............................. 18
C.2节16位FCS的计算方法................... 19
C.3节32位FCS的计算方法................... 21
保安考虑事项...................................... 24
参考................................................. .. 24
致谢............................................. 25
主席的地址.............................................. 25
编辑地址............................................. 25
1. Introduction
1 。导言
This specification provides for framing over both bit-oriented and
octet-oriented synchronous links, and asynchronous links with 8 bits
of data and no parity. These links MUST be full-duplex, but MAY be
either dedicated or circuit-switched.
本规范规定，制定了这两个位为导向，
字节为导向的同步链接，并异步与8位
数据和没有平等。这些联系必须是全双工，但可能会
要么专门或电路交换。
An escape mechanism is specified to allow control data such as
XON/XOFF to be transmitted transparently over the link, and to remove
spurious control data which may be injected into the link by
intervening hardware and software.
逃跑的机制，允许指定的控制数据，如
XON / XOFF转交透明的链接，并删除
虚假数据控制可注入链接
干预的硬件和软件。
Some protocols expect error free transmission, and either provide
error detection only on a conditional basis, or do not provide it at
all. PPP uses the HDLC Frame Check Sequence for error detection.
This is commonly available in hardware implementations, and a
software implementation is provided.
有些协议预计无差错传输，并可以提供
错误检测只能在有条件的基础上，或不提供在
全部。使用购买力平价的HDLC帧校验序列的错误检测。
这是常见的硬件实现，并
软件实施提供。
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RFC 1662 HDLC-like Framing July 1994
1.1. Specification of Requirements
1.1 。规格要求
In this document, several words are used to signify the requirements
of the specification. These words are often capitalized.
在本文件中，有几个关键词是用来标志要求
的规范。这些话往往是大写。
MUST This word, or the adjective "required", means that the
definition is an absolute requirement of the specification.
必须这个字，或形容词“需要” ，这意味着
定义是一个绝对的要求，规范。
MUST NOT This phrase means that the definition is an absolute
prohibition of the specification.
不可以这句话意味着，定义是一个绝对的
禁止规范。
SHOULD This word, or the adjective "recommended", means that there
may exist valid reasons in particular circumstances to
ignore this item, but the full implications must be
understood and carefully weighed before choosing a
different course.
应该 这个词，或形容词“建议” ，这意味着
可能存在的正当理由在特殊情况下，以
忽略这个项目，但必须是全面的影响
理解和认真权衡，然后再选择
不同的课程。
MAY This word, or the adjective "optional", means that this
item is one of an allowed set of alternatives. An
implementation which does not include this option MUST be
prepared to interoperate with another implementation which
does include the option.
可以 这个词或形容词“可选的” ，是指该
项目是允许的一套办法。一个
执行其中不包括此选项必须是
互准备与另一执行的
不包括选项。
1.2. Terminology
1.2 。术语
This document frequently uses the following terms:
本文件经常使用的下列术语：
datagram The unit of transmission in the network layer (such as IP).
A datagram may be encapsulated in one or more packets
passed to the data link layer.
数据包 数据传输的单位中的网络层（如IP ） 。
阿数据可以封装在一个或多个包
传递给数据链路层。
frame The unit of transmission at the data link layer. A frame
may include a header and/or a trailer, along with some
number of units of data.
帧 的单位传输的数据链路层。画框
可能包含标题和/或拖车，以及一些
一些单位的数据。
packet The basic unit of encapsulation, which is passed across the
interface between the network layer and the data link
layer. A packet is usually mapped to a frame; the
exceptions are when data link layer fragmentation is being
performed, or when multiple packets are incorporated into a
single frame.
分组 基本单位，封装，这是通过跨越
接口之间的网络层和数据链路
阶层。一包通常是映射到一个框架;的
例外的是在数据链路层正在分裂
演出时，或多个数据包纳入
单张。
、
peer The other end of the point-to-point link.
同行 另一端的点对点链接。
silently discard
The implementation discards the packet without further
processing. The implementation SHOULD provide the
capability of logging the error, including the contents of
the silently discarded packet, and SHOULD record the event
in a statistics counter.
悄悄地丢弃
执行丢弃的数据包没有进一步
处理。执行应提供
能力记录错误，包括的内容
默默丢弃的数据包，并应记录事件
在一个统计计数器。
Simpson [Page 2]
RFC 1662 HDLC-like Framing July 1994
2. Physical Layer Requirements
2 。物理层要求
PPP is capable of operating across most DTE/DCE interfaces (such as,
EIA RS-232-E, EIA RS-422, and CCITT V.35). The only absolute
requirement imposed by PPP is the provision of a full-duplex circuit,
either dedicated or circuit-switched, which can operate in either an
asynchronous (start/stop), bit-synchronous, or octet-synchronous
mode, transparent to PPP Data Link Layer frames.
PPP 是能够运行在大多数终端/的DCE接口（如，环境影响评估RS - 232接口，英，环境影响评估遥感- 422 ，和国际电报电话咨询委员会V.35 ） 。唯一的绝对施加的要求而按 PPP 是提供全双工电路，要么专门或电路交换，它可以在任何一个异步（启动/停止） ，位同步，或字节同步 模式，透明，以购买力平价数据链路层帧。
Interface Format
接口格式
PPP presents an octet interface to the physical layer. There is
no provision for sub-octets to be supplied or accepted.
PPP 介绍了八位接口的物理层。有
没有规定分八位字节，所须提供或接受。
Transmission Rate
传输速率
PPP does not impose any restrictions regarding transmission rate,
other than that of the particular DTE/DCE interface.
购买力平价没有任何限制的传输速率，
以外的特定终端/二氯乙烷界面。
Control Signals
控制信号
PPP does not require the use of control signals, such as Request
To Send (RTS), Clear To Send (CTS), Data Carrier Detect (DCD), and
Data Terminal Ready (DTR).
PPP 并不需要使用控制信号，如要求
发送（即时战略） ，清除发送（旅） ，数据载波检测（双氰胺）和
数据终端就绪（ DTR ） 。
When available, using such signals can allow greater functionality
and performance. In particular, such signals SHOULD be used to
signal the Up and Down events in the LCP Option Negotiation
Automaton [1]. When such signals are not available, the
implementation MUST signal the Up event to LCP upon
initialization, and SHOULD NOT signal the Down event.
可用时，使用这种信号可以使更多的功能
和性能。尤其是，这种信号应使用
信号向上和向下事件 在 液晶选项协商
自动机[ 1 ] 。当这样的信号是不具备，
实施必须信号向上事件后液晶
初始化，而不应信号向下事件。
Because signalling is not required, the physical layer MAY be
decoupled from the data link layer, hiding the transient details
of the physical transport. This has implications for mobility in
cellular radio networks, and other rapidly switching links.
由于信号不是必需的，在物理层可被
脱钩的数据链路层，隐藏的瞬态细节
物理交通工具。这将影响流动性
蜂窝无线网络，和其他迅速交换链接。
When moving from cell to cell within the same zone, an
implementation MAY choose to treat the entire zone as a single
link, even though transmission is switched among several
frequencies. The link is considered to be with the central
control unit for the zone, rather than the individual cell
transceivers. However, the link SHOULD re-establish its
configuration whenever the link is switched to a different
administration.
当从细胞到细胞内的同一地区，一个
实施可以选择对待整个区域作为一个单一的
链接，即使传输交换的若干
频率。该链接被认为是与中央
控制单元的区域，而不是个人细胞
收发器。然而，这个连接应该重新确立其
配置每当链接切换到一个不同的
管理。
Due to the bursty nature of data traffic, some implementations
have choosen to disconnect the physical layer during periods of
由于突发性的数据流量，一些实
选择断开物理层 从周边设备
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RFC 1662 HDLC-like Framing July 1994
inactivity, and reconnect when traffic resumes, without informing
the data link layer. Robust implementations should avoid using
this trick over-zealously, since the price for decreased setup
latency is decreased security. Implementations SHOULD signal the
Down event whenever "significant time" has elapsed since the link
was disconnected. The value for "significant time" is a matter of
considerable debate, and is based on the tariffs, call setup
times, and security concerns of the installation.
活动，并重新恢复交通时，没有通知
数据链路层。强大的执行应避免使用
这种伎俩过于热心，因为价格下降安装
潜伏期降低安全性。应实施的信号
唐氏事件时， “大量的时间”已过了链接
断开。的值为“大量的时间”是一个问题
相当多的辩论，是基于关税，呼叫设置
有时，和安全问题的关切安装。
3. The Data Link Layer
3 。在数据链路层
PPP uses the principles described in ISO 3309-1979 HDLC frame
structure, most recently the fourth edition 3309:1991 [2], which
specifies modifications to allow HDLC use in asynchronous
environments.
使用PPP 的原则中所描述的ISO 3309-1979的HDLC帧
结构，特别是最近第四版3309:1991 [ 2 ] ，其中
具体的修改，允许使用的异步链路
环境。
The PPP control procedures use the Control field encodings described
in ISO 4335-1979 HDLC elements of procedures, most recently the
fourth edition 4335:1991 [4].
在PPP控制程序使用控制领域编码描述
在ISO 4335-1979的HDLC要素程序，最近的
第四版4335:1991 [ 4 ] 。
This should not be construed to indicate that every feature of the
above recommendations are included in PPP. Each feature included
is explicitly described in the following sections.
这不应被理解为表明，每一个功能的
上述建议包含在PPP中。每个功能包括：
明确说明以下各节中。
To remain consistent with standard Internet practice, and avoid
confusion for people used to reading RFCs, all binary numbers in the
following descriptions are in Most Significant Bit to Least
Significant Bit order, reading from left to right, unless otherwise
indicated. Note that this is contrary to standard ISO and CCITT
practice which orders bits as transmitted (network bit order). Keep
this in mind when comparing this document with the international
standards documents.
为了保持符合标准互联网的做法，并避免
混乱的人用于阅读RFCs ，在所有的二进制数字
下面的说明是在最高有效位向最不
有效位秩序，阅读从左至右，除非另有
表示。请注意，这是违反标准的国际标准化组织和国际电话电报谘询委员会
这种做法订单位转交（网络位顺序） 。保持
考虑到这一点时，该文件比较与国际
标准的文件。
Simpson [Page 4]
RFC 1662 HDLC-like Framing July 1994
3.1. Frame Format
3.1 。帧格式
A summary of the PPP HDLC-like frame structure is shown below. This
figure does not include bits inserted for synchronization (such as
start and stop bits for asynchronous links), nor any bits or octets
inserted for transparency. The fields are transmitted from left to
right.
简要介绍了PPP 的HDLC样框架结构如下所示。这个
数字不包括钻头插入同步（如
启动和停止位异步链接） ，也没有任何位或八位字节
插入的透明度。传输领域从左至右
右边。
+----------+----------+----------+
| Flag | Address | Control |
| 01111110 | 11111111 | 00000011 |
+----------+----------+----------+
+----------+-------------+---------+
| Protocol | Information | Padding |
| 8/16 bits| * | * |
+----------+-------------+---------+
+----------+----------+-----------------
| FCS | Flag | Inter-frame Fill
|16/32 bits| 01111110 | or next Address
+----------+----------+-----------------
+----------+----------+----------+
| 标记 | 地址 | 控制中心 |
| 01111110 | 11111111 | 00000011 |
+----------+----------+----------+
+----------+-------------+---------+
| 协议 | 信息 | 填充 |
| 8 / 16位 | * | * |
+----------+-------------+---------+
+----------+----------+-----------------
| 现场总线 | 标记 | 帧间填写
| 16/32位 | 01111110 | 或下一地址
+----------+----------+-----------------
The Protocol, Information and Padding fields are described in the
Point-to-Point Protocol Encapsulation [1].
该协议，信息和填充领域中所描述
点对点协议封装[ 1 ] 。
Flag Sequence
标记序列
Each frame begins and ends with a Flag Sequence, which is the
binary sequence 01111110 (hexadecimal 0x7e). All implementations
continuously check for this flag, which is used for frame
synchronization.
每帧开始和结束的一个标志序列，这是
二进制序列01111110 （十六进制0x7e ） 。全部实现
不断检查这个旗标，这是用于框架
同步。
Only one Flag Sequence is required between two frames. Two
consecutive Flag Sequences constitute an empty frame, which is
silently discarded, and not counted as a FCS error.
只需要有一个标记序列在两个帧之间。二
连续检举序列构成一个空的框架，这是
悄悄地丢弃，而不是算作FCS的错误。
Address Field
地址栏
The Address field is a single octet, which contains the binary
sequence 11111111 (hexadecimal 0xff), the All-Stations address.
Individual station addresses are not assigned. The All-Stations
address MUST always be recognized and received.
地址字段是一个单一的字节，其中包含二进制
序列11111111 （十六进制0xff ） ，全站的地址。
个别车站地址不分配。全站
地址必须始终得到承认和接受。
The use of other address lengths and values may be defined at a
later time, or by prior agreement. Frames with unrecognized
Addresses SHOULD be silently discarded.
使用其他地址长度和价值可以被定义在
稍后时间，或事先约定。无法辨识
地址的帧应该是悄悄地丢弃。
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RFC 1662 HDLC-like Framing July 1994
Control Field
控制领域
The Control field is a single octet, which contains the binary
sequence 00000011 (hexadecimal 0x03), the Unnumbered Information
(UI) command with the Poll/Final (P/F) bit set to zero.
控制区域是一个单一的字节，其中包含二进制
序列00000011 （十六进制0x03 ）中，无编号信息
（ UI ）的指令与Poll/Final (P/F) 位设置为0 。
The use of other Control field values may be defined at a later
time, or by prior agreement. Frames with unrecognized Control
field values SHOULD be silently discarded.
使用其他控制字段值可能会在晚些时候确定
时间，或事先约定。张无法辨识的控制
外地价值应默默丢弃。
Frame Check Sequence (FCS) Field
帧校验序列（ FCS ）的区域
The Frame Check Sequence field defaults to 16 bits (two octets).
The FCS is transmitted least significant octet first, which
contains the coefficient of the highest term.
该帧校验序列字段默认为16位（ 2字节） 。
功能界别的是最不重要的字节转交第一，其中
载系数最高的。
A 32-bit (four octet) FCS is also defined. Its use may be
negotiated as described in "PPP LCP Extensions" [5].
32位（ 4字节）帧检验序列也是界定。它的使用可
谈判中描述的“ppp LCP扩展” [ 5 ] 。 ‘
The use of other FCS lengths may be defined at a later time, or by
prior agreement.
使用其他FCS的长度可以被定义在以后某一时间，或通过
事先约定。
The FCS field is calculated over all bits of the Address, Control,
Protocol, Information and Padding fields, not including any start
and stop bits (asynchronous) nor any bits (synchronous) or octets
(asynchronous or synchronous) inserted for transparency. This
also does not include the Flag Sequences nor the FCS field itself.
功能界别的领域是计算所有位的地址，控制，
议定书，信息和填充领域，不包括任何启动
和停止位（异步） ，也没有任何比特（同步）或八位字节
（异步或同步）插入的透明度。这个
也没有包括标记序列也不是FCS的外地本身。
When octets are received which are flagged in the Async-
Control-Character-Map, they are discarded before calculating
the FCS.
当八位组收到这些标记中的异步，
控制字符地图，他们将被丢弃在计算
在现场总线控制系统。
For more information on the specification of the FCS, see the
Appendices.
欲了解更多有关该规范的现场总线控制系统，请参阅
附录。
The end of the Information and Padding fields is found by locating
the closing Flag Sequence and removing the Frame Check Sequence
field.
年底的信息和填充字段被发现的定位
闭幕检举序列和删除帧校验序列
领域。
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RFC 1662 HDLC-like Framing July 1994
3.2. Modification of the Basic Frame
3.2 。改造的基本框架
The Link Control Protocol can negotiate modifications to the standard
HDLC-like frame structure. However, modified frames will always be
clearly distinguishable from standard frames.
链路控制协议可以谈判修改标准
HDLC-like 框架结构。然而，修改的帧将永远
清楚识别，从标准的框架。
Address-and-Control-Field-Compression
地址和控制字段压缩
When using the standard HDLC-like framing, the Address and Control
fields contain the hexadecimal values 0xff and 0x03 respectively.
When other Address or Control field values are in use, Address-
and-Control-Field-Compression MUST NOT be negotiated.
当使用标准的HDLC样框架，地址和控制
字段包含的十六进制值分别0xff和0x03 。
当其他地址或控制字段值都在使用，地址，
控制场压缩绝不能谈判。
On transmission, compressed Address and Control fields are simply
omitted.
传输，压缩地址和控制领域的根本
省略。
On reception, the Address and Control fields are decompressed by
examining the first two octets. If they contain the values 0xff
and 0x03, they are assumed to be the Address and Control fields.
If not, it is assumed that the fields were compressed and were not
transmitted.
在招待会上，地址和控制领域的解压缩的
审查前两个八位组。如果它们包含的价值观念0xff
和0x03 ，他们假定的地址和控制领域。
如果不是，它是假定领域被压缩，而不是
转交。
By definition, the first octet of a two octet Protocol field
will never be 0xff (since it is not even). The Protocol field
value 0x00ff is not allowed (reserved) to avoid ambiguity when
Protocol-Field-Compression is enabled and the first Information
field octet is 0x03.
根据定义，第一个八位组的两个八位议定书领域
将永远0xff （因为它甚至没有） 。该议定书领域
价值0x00ff是不允许的（保留） ，以避免歧义时，
议定书场压缩已启用的第一个信息
外地字节是0x03 。
Simpson [Page 7]
RFC 1662 HDLC-like Framing July 1994
4. Octet-stuffed framing
4 。字节，填充帧
This chapter summarizes the use of HDLC-like framing with 8-bit
asynchronous and octet-synchronous links.
本章概述了利用HDLC-like 制定与8位
异步和字节同步链接。
4.1. Flag Sequence
4.1 。检举序列
The Flag Sequence indicates the beginning or end of a frame. The
octet stream is examined on an octet-by-octet basis for the value
01111110 (hexadecimal 0x7e).
旗序列显示的开头或结尾的框架。那个
字节流进行审查的八位由八位基础的价值
01111110 （十六进制0x7e ） 。
4.2. Transparency
4.2 。透明度
An octet stuffing procedure is used. The Control Escape octet is
defined as binary 01111101 (hexadecimal 0x7d), most significant bit
first.
一个字节是用来填充程序。控制转义字节是
定义为二进制01111101 （十六进制0x7d ） ，最重要的位
首先。
As a minimum, sending implementations MUST escape the Flag Sequence
and Control Escape octets.
作为最低限度，必须把实现逃避检举序列
控制转义字节。
After FCS computation, the transmitter examines the entire frame
between the two Flag Sequences. Each Flag Sequence, Control Escape
octet, and any octet which is flagged in the sending Async-Control-
Character-Map (ACCM), is replaced by a two octet sequence consisting
of the Control Escape octet followed by the original octet
exclusive-or'd with hexadecimal 0x20.
在现场总线控制系统的计算，发射机审查整个画面
两国之间的检举序列。每个旗序列，控制逃逸
八位，任何八位是标示在发送异步控
字符地图（ ACCM ） ，是取代了两个字节序列组成
控制转义字节其次是原始字节
独家- or'd与十六进制0x20 。
This is bit 5 complemented, where the bit positions are numbered
76543210 (the 6th bit as used in ISO numbered 87654321 -- BEWARE
when comparing documents).
这是5位的补充，在一些职位编号
76543210 （第6位中所使用的ISO编号87654321 -提防
当比较文件）
Receiving implementations MUST correctly process all Control Escape
sequences.
接收实施必须正确处理所有控制逃逸
序列。
On reception, prior to FCS computation, each octet with value less
than hexadecimal 0x20 is checked. If it is flagged in the receiving
ACCM, it is simply removed (it may have been inserted by intervening
data communications equipment). Each Control Escape octet is also
removed, and the following octet is exclusive-or'd with hexadecimal
0x20, unless it is the Flag Sequence (which aborts a frame).
受理，现场之前计算，每个字节的值小于
比十六进制0x20检查。如果它被标记在接收
ACCM ，这只是删除（它可能已被插入的干预
数据通信设备） 。每个控制转义字节也
删除，下面的字节是独家经营权， or'd与十六进制
0x20 ，除非它是检举序列（其中中止一帧） 。
A few examples may make this more clear. Escaped data is transmitted
on the link as follows:
有几个例子可以使这种更加明确。转义数据传输
链接如下：
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RFC 1662 HDLC-like Framing July 1994
0x7e is encoded as 0x7d, 0x5e. (Flag Sequence) （旗序列）
0x7d is encoded as 0x7d, 0x5d. (Control Escape) （控制逃脱）
0x03 is encoded as 0x7d, 0x23. (ETX) （ ETX系统）
Some modems with software flow control may intercept outgoing DC1 and
DC3 ignoring the 8th (parity) bit. This data would be transmitted on
the link as follows:
有些调制解调器的软件流控制可拦截即将离任的DC1和
DC3无视第八（平价）位。这些数据将转交有关
链接如下：
0x11 is encoded as 0x7d, 0x31. (XON)
0x13 is encoded as 0x7d, 0x33. (XOFF)
0x91 is encoded as 0x7d, 0xb1. (XON with parity set)
0x93 is encoded as 0x7d, 0xb3. (XOFF with parity set)
4.3. Invalid Frames
4.3 。无效帧
Frames which are too short (less than 4 octets when using the 16-bit
FCS), or which end with a Control Escape octet followed immediately
by a closing Flag Sequence, or in which octet-framing is violated (by
transmitting a "0" stop bit where a "1" bit is expected), are
silently discarded, and not counted as a FCS error.
帧是太短（少于4字节时，使用16位
现场总线控制系统） ，或在结尾加上一个控制转义字节紧随其后
闭幕检举的序列，或在其中八位-帧是侵犯（由
转递“ 0 ”停止位在一个“ 1 ”位预计） ，是
悄悄地丢弃，而不是算作FCS的错误。
4.4. Time Fill
4.4 。时间填写
4.4.1. Octet-synchronous
4.4.1 。字节同步
There is no provision for inter-octet time fill.
没有规定间八位时间填写。
The Flag Sequence MUST be transmitted during inter-frame time fill.
旗序列必须转在帧间的时间填写。
4.4.2. Asynchronous
4.4.2 。异步
Inter-octet time fill MUST be accomplished by transmitting continuous
"1" bits (mark-hold state).
间八位时间填写必须完成的转递持续
“ 1 ”比特（商标持有国） 。
Inter-frame time fill can be viewed as extended inter-octet time
fill. Doing so can save one octet for every frame, decreasing delay
and increasing bandwidth. This is possible since a Flag Sequence may
serve as both a frame end and a frame begin. After having received
any frame, an idle receiver will always be in a frame begin state.
帧间时间填写可视为延长间八位时间
充满。这样做可以节省一个字节的每一帧，减少延误
以及增加带宽。这是可能的，因为国旗序列可能
既是一帧一帧结束和开始。在收到
任何画面，空闲接收机将永远是在一个框架开始的状态。
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RFC 1662 HDLC-like Framing July 1994
Robust transmitters should avoid using this trick over-zealously,
since the price for decreased delay is decreased reliability. Noisy
links may cause the receiver to receive garbage characters and
interpret them as part of an incoming frame. If the transmitter does
not send a new opening Flag Sequence before sending the next frame,
then that frame will be appended to the noise characters causing an
invalid frame (with high reliability).
强大的发射机应避免使用这一伎俩过度热忱，
由于价格下降延迟降低可靠性。噪声
联系可能会导致接收机接收乱码和
解释他们的一个组成部分传入帧。如果发射机不
不派一个新的开放序列，然后递交检举下一帧，
然后是内将附加到字符造成的噪音
无效帧（高可靠性） 。
It is suggested that implementations will achieve the best results by
always sending an opening Flag Sequence if the new frame is not
back-to-back with the last. Transmitters SHOULD send an open Flag
Sequence whenever "appreciable time" has elapsed after the prior
closing Flag Sequence. The maximum value for "appreciable time" is
likely to be no greater than the typing rate of a slow typist, about
1 second.
有人建议，实施将实现最好的结果
总是发送开放检举序列的新的框架，如果不是
背对背的最后。发射机应派遣一个开放的旗帜
序列时， “可观的时间”已经过去后，事先
关闭检举序列。最高值为“可观的时间”是
可能是不大于打字速度缓慢的打字员，约
一秒。
4.5. Transmission Considerations
4.5 。传输思考
4.5.1. Octet-synchronous
4.5.1 。字节同步
The definition of various encodings and scrambling is the
responsibility of the DTE/DCE equipment in use, and is outside the
scope of this specification.
各种编码及加扰的定义，是
负责终端/的DCE设备的使用，不属于
范围本规范。
4.5.2. Asynchronous
4.5.2 。异步
All octets are transmitted least significant bit first, with one
start bit, eight bits of data, and one stop bit. There is no
provision for seven bit asynchronous links.
所有字节传输最低有效位第一次，其中一人
开始位， 8位数据，一个停止位。不存在
规定7位异步联系。
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RFC 1662 HDLC-like Framing July 1994
5. Bit-stuffed framing
5 。比特填充帧
This chapter summarizes the use of HDLC-like framing with bit-
synchronous links.
本章概述了利用HDLC-like 制定与比特
同步链接。
5.1. Flag Sequence
5.1 。检举序列
The Flag Sequence indicates the beginning or end of a frame, and is
used for frame synchronization. The bit stream is examined on a
bit-by-bit basis for the binary sequence 01111110 (hexadecimal 0x7e).
旗序列显示的开头或结尾的框架，并
用于帧同步。比特流的检查
位的位基础的二进制序列01111110 （十六进制0x7e ） 。
The "shared zero mode" Flag Sequence "011111101111110" SHOULD NOT be
used. When not avoidable, such an implementation MUST ensure that
the first Flag Sequence detected (the end of the frame) is promptly
communicated to the link layer. Use of the shared zero mode hinders
interoperability with bit-synchronous to asynchronous and bit-
synchronous to octet-synchronous converters.
的“共同零模式”检举序“ 011111101111110 ”不应该
使用。当不可以避免的，这样的执行必须确保
第一旗序列检测（结束帧）是迅速
送交链路层。使用共享零模式阻碍
互操作性位同步到异步和位
同步到八位同步转换器。
5.2. Transparency
5.2 。透明度
After FCS computation, the transmitter examines the entire frame
between the two Flag Sequences. A "0" bit is inserted after all
sequences of five contiguous "1" bits (including the last 5 bits of
the FCS) to ensure that a Flag Sequence is not simulated.
在现场总线控制系统的计算，发射机审查整个画面
两国之间的检举序列。 “ 0 ”位插入毕竟
序列五个连续“ 1 ”比特（包括最后5位
在现场总线控制系统） ，以确保国旗序列不是模拟。
On reception, prior to FCS computation, any "0" bit that directly
follows five contiguous "1" bits is discarded.
受理，现场总线控制系统计算之前，任何“ 0 ”位，直接
如下五个连续的“ 1 ”位被丢弃。
5.3. Invalid Frames
5.3 。无效帧
Frames which are too short (less than 4 octets when using the 16-bit
FCS), or which end with a sequence of more than six "1" bits, are
silently discarded, and not counted as a FCS error.
帧是太短（少于4字节时，使用16位
现场总线控制系统） ，或在结尾加上一个序列超过6 “ 1 ”位，是
悄悄地丢弃，而不是算作FCS的错误。
5.4. Time Fill
5.4 。时间填写
There is no provision for inter-octet time fill.
没有规定间八位时间填写。
The Flag Sequence SHOULD be transmitted during inter-frame time fill.
However, certain types of circuit-switched links require the use of
旗序列应转交在帧间的时间填写。
然而，某些类型的电路交换链接要求使用
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RFC 1662 HDLC-like Framing July 1994
mark idle (continuous ones), particularly those that calculate
accounting based on periods of bit activity. When mark idle is used
on a bit-synchronous link, the implementation MUST ensure at least 15
consecutive "1" bits between Flags during the idle period, and that
the Flag Sequence is always generated at the beginning of a frame
after an idle period.
商标闲置（连续的） ，特别是那些计算
会计期间的基础上位活动。当闲置商标使用
对位同步链接，执行必须确保至少有15个
连续的“ 1 ”比特之间的旗帜在闲置期间，这
旗序列生成总是开始时一帧
之后的闲置期。
This differs from practice in ISO 3309, which allows 7 to 14 bit
mark idle.
这不同于做法在ISO 3309 ，从而使7至14位
商标闲置。
5.5. Transmission Considerations
5.5 。传输思考
All octets are transmitted least significant bit first.
所有字节传输最低有效位第一。
The definition of various encodings and scrambling is the
responsibility of the DTE/DCE equipment in use, and is outside the
scope of this specification.
的定义，各种编码及加扰是
负责终端/的DCE设备的使用，不属于
范围本规范。
While PPP will operate without regard to the underlying
representation of the bit stream, lack of standards for transmission
will hinder interoperability as surely as lack of data link
standards. At speeds of 56 Kbps through 2.0 Mbps, NRZ is currently
most widely available, and on that basis is recommended as a default.
虽然按购买力平价将运作方面的基本
代表性的比特流，缺乏标准的传输
将阻碍互操作性，因此必然缺乏数据链路
标准。在时速56 Kbps的2.0 Mbps的通过，目前正在NRZ码
最广泛使用，并在此基础上，建议设置为默认。
When configuration of the encoding is allowed, NRZI is recommended as
an alternative, because of its relative immunity to signal inversion
configuration errors, and instances when it MAY allow connection
without an expensive DSU/CSU. Unfortunately, NRZI encoding
exacerbates the missing x1 factor of the 16-bit FCS, so that one
error in 2**15 goes undetected (instead of one in 2**16), and triple
errors are not detected. Therefore, when NRZI is in use, it is
recommended that the 32-bit FCS be negotiated, which includes the x1
factor.
当配置的编码是允许的，建议作为NRZI
一种替代办法，因为它的相对免疫力信号反转
配置错误，和情况时，可允许连接
没有昂贵的谅解/基社盟。不幸的是， NRZI编码
加剧了失踪x1因素的16位现场总线控制系统，使一个
错误2 ** 15不知不觉中（而不是一个在2 ** 16 ） ，和三
错误是未检出。因此，当NRZI正在使用中，它是
建议， 32位现场总线控制系统进行谈判，其中包括x1
因素。
At higher speeds of up to 45 Mbps, some implementors have chosen the
ANSI High Speed Synchronous Interface [HSSI]. While this experience
is currently limited, implementors are encouraged to cooperate in
choosing transmission encoding.
在更高的速度高达45 Mbps的，有些执行者选择了
标准高速同步接口[ HSSI ] 。虽然这方面的经验
目前有限的，执行者是鼓励各国进行合作以
选择传输编码。
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RFC 1662 HDLC-like Framing July 1994
6. Asynchronous to Synchronous Conversion
6 。异步同步转换
There may be some use of asynchronous-to-synchronous converters (some
built into modems and cellular interfaces), resulting in an
asynchronous PPP implementation on one end of a link and a
synchronous implementation on