RFC relevance of transport

As per Relevance of the word transport, we have this rfc below:

Network Working Group K.
Request for Comments: 1963 S.
Category: Informational ADTRAN, Inc
August 1996

PPP Serial Data Transport Protocol (SDTP

Status of This

This memo provides information for the Internet community. This
does not specify an Internet standard of any kind. Distribution
this memo is unlimited

The Point-to-Point Protocol (PPP) [1] provides a standard method
transporting multi-protocol datagrams over point-to-point links.
defines an extensible Link Control Protocol, and proposes a family
Network Control Protocols for establishing and configuring
network-layer protocols

This document describes a new Network level protocol (from the
point of view), PPP Serial Data Transport Protocol, that
encapsulation and an associated control protocol for
serial data streams over a PPP link. This protocol was developed
the purpose of using PPP's many features to provide a standard
for synchronous data compression. The encapsulation uses a
structure based on that of the ITU-T Recommendation V.120 [2].

Table of

1. Introduction .......................................... 2
2. SDTP Packets .......................................... 3
2.1 Padding ......................................... 4
2.2 Packet Formats .................................. 4
3. Serial Data Control Protocol .......................... 11
4. SDCP Configuration Option Format ...................... 12
4.1 Packet-Format ................................... 13
4.2 Header-Type ..................................... 13
4.3 Length-Field-Present ............................ 14
4.4 Multi-Port ...................................... 14
4.5 Transport-Mode .................................. 15
4.6 Maximum-Frame-Size .............................. 16
4.7 Allow-Odd-Frames ................................ 16
4.8 FCS-Type ........................................ 17
4.9 Flow-Expiration-Time ............................ 18
SECURITY CONSIDERATIONS ...................................... 19

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RFC 1963 PPP SDTP August 1996

REFERENCES ................................................... 19
CHAIR'S ADDRESS .............................................. 20
AUTHORS' ADDRESSES ........................................... 20

1.

This document is a product of the TR30.1 ad hoc committee
compression of synchronous data. It represents a component of
proposal to use PPP to provide compression of synchronous data
DSU/CSUs

In addition to providing support for multi-protocol datagrams,
Point-to-Point Protocol (PPP) [1] has defined an effective and
negotiating mechanism that can be used on point to point links.
used in conjunction with the PPP Compression Control Protocol [3]
one of the PPP Compression Protocols [4-10], PPP provides
interoperable method of employing data compression on a point-to
point link

This document provides a PPP encapsulation for serial data
specifying a transport protocol, PPP Serial Data Transport
(PPP-SDTP), and an associated control protocol, PPP Serial
Control Protocol (PPP-SDCP). When these protocols are added to
mentioned PPP protocols, PPP can be used to provide compression
serial data on a point-to-point link

This first edition of PPP-SDTP/SDCP covers HDLC-like
serial data and asynchronous serial data. It does this by using
terminal adaption header based on that of ITU-T Recommendation V.120
[2]. Support may be added in the future for other
protocols as the marketplace demands

The V.120 terminal adaption header allows transported data frames
be split over several packets, supports the transport of DTE
idle and error information, and optionally supports the transport
DTE control state information

In addition to the V.120 Header, fields can be added to the
format through negotiation to provide support for features
included in the V.120 header. The extra fields are: a Length Field
which is used to distinguish packets in compound frames, and a
field, which is used to provide multi-port multiplexing capability
The protocol also allows reserved bits in the V.120 header to be
to transport non-octet aligned frames and to provide a flow
mechanism

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RFC 1963 PPP SDTP August 1996

To provide these features, PPP-SDTP permits a single frame format
be selected from several possible formats by using PPP-
negotiation. The terminal adaption header can be either fixed
or variable length, to allow either simplicity or flexibility

The default frame format places the terminal adaption header at
end of the packet. This permits optimal transmitter timelines
user frames are segmented and compression is also used in
with this protocol

2. SDTP

Before any SDTP packets may be communicated, PPP must reach
Network-Layer Protocol phase, and the SDTP Control Protocol
reach the Opened state

By default, exactly one SDTP packet is encapsulated in the
Information field, where the PPP Protocol field indicates type
0049 (PPP-SDTP). If the Length-Field-Present Configuration
and the LCP Compound-Frames Configuration Option are
negotiated, multiple SDTP packets may be placed in the
Information field, and they are distinguished by the presence
Length fields in each packet

The maximum length of the SDTP datagram transmitted over a PPP
is limited only by the negotiated Maximum-Frame-Size and the
length of the Information field of a PPP encapsulated packet.
that if compression is used on the PPP link, this the maximum
of the SDTP datagram may be larger or smaller than the
length of the Information field of a PPP encapsulated packet
depending on the particular compression algorithm and protocol used

ITU-T Recommendation V.120 [2] defines an adaption header that
used with its asynchronous and synchronous modes of operation.
packets include this header as a Header field to provide the
adaption function. Using negotiation, additional fields can be
to the packet to provide sequencing and multiplexing
within SDTP. SDTP also has an option of using the reserved bits
the header to provide a flow control mechanism and support
transporting non-octet aligned data frames

The default SDTP packet format is designed to allow the efficient
of the protocol's segmentation feature when combined with a
Compression Protocol [4-10]. This format is a little different
other PPP NCP's in that data is read from both ends of the packet
The Header field is placed at the end of the SDTP packet, with
order of the octets reversed. This somewhat unique format has
selected to allow optimal transmitter timelines when compression

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used and transported data frames are split into multiple
packets. In such a situation, the Header field contains
information about whether the data is split into multiple packets
not, so if it is located at the end of a packet, the decision can
made after observing the compressed size of the packet. The
field can then simply be run through the compressor after
decision has been made

When the Header field is placed before the data, as in the
packet format, the transmitter must make the decision about
to split a frame over multiple packets without knowing about
compressibility of the frame. Therefore the optional format
designed to be used when transported frames are not split
multiple SDTP packets or where SDTP is not coupled with compression
It is believed that this format may be useful for some
implementations

2.1.

If padding is used, SDTP packets require the use of the Length
or the previous negotiation of the LCP Self-Describing-
Configuration Option [11].

2.2. Packet

The default SDTP packet format is shown below. The fields
transmitted from left to right

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PPP Protocol ID | Transported Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Header - H |
+-+-+-+-+-+-+-+-+

The two complete frame formats are shown below: Header-Last
Header-First. Header-Last is the default packet format.
additional fields provided support for: Control State
(CS), multiple packets and multi-port multiplexing. Again,
fields are transmitted from left to right. Descriptions of
fields follow the packet formats

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RFC 1963 PPP SDTP August 1996

Header-

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PPP Protocol ID | (Length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Port) | Transported Data / (Odd-Pad) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Header - (CS) : H |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Header-

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PPP Protocol ID | (Length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Port) | Header - H : (CS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transported Data / (Odd-Pad) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

PPP Protocol

The PPP Protocol ID field is described in the Point-to-
Protocol Encapsulation [1].

When the SDTP Protocol is successfully negotiated by the
Control Protocol (SDCP), the value is 0049 hex. This value may
compressed to one octet when Protocol-Field-Compression
negotiated, or if one of the PPP compression protocols [4-10]
used

The optional Length field is present in every SDTP packet
successful negotiation of the Length-Field-Present
Option

The value of the Length field is the combined lengths of
Length, Port (if present), Header, Transmitted Data, and Odd-
(if present) fields in octets

The length of the Length field defaults to one octet.
lengths are from 2 to 255 octets, since each packet must

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at least a one octet Header field

If desired, the length field can be negotiated to be two octets
length. In that case, valid lengths are from 2 to 65535 octets
and the field is transmitted most significant octet first

In either case, a length of 0 means that the combined length
the same as the length of the remainder of the PPP
Field

The optional Port field is present in every SDTP packet
successful negotiation of the Multi-Port Option

The length of the Port field is one octet. Valid Port numbers
0 to 254. Port number 255 is reserved for control purposes (
section on flow control).

The Header field is the terminal adaption header from ITU-
Recommendation V.120. As specified in that document, it
up to two octets: The terminal adaption header octet (H), and
optional header extension for control state information (CS).
SDTP only supports the protocol sensitive operation of V.120;
transparent operation is not supported. The descriptions of
header bits provided below are derived from the
provided in Recommendation V.120. In addition to the
definitions of V.120, SDTP optionally permits the use of
bits to be used for flow control and to provide support for non
octet aligned frames

The length of the Header field is either one or two octets, and
determined by the value of the E bit in the first octet.
default, the E-bit must be set in the H octet and the CS octet
not present. A Configuration Option may be negotiated to
the use of the CS octet, or even to require its presence in
packet

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H (V.120 Terminal Adaption Header

The format of the first octet of the Header field is
below

0 1 2 3 4 5 6 7
+-----+-----+-----+-----+-----+-----+-----+-----+
| E | BR | Res | FC | C2 | C1 | B | F |
+-----+-----+-----+-----+-----+-----+-----+-----+

E - Extension

The E bit is the extension bit. If set to 0, it
that the Control-2 field is present

BR - Break / HDLC Idle

In asynchronous mode, the BR bit indicates the invocation
the BREAK function by the DTE. A value of 1
BREAK

In synchronous HDLC mode, the BR bit is used to
that DTE port is receiving HDLC idle condition. A value
1 indicates this idle condition

Res -

This bit is reserved and MUST be set to 0. (This is
reserved bit in V.120.)

FC - Flow

This bit can be used for flow control of SDTP traffic on
network, for applications which require it. When SDTP
used in conjunction with data compression, flow control
be needed. Reasons for this could be that the DTE port
an X.21 interface (and therefore does not have
control of DTE transmit and receive clocks), or simply
the underlying link layer (such as PPP in HDLC-like Framing
does not include a mechanism for network flow control,
some flow control mechanism is needed

This bit set to a value of 0 indicates that the receiver
ready to receive data (Flow-On). A value of 1 indicates
the receiver does not wish to receive data and
transmitting peer should stop sending it (Flow-Off).

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control operates on a per port basis. Flow control
on Port 255 affect all ports

To ensure that a missed Flow-On message cannot cause
hangup condition, a Flow-Off is defined to expire after
time of T1 seconds. If a unit desires to keep its peer
the Flow-Off state for more than T1 seconds, it
transmit another Flow-Off message after every period of T
seconds. A unit that receives a Flow-Off message may
transmitting T1 seconds after the last Flow-Off
received. The value of T1 is controlled by the Flow
Expiration-Time Configuration Option. The default value
10 seconds. There is not a separate value for T1 for
port; all ports use the same T1 value

(This bit is a reserved bit in V.120, which requires the
to be set to a value of zero. The above definition of
control provides compatibility with this definition
flow control is not used.)

C1, C2 - Error Control

The C1 and C2 bits are used for DTE port Error detection
transmission. Their meaning is defined in the
table

+----+----+--------------+--------------+
| | Meaning |
+----+----+--------------+--------------+
| C1 | C2 | Synchronous | Asynchronous |
+----+----+--------------+--------------+
| 0 | 0 | No Error | No Error |
| | | Detected | Detected |
+----+----+--------------+--------------+
| 0 | 1 | FCS Error | Stop-bit |
| | | (DTE) | Error |
+----+----+--------------+--------------+
| 1 | 0 | Abort | Parity Error |
| | | | on the Last |
| | | | Character in |
| | | | Frame |
+----+----+--------------+--------------+
| 1 | 1 | DTE Overrun* | Stop-bit and |
| | | | Parity Error |
+----+----+--------------+--------------+

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Appropriate responses to these bits are provided in
2.2.1 and 2.2.2 of the V.120 standard (where R
point is translated to mean DTE port.)

B, F - Segmentation

The B and F bits are used for segmenting and reassembly
the transported frames in synchronous HDLC mode.
the B bit to 1 indicates that the packet contains
beginning of a transported frame or a Begin Frame.
the F bit indicates that the packet contains the
portion of a transported frame, or a Final Frame. A
that contains neither the beginning of a frame nor the
is said to contain a Middle Frame. For asynchronous
and bit transparent mode operation both bits MUST be set
1. The following table summarizes the use of these bits

+---+---+--------------+----------------+
| | Application |
+---+---+--------------+----------------+
| B | F | Synchronous | Asynchronous |
+---+---+--------------+----------------+
| 1 | 0 | Begin Frame | Not Applicable |
+---+---+--------------+----------------+
| 0 | 0 | Middle Frame | Not Applicable |
+---+---+--------------+----------------+
| 1 | 0 | Final Frame | Not Applicable |
+---+---+--------------+----------------+
| 1 | 1 | Single Frame | Required |
+---+---+--------------+----------------+

CS (V.120 optional Header Extension for Control State Information

The format of the second Header octet (CS) is shown below
0 1 2 3 4 5 6 7
+-----+-----+-----+-----+-----+-----+-----+-----+
| E | DR | SR | RR | Res |(Odd-Pad Length) |
+-----+-----+-----+-----+-----+-----+-----+-----+

E - Extension

The E bit is the extension bit, and allows further
of the Header field. It is set to 1, to indicate no
extension of the Header field

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DR - Data

This bit set to 1 indicates that the DTE port is activated

SR - Send

This bit set to 1 indicates that the DTE is ready to
data

RR - Receive

This bit set to 1 indicates that the DTE is ready to
data. It can be used for DTE flow control in half-
transmissions

Res -

This bit is reserved and set to 0. (This is a V.120
bit.)

Odd-Pad Length (Optional

The Odd-Pad Length field is used when non-octet aligned
frames are allowed. It is a 3-bit field, that can take
the values of 0 through 7. Its value is the length of
Odd-Pad field in bits. This value is determined as
number of bits necessary to have the combined length of
Transported Data Field and the Odd-Pad Field be aligned
an octet boundary

If non-octet aligned frames are not allowed, this field
not used and all bits are set to the value of 0. (
bits are reserved in V.120.)

Transported

The transported data field contains the transported serial data

When the serial data type has been negotiated to be HDLC-
synchronous, this field will contain all or part of a
HDLC-like frame

A sample transported HDLC frame is shown below. The figure
not show bits inserted for transparency

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RFC 1963 PPP SDTP August 1996

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flag:01111110 | (Address, Control and Information Fields) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (FCS) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- - - - - - - - - - - - - - - -+
| Flag:01111110 |
+-+-+-+-+-+-+-+-+

Only the data between the flags is transported. The flags are
transported. The FCS is tranported unless the FCS-
Configuration Option has been successfully negotiated otherwise

Odd-

The optional Odd-Pad (Odd Frame Pad) field is used when
transported data frame is non-octet aligned, and the Allow-Odd
Frames Option has been successfully negotiated. It contains
bits that are required to pad the Transported Data field out to
octet boundary. The Odd-Pad field is in the high order bits
the last octet of the Transported Data field. The values of
bits are all zero

3. Serial Data Control

The Serial Data Control Protocol (SDCP) is responsible
configuring, enabling and disabling the SDTP modules on both ends
the point-to-point link. SDCP uses the same packet
mechanism and state machine as the Link Control Protocol.
packets may not be exchanged until PPP has reached the Network-
Protocol phase. SDCP packets received before this phase is
SHOULD be silently discarded

The Serial Data Control Protocol is exactly the same as the
Control Protocol [1] with the following exceptions

Frame

The packet may utilize any modifications to the basic frame
which have been negotiated during the Link Establishment phase

Data Link Layer Protocol

Exactly one SDCP packet is encapsulated in the PPP
field, where the PPP Protocol field indicates type hex 8049 (PPP
SDCP).

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Code

Only Codes 1 through 7 (Configure-Request, Configure-Ack
Configure-Nak, Configure-Reject, Terminate-Request, Terminate-Ack
and Code-Reject) are used. other Codes SHOULD be treated
unrecognized and SHOULD result in Code-Rejects

SDCP packets may not be exchanged until PPP has reached
Network-Layer Protocol phase. An implementation SHOULD
prepared to wait for Authentication and Link Quality
to finish before timing out waiting for a Configure-Ack or
response. It is suggested that an implementation give up
after user intervention or a configurable amount of time

Configuration Option

SDCP has a distinct set of Configuration Options which are
in this document

4. SDCP Configuration Option

SDCP Configuration Options allow modifications to the default
characteristics to be negotiated. If a Configuration Option is
included in a Configure-Request packet, the default value for
Configuration Option is assumed

SDCP uses the same Configuration Option format defined in LCP [1],
with a separate set of Options

The Option Types are

1 Packet-
2 Header-
3 Length-Field-
4 Multi-
5 Transport-
6 Maximum-Frame-
7 Allow-Odd-
8 FCS-
9 Flow-Expiration-

Note that Option Types 5-8 are specific to a single port and
port numbers in their format. Option Types 6-8 are specific to
HDLC-Synchronous Transport-Mode

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4.1. Packet-

This option selects whether the Header field precedes or follows
data field. When the Header field follows the data field, the
of its octets are reversed

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Format |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

1

3

0 Header-Last (default
1 Header-

4.2. Header-

This option selects the type of the Header field. The Header-Type
H-and-CS means that the CS octet will be present if indicated by
E-bit in the H-octet. The Header-Type of H-and-CS-Always
that both the H and CS octets are present in every packet

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Header-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

2

3

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Header-

0 H-Only (default
1 H-and-
2 H-and-CS-

4.3. Length-Field-

By default, a PPP Information Field contains only a single
packet, and an SDTP Packet does not contain a length field
Successful negotiation of this option causes all SDTP packets
contain the length field, and allows SDTP packets to be contained
compound frames (see LCP Compound-Frames Configuration Option [11]).

This option is required if the LCP Length-Field-Present
option has been negotiated

The size of the Length field is negotiated via the Length-
parameter

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Length-Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3

3

Length-

0 No Length Field (default
1 Length field of 1
2 Length field of 2

4.4. Multi-

By default, packets do not contain a port number and all packets
sent to the default port, Port 0. The Successful negotiation of
Multi-Port configuration option means that every packet will
a port number. The maximum port number, and hence the number
ports, is negotiated by using the Max-Port-Num field. A value of 0
specifies that a single port is to be used and no port field will

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RFC 1963 PPP SDTP August 1996

present in an SDTP packet. (This is the same as not negotiating
rejecting this option.) Port numbers begin with 0 and range to 254.
Port number 255 is reserved for control purposes (see section on
control).

Protocol Specific negotiations which are on a per port basis,
the port number to be specified as part of the
negotiation

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Max-Port-Num |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4

3

Max-Port-

The maximum port number that can be used. The number of
present is Max-Port-Num + 1. The value can range from 0 to 254.

4.5. Transport-

This parameter selects the mode of transport for the specified port

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Port | Mode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5

4

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RFC 1963 PPP SDTP August 1996

The port for which this option applies

The transport mode to be used for this port

0 HDLC Synchronous (default
1

4.6. Maximum-Frame-

This parameter specifies the maximum number of octets allowed in
transported data frame

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum-Frame-Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

6

7

The port for which this option applies

Maximum-Frame-

The maximum allowed length of a transported data frame in octets
Default is 10,000. Negotiable range is 1 to 2**31 - 1. The
0 is reserved to mean no limit. This field is transmitted
significant octet first

4.7. Allow-Odd-

By default, only octet-aligned data frames are allowed for transport
Successful negotiation of this option allows the transport of non
octet aligned frames. The size of the padding required to align

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frames is carried in the CS Header octet

Use of Header-Type H-Only is not permitted in conjunction with
option

0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

7

3

The port for which this option applies

4.8. FCS-

By default, the transported data frame FCS is transported.
option allows the FCS to be removed by the transmitter
regenerated by the receiver

It is important that implementations not use regeneration unless
are using PPP Reliable Transmission [12] or operating over some
layer that will provide reliable notification of a dropped packet
Implementations are not permitted to send a incomplete or bad
to the user with a good (regenerated) FCS

This option also selects the type of user FCS that will
regenerated

0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Port | FCS-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

8

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4

The port for which this option applies

FCS-

0 Transparent-Transport (Default
1 16-bit ITU-T
2 32-bit ITU-T

4.9. Flow-Expiration-

As described in section 2.2, Flow-Off messages expire after T
seconds. By default, T1 is 10 seconds. This configuration
allows the value of T1 to be changed

0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flow-Expiration-Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

9

5

Flow-Expiration-

The Flow-Expiration-Time field contains a 16 bit unsigned
which is used to specify the value to be assigned to T1
follows: T1 = Flow-Expiration-Time / 10 seconds. Therefore
value is in units of 1/10 of a second, with allowable values
1 to 2^16-1 (0.1 to 6553.5 seconds). It is transmitted
significant octet first. The default value is 100 (10 seconds),
which all must support

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RFC 1963 PPP SDTP August 1996

Security

Security issues are not discussed in this memo

[1] Simpson, W., ed., "The Point-to-Point Protocol (PPP)",
51, RFC 1661, July 1994.

[2] CCITT Recommendation V.120 (09/92), "Support by an ISDN
Data Terminal Equipment with V-Series Type Interfaces
Provision for Statistical Multiplexing", 1993.

[3] Rand, D., "The PPP Compression Control Protocol (CCP)",
1962, June 1996.

[4] Friend, R., and W. Simpson, "PPP Stac LZS
Protocol", RFC 1974, August 1996.

[5] Rand, D., "PPP Predictor Compression Protocol", RFC 1978,
August 1996.

[6] Petty, J., "PPP Hewlett-Packard Packet-by-Packet
(HP PPC) Protocol", Work in Progress

[7] Carr, D., "PPP Gandalf FZA Compression Protocol", Work
Progress

[8] Schryver, V., "PPP BSD Compression Protocol", RFC 1977,
August 1996.

[9] Schremp, et. al., "PPP Magnalink Variable
Compression", RFC 1975, August 1996.

[10] Schneider, K., "PPP Stacker LZS Compression Protocol using
DCP Header (LZS-DCP)", RFC 1967, August 1996.

[11] Simpson, W.A., "PPP LCP Extensions", RFC 1570, January 1994.

[12] Rand, D., "PPP Reliable Transmission", RFC 1663, July 1994.

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RFC 1963 PPP SDTP August 1996

Chair's

The working group can be contacted via the current chair

Karl
Ascend
3518 Riverside Drive, Suite 101
Columbus, Ohio 43221

EMail: karl@ascend.

Authors'

Questions about this memo should be directed to

Kevin
Adtran, Inc
901 Explorer Blvd
Huntsville, AL 35806-2807

Phone: (205) 971-8000
EMail: kevin@adtran.

Stuart
Adtran, Inc
901 Explorer Blvd
Huntsville, AL 35806-2807

Phone: (205) 971-8000
EMail: sventers@adtran.

Schneider & Venters Informational [Page 20]

if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.

RFC documents can be found at I.E.T.F.

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