V5 protocol English

 1. Overview

 2. V5 Protocol Introduction

 3. hardware configuration

 4. data configuration

1. OVERVIEW

1). V Interface

 The digital interface between the access network

and the switch，including V1、V2、V3、V4、V5。

2). The limitation of the V1～V4 interfaces.

V1 to V4 interfaces don’t support integrated access.
And the more important is : V1 to V4 are all not standard
interfaces, which hampers the development and use of the
V interfaces.

3).THE FEATURE OF V5

the V5 interfaces are more open and standard, and it
has the ability of integrated access.

4).SERVICES SUPPORTED BY DIFFERENT V
INTERFACES
 V1 interface ISDN BRA（2B＋D） access
 V2 interface 2Mb/s、8Mb/s access
 V3 interface ISDN PRA（30B＋D） access
 V4 interface Multiple 2B＋D access
 V5 interface ISDN/PSTN integrated access

5)、COMPARISON BETWEEN V5.1 INTERFACE
AND V5.2
V5.1 interface  V5.2 interface

Support a PCM link Support 1-16 PCM links
Dynamic time slot
allocation and have the
The time slots at the user port
traffic concentration
and on the PCM link are
function
fixedly allocated, without the
traffic concentration function

V5.1 interface  V5.2 interface

Has not the function of Has the function of
protecting the communication protecting the
channels communication channels (C
channels)

2. V5 PROTOCOL
INTRODUCTION

(1)、Basic concepts

(2)、Structure

(3)、layers

1). Basic Concepts
Link: one 2048Kbit/s PCM system in the V5 interface.

Channel:one 64kb/s time slot in a link.
Including B channel and C channel.

Bearer channel (B-channel)：
the channel used to carry service

Communication channel ( C channel):
the channel used to carry signaling

logic C channel: Make up of by some protocol. Include
PSTN protocol, BCC protocol, Control protocol, Link control
protocol and protection protocol.

Physical C channel: The V5.2 interface has been allocated the
64Kbit/s time slots used to carry the logic C channel. TS16 is
always as the physical C channel.

Active physical C channel: The physical C channel
currently bearing the logic C channel.

Standby physical C channel: The physical C channel
currently bearing only the protection protocol is used as
the standby channel of the logic C channel carried on the
active physical C channel, that is, it is used to protect the
logic C channel.

 Main link :The link has active physical C channel.

 Sub-link: The link has Standby physical C channel.

Synchronization channel
Signaling channel
Bearer channel

Figure(1)：Link and Channels

TS0 TS1 TS2 TS15 TS16 TS17 TS30 TS31

TS0 TS1 TS2 TS15 TS16 TS17 TS30 TS31

Synchronization time slot
Signaling time slot
Bearer time slot

Figure：Time slots allocation of 2M links

Figure: Logic C channel and Physical C channel

2). STRUCTURE Application Layer

Data Link Layer

Physical Layer

Figure: Structure model of V5 protocol

Application Application
Layer Layer

Data Link Data Link
Layer C channel Layer

Physical Physical
Layer Layer

B channel

Figure: PSTN call procedure through V5 interface

Application Application
Layer Layer

Data Link Data Link
Layer Layer
C channel

Physical Physical
Layer Layer

B channel

Figure: ISDN call procedure through V5 interface

3)、Layer function description

A). Physical layer：
Providing physical transmission channels for all kinds of
messages.
The physical layer of the V5 interface is composed of
2048Kbit/s links.

TS 15, 16 and 31 of every 2048Kbit/s link can be used as the
physical C channel. The time slots that are not used as the
physical C channels shall be used as B-channels.

B). Data link layer:
Provide the transmission capability for Layer 3 message and the
data.
Including:LAPV5-EF（Encapsulation Function sub_layer）、
LAPV5-DL（Data link sub_layer）、AN frame relay sub_layer、
Mapping function sub_layer.

ISDN-TE

Q. PS Q.
BCC PS
Control Link Link
control
protection control
control
protection BCC
931 TN TN 931
LAPV5-DL LAPV5-DL Q.
921

Q. P Mapping Mapping
ET/L2
921 S
T LAPV5-EF
N

D16 D16
TE LC C64 C64
/64 /64

AN frame relay

Explanation
TE：Terminal Equipment
LC：Line Circuit
ET/L2：exchange terminal/Layer 2 functions
D16/64：16kbit/s or 64kbit/s D-channel
C64：64kbit/s communication channel
LAPV5-DL：The data link sub_layer of the V5 interface LAPV5-
EF：The encapsulating function sub_layer of the V5 interface

LAPV5-EF（encapsulation function sub_layer）：

Provide common encapsulation function and disassembling
function to LAPV5-DL frame.

The end-to-end information exchange of the encapsulating
functions between the AN and the LE is done in the form of
frames.

LAPV5-DL（data link sub_layer）：

Encapsulates the messages from layer 3 into LAPV5-DL
frame;Get out the messages of layer 3 from LAPV5-DL frame.

The data current in this sub_layer has the following frame
format.

Link addr(high order) byte1
Link addr(low order) byte2
Control byte3
Control byte4

Information ….

LAPV5-DL distinguishes different kinds of information
by link address. The link address consists two bytes.

AN frame relay sub_layer:
Accomplishing the frame multiplexing and multiplexing of the
ISDN user ports cooperating with the LAPV5-EF sub_layer.

LAPV5 - DL
From user port to AN:
Getting rid of the head and end labels
and check sequence from the frame and
Mapping
turn it into AN frame relay. According to
the ISDN user port,it gives the frame an
Efaddr,and then send it to mapping
AN frame
LAPV5 - EF
function sub_layer. The mapping relay

function sub_layer will map the frame to D16/64 C64

Ef sublayer in which the frame will be
encapsulated it to LAPV5-EF frame and ISDN user

sent to V5 communication channel.

C). Application layer

V5.2 includes 5 protocols.

Link
PSTN Control BCC Protection
control
protocol protocol protocol protocol
protocol
module module module module
module

A、PSTN protocol：

PSTN protocol provides the procedure relating to specific calls.
it transmits the analog line status information(such as hook off
and hook on ) through the V5 interface.

B、Control protocol
The control protocol of the V5 interface consists of two parts:
common control and user port control.
The common control provides the operations relating to the whole
V5 interface, such as interface start, interface provisioning and the
block/unblock of all the user ports.

The user port control provides the operations relating to only one
port, including all types of ports, such as PSTN user port and
ISDN user port. These ports can be blocked, unblocked, activated
and deactivated.

C、Link control protocol
Fulfilling below functions:
Link status(normal、blocked、out of work)
management,blocking and unblocking the links.
Confirm links at both ends of the interface.(to make sure
whether the links are available).

D、BCC protocol
The BCC protocol controls the allocation and release of the B
channel.

E、protection protocol
The protocol provides the protection program for the

communication path switchover when a fault occurs.

4). V5 signaling procedure in PSTN service
A).call setup（user of AN originates a call）
User port AN LE
Off hook ESTABLISH

ESTABLISH ACK

ALLOCATION

ALLOCATION COMPLETE

Dialing tone

B).call release（AN user ends a call）
User port AN LE
On hook SIGNAL

DISCONNECT

DEALLOCATION

DISCONNCET ACK

DEALLOCATION COMP

V5 protocol English

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