Copyright © 2005 Marconi Corporation plc. All rights reserved Network Timing ATM Switch

Copyright © 2005 Marconi Corporation plc. All rights reserved

Network Timing

ATM Switch

2 Copyright © 2005 Marconi Corporation plc. All rights reserved

Objectives

Explain the purpose of network synchronization Identify the meaning of the Stratum clocking grades Identify the internal and external timing components

associated with the CEC-Plus and ASX-4000 Series TCM Describe the basic distribution of timing architecture for line

timing and external timing sources Configure the IP interfaces on the CEC-Plus Configure and verify timing (external timing example) on the

CEC-Plus and the ASX-4000 Series TCM


Overview

Physical Links

Primary Reference Source (PRS)

ReferenceSource In

Distributed toall ports

Used fortransmission

Port


Timing Fundamentals

A timing element (a.k.a., clocking) is a pulse pattern A timing element can be seen from two perspectives:

Receive timing is derived from the incoming frame rate Transmit timing controls the outgoing frame rate

Frame rates are universal, even on different interface speeds

Interface Bit rate Frame rate

DS1 1.544 Mbps 8,000 fps

E1 2.048 Mbps 8,000 fps

DS3 44.736 Mbps 8,000 fps

E3 34.368 Mbps 8,000 fps

OC-3 155.52 Mbps 8,000 fps


Timing Precision

The integrity of a timing pulse can be classified by quality The goal is to have all the devices follow the same reference;

hence they are synchronized Normally the timing signal is derived from the most accurate

of clocks (referred to as a Stratum 1 traceable clock)

Stratum Accuracy Time until first Bit Slip following failure (Holdover)

1 1 x 10-11 or less 72 Days

2 1.6 x 10-8 7 Days

3E 1.0 x 10-6 3.5 Hours

3 4.6 x 10-6 6 Minutes


Impact of Timing Problems

When sending and receiving devices use different reference sources, bit slips and frame slips can result

The underlying problem is either buffer overrun or underrun Synchronized networks minimize these problems

buffer Framer

~8,000 fps(8,150 fps)

~8,000 fps(7,920 fps)

buffer Framer

~8,000 fps(7,885 fps)

~8,000 fps(8,215 fps)

Overrun example

Underrun example


Timing Structure

PRSPRSSecondary ReferenceSecondary Reference

Primary ReferencePrimary ReferenceStratum1Stratum1

Stratum1Stratum1

S4S4S4S4

S3S3S3S3

S2S2 S2S2

S4S4S3S3

Voice or VideoApplication

Voice or VideoApplication Voice or Video

ApplicationVoice or Video

Application

SRSSRS


TCM Types

ASX-1000/1200 and TNX-1100 Dual TCMs comprise the CEC-Plus Supports network timing subsystem and alarm relays Runs with or without switch fabrics installed

ASX-4000 Series TCM is a daughter card to the SCP Supports timing functions and alarm relays

Daughtercard


TCM Features

Hot-swappable ASX-4000 version is integral to SCP; must remove SCP

Redundant BITS inputs Line timing inputs

Hitless reference switching and failover Timing holdover Stratum 3 or 4 oscillator and digital phase lock loop Configurable alarm relay contacts


CEC-Plus: TCM Front Panel

25 pin D-sub: Alarm relay connections Normal open or normal closed wiring

Alarm LEDs: Alarm relay is normal or energized Ethernet connection to SCPs Serial port Status LED

Solid: Active Flashing: Standby Amber: Error

External timing signal ports (TX and RX) Reset button


ASX-4000 Series: TCM Front Panel

SCP front panel includes: 25 pin D-sub: Alarm relay connections

Normal open or normal closed wiring Alarm reset button

Returns relays to normal state Alarm LEDs: Alarm relay is

normal or energized Alarm Relay LEDs


Timing Distribution Architecture

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

P P P SSSS P

S

S

P

P

BITS-Y

BITS-X

TCM X

TCM Y

PLL

PLL


Line Timing Example

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

P P P SSSS P

S

S

P

P

BITS-Y

BITS-X

TCM X

TCM Y

PLL

PLL


BITS Timing Example

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

Fab

ric/Po

rt card

P P P SSSS P

S

S

P

P

BITS-Y

BITS-X

TCM X

TCM Y

PLL

PLL


Modes of Operation for TCM

Hitless modes move between available clock sources Line timing – references a network port

CEC-Plus: Automatic mode ASX-4000 Series: Line mode

BITS timing references an external source CEC-Plus: BITS mode ASX-4000 Series: External mode

Manual modes do not change sources FreeRun (internal oscillator) Primary (CEC-Plus only) Secondary (CEC-Plus only)


CEC-Plus Address Configuration

DDBB

CCAA

YY

XX

DDBB

CCAA

YY

XX

DDBB

CCAA

YY

XX

DDBB

CCAA

YY

XX

22 33 4411

YY

XX

TCM

TCM

TCM

TCM

TCM Interface IP Addressing

ie0 192.168.20.1

ie1 192.168.20.2

ie0 192.168.20.3

ie1 192.168.20.4

ASX-1000/1200/TNX-1100

Fabric 1ie0 192.168.20.5

SCP Addressing

Fabric 2

ie0 192.168.20.6

Fabric 3ie0 192.168.20.7

Fabric 4

ie0 192.168.20.8


CEC-Plus Management Interface - EMI

Extended Management Interface (EMI) Used to configure the IP addresses for the TCM interfaces (ie0 and ie1)

ATM Management Interface (AMI) Controls the CEC-Plus after IP addresses are configured on the

Timing Control Modules (TCMs) The syntax used for EMI is different than AMI


Configure the TCM’s IP Interfaces

localhost::> configurationlocalhost::configuration> iplocalhost::configuration ip> address ie0 192.168.20.1localhost::configuration ip> address ie1 192.168.20.2localhost::configuration ip> admin ie0 uplocalhost::configuration ip> admin ie1 up

localhost::configuration ip> show

interface state address netmask broadcast

ie0 up 192.168.20.1 255.255.255.0 192.168.20.255ie1 up 192.168.20.2 255.255.255.0 192.168.20.255lo0 up 127.0.0.1 255.0.0.0 N/A


Addressing the SCPs of the Switch

ATM SWITCH:interfaces ip-> mod ie0 192.168.20.5 -state upATM SWITCH:interfaces ip-> show

Interface State Address Netmask Neighbor Bcast MTU Address Settinglo0 up 127.0.0.1 255.0.0.0 N/A N/A 32768asx0 down N/A N/A N/A N/A N/Aqaa0 down N/A N/A N/A N/A N/Aqaa1 down N/A N/A N/A N/A N/Aqaa2 down N/A N/A N/A N/A N/Aqaa3 down N/A N/A N/A N/A N/Aie0 up 192.168.20.5 255.255.255.0 N/A 1 1500


VerifyReference Sources

Timing Configuration

Configure each fabric to listen to the

TCM Bus

Configure the TCM to listen to the PRS

and SRS

Configure Automatic Reference Source

Line Timing

BITS

Configure BITS Reference Source

(BITS)

Configure each fabric to listen to the

TCM Bus(CEC-Plus only)

Configure the Primary and

Secondary Line Timing Sources


BITS: Configure Fabrics to Use the TCM

Switch Fabric 1:system timing-> modify –timingmode tcmmode

Switch Fabric 1:system timing-> showTiming Mode: tcmModePrimary Clock: noneSecondary Clock: noneClock Status: tcm

(Repeat for each additional fabric)

CEC-Plus

This is the default for an ASX-4000 Series switch (no action needed)


Verify Reference Sources

Switch Fabric 2:hardware cecplus timing-> references show

Reference Source Status Admin RefQual

fabric1_Primary 1 (Down) unavailable up ok

fabric1_Secondary 1 (Down) unavailable up ok

:

fabric4_Primary 4 (Down) unavailable up ok

fabric4_Secondary 4 (Down) unavailable up ok

tcmX_bits1 BITS1 available up ok

tcmY_bits2 BITS2 unavailable up ok

ASX-4000:hardware tcm references-> show

Reference Source Status Admin RefQual

freerun freerun available up ok

bits1 BITS1 available up ok

bits2 BITS2 unavailable up N/A

switchPrimary none unavailable up N/A

switchSecondary none unavailable up N/A

ASX-4000 Series

CEC-Plus


Configure Timing Mode

ASX-4000:hardware tcm-> show

Operational Status: disabled

TCM Type: DS1_Stratum_3KTCM Version: 0TCM PLL Status: acquiring

Requested Timing Mode: externalOperational Timing Mode: external

Primary Timing Reference: bits1Secondary Timing Reference: bits2Current Timing Reference: primary:

ASX-4000 Series* This is the default for an ASX-4000 (verify with display)

Switch Fabric 1:hardware cecplus timing-> modify –mode bits

Switch Fabric 1:hardware cecplus timing-> show:BITS interface framing esfline coding b8zs , output level 0.6dB

PLL Status: acquiring

Current Timing Reference: BITS2Requested Timing Reference: bits:BITS1 Reference availableBITS2 Reference available:

CEC-Plus


Summary

Explained the purpose of network synchronization Identified the meaning of the Stratum clocking grades Listed the internal and external timing components

associated with the CEC-Plus and ASX-4000 Series TCM Described the basic distribution of timing architecture for line

timing and external timing sources Configured the IP interfaces on the CEC-Plus Configured and verify timing (external timing example) on the

CEC-Plus and the ASX-4000 Series TCM

Documents

Copyright © 2005 Marconi Corporation plc. All rights reserved Network Timing ATM Switch