TANDBERG MCU Technical Description

Technical Description of TANDBERG MCU with software version D3

D12925 Rev. 03 1

Technical Description

of TANDBERG MCU

with software version D3

TANDBERG

D12925 Rev. 03

Technical Description of TANDBERG MCU with software version D3

D12925 Rev. 03 2

Table of contents

1

INTRODUCTION ............................................................................................................................................ 5

2

PRODUCT DESCRIPTION............................................................................................................................ 6

2.1 SOFTWARE VERSIONS..................................................................................................................................... 6

3

OPERATION AND USER INTERFACE ...................................................................................................... 6

4

MCU INTERFACES & FEATURES ............................................................................................................. 7

4.1 NETWORK INTERFACES AND FEATURES ......................................................................................................... 7

4.1.1

Mixed ISDN and IP Conferences.............................................................................................................. 8

4.1.2

Multiple conferences................................................................................................................................. 8

4.1.3 PRI E1/T1 ISDN ....................................................................................................................................... 8

4.1.3.1

ISDN numbers ................................................................................................................................................. 8

4.1.3.2 PRI E1/T1 ISDN.............................................................................................................................................. 9

4.1.4 Ethernet / LAN Interface (H.323) ........................................................................................................... 11

4.1.4.1

Quality of Service features (QoS) .................................................................................................................. 11

4.1.4.2 Automatic selection of H.323 or H.320 outgoing calls.................................................................................. 12

4.1.4.3

IP adaptive bandwidth management .............................................................................................................. 12

4.1.4.4 Dynamic playout buffering ............................................................................................................................ 12

4.1.4.5 Asymmetrical media capabilities ................................................................................................................... 12

4.1.4.6

Diagnostic tools for IP................................................................................................................................... 13

4.1.4.7 Latency & Jitter ............................................................................................................................................. 13

4.1.4.8 Layer 4 Ports used in H.323 meetings ........................................................................................................... 13

4.1.4.9

IP packet sizes ............................................................................................................................................... 14

4.1.4.10 Intelligent Packet Loss Recovery (IPLR) ...................................................................................................... 14

4.1.5

LEDs Description ................................................................................................................................... 15

4.1.5.1 Description of PRI Alarms ............................................................................................................................ 15

4.1.6 Intelligent Call Management (ICM) ....................................................................................................... 16

4.1.7 MCU Capacity ........................................................................................................................................ 17

4.1.7.1

MCU Capacity – typical scenarios................................................................................................................. 18

4.1.8

Dial Profiles............................................................................................................................................ 18

4.1.9

Secure Conference (Encryption)............................................................................................................. 19

4.1.9.1 Number of encrypted sites (software option 16+16)...................................................................................... 20

4.1.9.2 Number of encrypted sites (software option 8+8).......................................................................................... 20

4.1.10

MCU control (H.231/H.243).............................................................................................................. 20

4.1.10.1 H.243 Password............................................................................................................................................. 21

4.2

A

GGREGATION

S

TANDARDS

......................................................................................................................... 22

4.2.1

BONDING............................................................................................................................................... 22

4.2.1.1 ISDN channel set-up...................................................................................................................................... 22

4.2.2

H.221 ...................................................................................................................................................... 22

4.2.3 H0 ........................................................................................................................................................... 22

4.3

RS232 I

NTERFACE

/A

PPLICATION

P

ROGRAMMABLE

I

NTERFACE

(API) ......................................................... 23

4.3.1 API commands........................................................................................................................................ 23

4.4

V

IDEO

F

EATURES

......................................................................................................................................... 24

4.4.1

Optimised Video Compression................................................................................................................ 24

4.4.1.1 The ITU standard H.263 provides ................................................................................................................. 24

4.4.1.2 The ITU standard H.264................................................................................................................................ 24

4.4.2

Video Formats ........................................................................................................................................ 25

4.4.3

Asymmetric Video Formats..................................................................................................................... 25

4.4.4 Best Impression....................................................................................................................................... 25

4.4.4.1

Dynamic/Auto Layout switching ................................................................................................................... 25

4.4.4.2

Automatic Resolution switching.................................................................................................................... 27

4.4.4.3 Video Transcoding ........................................................................................................................................ 28

4.4.5

Duo Video ............................................................................................................................................... 29

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4.4.5.1 Duo Video Interoperability with other vendors ............................................................................................. 29

4.4.6

Custom pictures ...................................................................................................................................... 30

4.5

AUDIO FEATURES ......................................................................................................................................... 31

4.5.1 Audio levelling/ Automatic Gain Control (AGC).................................................................................... 31

4.5.2

Telephone Noise Suppression ................................................................................................................. 31

4.5.3 Custom Sounds........................................................................................................................................ 31

4.5.4

Entry/Exit tones ...................................................................................................................................... 31

4.5.5

Muting of audio ...................................................................................................................................... 31

4.5.6 Telephony................................................................................................................................................ 32

4.5.7

Allow G.728 ............................................................................................................................................ 32

4.5.8

Audio Compression Algorithms .............................................................................................................. 32

4.6 SYSTEM MANAGEMENT................................................................................................................................33

4.6.1

Ethernet/LAN Interface........................................................................................................................... 33

4.6.2 Platform Requirements ........................................................................................................................... 33

4.6.3

Protocols Supported ............................................................................................................................... 34

4.6.4

System Management Functionality......................................................................................................... 34

4.6.4.1 Remote software upgrades using FTP: .......................................................................................................... 34

4.6.4.2 Management using a standard Web-browser: ................................................................................................ 34

4.6.4.3

Management using a standard Telnet-client: ................................................................................................. 35

4.6.4.4 Management using a terminal connected to the RS232 port:......................................................................... 35

4.6.5

Security ................................................................................................................................................... 35

4.6.5.1 HTTPS, TLS/SSL .......................................................................................................................................... 35

4.6.5.2 Disable Services............................................................................................................................................. 36

4.6.5.3

Security Alert................................................................................................................................................. 36

4.6.5.4 Authentication of Remote Management System – (Telnet Challenge) .......................................................... 36

4.6.6

Layer 4 ports used by the system ............................................................................................................ 37

5

MISCELLANEOUS FEATURES ................................................................................................................. 38

5.1 DISTRIBUTED MCUS .................................................................................................................................... 38

5.2

P

HONE BOOK

................................................................................................................................................ 39

5.2.1

Group Entries ......................................................................................................................................... 39

5.3 MAXIMUM MEETING DURATION.................................................................................................................... 39

5.4

F

ILE SYSTEM

(FTP) ...................................................................................................................................... 39

5.4.1

Picture files ............................................................................................................................................. 40

5.4.2 Sound files............................................................................................................................................... 40

5.4.3

Other files ............................................................................................................................................... 40

6

ENVIRONMENTAL ISSUES ....................................................................................................................... 41

6.1

TANDBERG’S ENVIRONMENTAL POLICY ................................................................................................... 41

6.2 ENVIRONMENTAL CONSIDERATIONS............................................................................................................. 41

7

PRODUCT APPROVALS ............................................................................................................................. 42

7.1 CONNECTION OF TELE-TERMINAL EQUIPMENT ............................................................................................ 42

7.2

EMC E

MISSION

- R

ADIATED

E

LECTROMAGNETIC

I

NTERFERENCE

................................................................ 42

7.3 EMC IMMUNITY........................................................................................................................................... 42

7.4

E

LECTRICAL

S

AFETY

.................................................................................................................................... 42

7.5

EMC IMMUNITY........................................................................................................................................... 42

7.6 NEBS APPROVAL ......................................................................................................................................... 43

8

PRODUCT RELIABILITY........................................................................................................................... 43

9

TECHNICAL SPECIFICATION OF TANDBERG MCU ......................................................................... 44

9.1 MECHANICAL INFORMATION......................................................................................................................... 44

9.2

P

ACKAGING

.................................................................................................................................................. 44

9.3

OPERATING TEMPERATURE AND HUMIDITY ................................................................................................. 45

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9.4

STORAGE AND TRANSPORT TEMPERATURE .................................................................................................. 45

9.5 SYSTEM POWER CONSUMPTION ................................................................................................................... 45

10

TECHNICAL SPECIFICATION SHEET ...................................................................................................46

Technical Description of TANDBERG MCU with software version D3

D12925 Rev. 03 5

1 Introduction

The TANDBERG MCU is a Multipoint Control Unit designed for connecting up to 16

videoconferencing endpoints and 16 telephones (i.e. 32 sites in total) in the same meeting giving

all participants the same high quality video and/or audio as if they were connected in a point-to-

point meeting.

The MCU implements the ITU-T H.320 standard for video compression and a combination of

H.221 and BONDING for communication on up to 30 ISDN B-channels as well as ITU-T H.323

v.4 standard for communication up to 2 Mbps over IP networks.

The TANDBERG MCU is ‘configurationless’ in the sense that no extensive knowledge is

required for installation and maintenance. All features are included in the MCU – thus, there is

no additional hardware required to use any of the inbuilt features.

All features of the TANDBERG MCU are based on standards set by the ITU-T.

The TANDBERG MCU is best utilised when used together with TANDBERG Management

Suite (TMS) and TANDBERG Scheduler, since they have incorporated features like Graphical

monitoring and Scheduling (Optional).

Major features supported:

• Up to three separate and independent conferences

•

Mixed ISDN/IP conferences

• Best Impression (i.e. a variety of picture layouts)

• Custom video formats (e.g. XGA video resolution)

•

Full implementation of Downspeeding

• Secure Conference (AES Encryption)

• Duo Video

• Up to 16 videoconferencing endpoints + 16 telephones

• Support for TANDBERG Scheduler and TMS - TANDBERG Management Suite -

(Optional)

• The ITU-T standard H.264 video compression algorithm

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2 Product Description

The TANDBERG MCU is built on a standard 19-inch rack mounted chassis of only 1U in

height.

2.1 Software Versions

There are two software options for the TANDBERG MCU; differentiated by maximum possible

number of sites:

• 8 video endpoints + 8 telephone endpoints (i.e. total of 16)

•

16 video endpoints + 16 telephone endpoints (i.e. total of 32)

Upgrading from the standard version 8+8 to the optional 16+16 is easily done by entering

Software Option keys inserted e.g. via the MCU’s web interface.

3 Operation and User Interface

The TANDBERG MCU is normally controlled via the web interface, but any user may schedule

meetings on the MCU by using the TANDBERG Management Suite (TMS) or the TANDBERG

Scheduler.

The TANDBERG MCU can also be controlled via Telnet (or the RS232 port) by using a

comprehensive set of API commands

1

. This enables the MCU to be controlled by a different user

interface, such as an AMX or Crestron control systems.

For information on how to operate the system, please see the documents TANDBERG MCU User

Manual or TANDBERG MCU API supplied with the system.

1

Please, refer to document ‘TANDBERG MCU API’ (D12930)

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4 MCU Interfaces & Features

Extensive use of industry standard interfaces and connectors ensure effortless integration of

external equipment with the TANDBERG MCU. These interfaces can easily be controlled via

one of the intuitive user interfaces.

4.1 Network Interfaces and Features

Network Interfaces 4 x PRI (RJ-45 Jack) Primary Rate (G.703) Interfaces

2 x Ethernet (RJ-45 Jack) LAN interfaces (10/100 Mb)

2

• 4 x PRI (RJ-45 jack) Primary Rate (G.703) interface for transmission speeds from 56

kbps up to 2 Mbps (1.5 Mbps PRI/T1).

•

2 x Ethernet (RJ-45 jack) Local Area Network interface (10/100Mb) for transmission

speeds up to 2 Mbps

2

.

2

Only Ethernet port no. 1 is used in software version D3 (Ethernet port no.2 is for future use).

2 LAN ports 4 ISDN PRI ports 1 RS232 port

4 Fans

P

ower connector

+ Power switch

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4.1.1 Mixed ISDN and IP Conferences

The MCU allows for using both ISDN and IP networks in same conference. In addition,

telephone sites (IP or ISDN) can also be included in the same conference.

The maximum IP, ISDN and mixed mode capacity is described in chapter 4.1.7. All conferences

may use the normal features of TANDBERG products such as Duo Video, Encryption etc.

4.1.2 Multiple conferences

The TANDBERG MCU may run three separate videoconferences at the same time. The

meetings will be independent of each other as long as no resource restrictions apply (i.e.

bandwidth/number of sites).

Note: If the MCU is not registered to a Gatekeeper it is only possible to dial into conference

number 1 (via H.323).

4.1.3 PRI E1/T1 ISDN

4.1.3.1 ISDN numbers

The PRI lines connected to the MCU should have at least one number each, to allow dial in

from ISDN.

Number Range Start:

If the PRI line has a range of numbers, the start number should be entered in the Number Range

Start field. The number range must be inclusive. All numbers in the range may be used by the

MCU for callback numbers, so the local ISDN switch must route all of these numbers to the

configured PRI. It is only necessary to enter the digits indicating the range. If the range is

67828669 to 67828699, then just enter 8669. Maximum amount of digits is 24.

Number Range Stop:

The last number in the PRI number range is entered in the Number Range Stop. If the range is

67828669 to 67828699, then just enter 8699.

PRI Trunk Grouping:

When Trunk Grouping is enabled, PRI 2, 3 and 4 will use the same number range as specified

for PRI 1.

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4.1.3.2 PRI E1/T1 ISDN

The PRI interface may require an external CSU depending on the network layout. ‘Cable

Length’ in the PRI set-up menu specifies the distance from the MCU to the CSU or last repeater.

A CSU should not be required if the system is within 200 m (655 ft) of the last repeater

depending on the PRI cable quality.

The TANDBERG MCU supports the PRI protocols AT&T Custom, National ISDN and ETSI

(Euro ISDN). The AT&T and National protocols will give a total of (23*4) = 92 channels while

the ETSI protocol will give a total of (30*4) = 120 channels.

Within these protocols the following switches are supported:

Switches

Protocols supported

4ESS (AT&T) AT&T Custom

5ESS (AT&T) AT&T Custom and National ISDN

3

DMS250 (Nortel) National ISDN

DMS100 (Nortel) National ISDN

(Any switch) ETSI (Euro ISDN)

Channel hunting is provided for outgoing calls. The feature is normally used when the number

of channels needs to be specified. When no value is specified for low or high channel, they

default to 1 (low), 23 (high US) and 30 (high Europe). Default search is from high to low.

Pinout of PRI E1/T1 Interface:

4

NOTE: TANDBERG recommends always using category 5 cabling.

3

Dependent on the configuration of the switch

4

The cable of use should be a straight through configuration.

PRI Pinout

1 TIP RX

2 RING RX

4 RING TX

5 TIP TX

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PRI T1 (US only):

Network Service Facility (NSF) can be configured as blank/no value (i.e. NSF not used –

default) or any value between 0 and 31, to describe the service facility on the PRI/T1 line.

AT&T

Service code (ref.1)

Service

0 Disable

1 SDN (Including GSDN)

2 Toll Free Megacom (800)

3 Megacom

6 ACCUNET Switched Digital Service (incl. Switched Digital International)

7 Long Distance Service (incl. AT&T World Connect)

8 International Toll Free Service (1800)

16 AT&T MultiQuest

23 Call Redirection Service

Sprint

Service code (ref.2)

Service

MCI

Service code (ref.2)

Service

0 Reserved 1 VNET/Vision

1 Private 2 800

2 Inwatts 3 PRISM1, PRISMII, WATS

3 Outwatts 4 900

4 FX 5 DAL

5 TieTrunk

Ref. 1: AT&T TR 41459 Specification, June 1999, page 76

Ref. 2: Ascend Multiband Plus-T1/PRI, User Documentation, Page 6-8

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4.1.4 Ethernet / LAN Interface (H.323)

The TANDBERG MCU have two RJ-45 jacks

5

for the Ethernet interface (manual or automatic

detection of 10/100Mb) and supports call rates from 56 kbps up to 2 Mbps. The ITU-T standard

H.323 v4 protocol is implemented in the TANDBERG MCU.

The following features are specifically relevant for this network interface:

4.1.4.1 Quality of Service features (QoS)

4.1.4.1.1 IP precedence

IP precedence is a classification of packets from 0 (low priority) to 7 (high priority). The

values 6 and 7 are typically reserved for congestion control. IP precedence helps a router

select what kind of traffic to prioritise. By means of queue mechanisms, it can select

which packets to send first and which to throw away. Some information/traffic is time

critical while other is not, and classification is used to differentiate this traffic.

One may set separate IP precedence for Signalling, Audio, Video and Data (values 1 – 7)

as well as turn IP precedence off.

The auto setting uses the following values for IP precedence:

Signalling=6

Audio/Video=4

Data=3 (e.g. FECC commands)

This means that in auto, IP precedence has the value 6 (i.e. signalling value) while both

audio and video value is 4; data value is 3. Setting the IP precedence value in system’s

menu is actually setting the signalling value. The audio/video and data values are

changed accordingly in respect to the signalling value (i.e. audio/video value = - 2; data

value = - 3).

4.1.4.1.2 Diffserv

Diffserv is an extension of IP precedence, where one can set values from 0 to 63

(63=Highest priority).

5

Ethernet port no.2 is not used in software version D3.

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4.1.4.1.3 IP type of service (TOS)

TOS helps a router select a routing path when multiple paths are available.

Delay- tells router to minimize delay

Throughput- tells router to maximize throughput

Reliability- tells router to maximize reliability

Cost- tells router to minimized cost

Off- Turns TOS off

4.1.4.1.4 Resource-Reservation Protocol (RSVP)

RSVP is a protocol that allows the TANDBERG MCU to request the network to reserve

the bandwidth needed for the IP meeting.

4.1.4.2 Automatic selection of H.323 or H.320 outgoing calls

• IP address or E.164 number dialling.

• Automatic selection based on network address type or predefined prefixes.

4.1.4.3 IP adaptive bandwidth management

•

The MCU never produces more traffic than needed, for better utilization of network

resources. Most of the data sent in a videoconference is video data. Thus, by

incorporating smart video algorithms, the codec sends no more video data than

necessary. Little movement in the picture gives low bit rate; while a lot of movement

gives higher bit rate.

• The MCU regulates outgoing and incoming media bit rates by means of flow control

signalling.

An example of this is automatic adjustment of total bandwidth used when DuoVideo is

opened.

4.1.4.4 Dynamic playout buffering

Shapes the incoming data for better playout and re-sequencing of packet delivered out of

order. This ensures better lip sync.

4.1.4.5 Asymmetrical media capabilities

Audio and video protocols can be fully asymmetrical.

E.g., the TANDBERG MCU can send H.263 and receive H.261 at the same time.

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4.1.4.6 Diagnostic tools for IP

Q.931 To show Q.931 trace during a conference you need to issue the command syslog

on. One can get traces for RAS, Q.931 and H.245 with this command. It is a

complex trace and requires an extensive knowledge in H.323 signalling to be

understood.

Ping Ping is used to see if the MCU is able to reach a specific IP-address, using a

mechanism in IP called ICMP. If the MCU is unable to register to its gatekeeper,

or if it is unable to dial a specific endpoint, one can use ping to see if there is at

least an IP-route to the gatekeeper or to the endpoint. In case you have problems,

one would first ping the default gateway, then the gatekeeper, and then the other

endpoint.

Traceroute Traceroute does exactly that; it traces the route an IP-packet takes to reach its

destination and displays all router hops. Traceroute is very useful for seeing

exactly where there is a routing-problem in the IP-network, and for checking

where transport-delay is introduced.

4.1.4.7 Latency & Jitter

Latency is defined as the time between a node sending a message and receipt of the

message by another node. The TANDBERG MCU can handle any value of latency-

however, the higher the latency, the longer the delay in video and audio. This may lead

to conferences with undesirable delays causing participants to interrupt and speak over

each other.

Jitter is defined as the difference in latency. Where constant latency simply produces

delays in audio and video, jitter can have a more adverse effect. Jitter causes packets to

arrive out of order or at the wrong times, which again leads to packet loss. TANDBERG

MCU can manage packets with jitter up to 100ms. If excessive packet loss is detected,

the TANDBERG MCU will downspeed the connection until acceptable packet loss is

achieved.

4.1.4.8 Layer 4 Ports used in H.323 meetings

The following tables describes what layer 4 ports are being used by the system when call

is made on an H.323 network.

MCU meetings + Duo Video

Function Port Type

Gatekeeper Discovery (RAS) 1719 UDP

Q.931 Call Setup Range 5555—5587 TCP

H.245* Range 5555—5587 TCP

Video Range 2326—2837 UDP

Audio Range 2326—2837 UDP

Data/FECC Range 2326—2837 UDP

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4.1.4.9 IP packet sizes

Audio

The system automatically selects the most favorable IP packet size for audio. Depending on

the network conditions, the system will send 20 ms or 40 ms of audio in each packet, thus:

• G.711 – 160/320 bytes per packet

• G.728 – 40/80 bytes per packet

• G.722 – 160/320 bytes per packet

• G.722.1 (24 kbps) – 60/120 bytes per packet

• G.722.1 (32 kbps) – 80/160 bytes per packet

Video

The TANDBERG MCU is sending maximum 1450 bytes of video per packet.

Note:

In addition, the system needs to add the following header information for each of the audio

and video packets above:

20 bytes IP-header, 8 bytes UDP-header and 12 bytes RTP-header (i.e. 40 bytes in total).

Packet loss:

Packet loss is displayed in the conference overview of the MCU. The number

shown is the average of audio- and video- packets that are lost during the last 2 seconds.

4.1.4.10 Intelligent Packet Loss Recovery (IPLR)

IPLR is an ITU standard based packet loss compensation for H.323 that improves received

video into the TANDBERG MCU. IPLR supports all video protocols and resolutions that

TANDBERG MCU already has implemented and is compatible with all terminals and

Gateways.

IPLR is a special algorithm developed at TANDBERG that will make efforts to reconstruct

the lost packets and reduce the visual effects caused by packet losses.

• If the MCU experiences packet loss from an endpoint, it will ask the endpoint to handle

packet loss. This requires Intelligent Packet Loss Recovery functionality on the endpoint.

• If an endpoint experiences packet loss from the MCU, the MCU encoder will not start

IPLR since this would affect the received video quality for all other endpoints.

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4.1.5 LEDs Description

The TANDBERG MCU has 24 LEDs (Light Emitting Diodes) on the front panel, each giving

various information as shown below.

4.1.5.1 Description of PRI Alarms

A PRI cable consists of four wires (2 pairs of wires): One pair for Transmit (TX) and one pair

for Receive (RX) signals.

Red Alarm

Red alarm or Loss of signal (LOS) means that there is no signal and thus no framing info

received. (This has same effect as pulling out the PRI cable).

Yellow Alarm

Yellow alarm or Remote Alarm Indicator (RAI) means that the MCU is receiving framing info,

but in this framing info the other side tells the MCU that it is not reading the MCU’s transmitted

framing info. Typically, this may be a broken connector in the TX part of the MCU PRI cable.

This could also indicate weak or noisy signal in the TX part of the MCU PRI cable.

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Blue Alarm

Blue alarm means that network on the far side of the CSU is unavailable.

Scenario: TANDBERG MCU is connected via a CSU (i.e. a NT ‘Network Termination’) as

follows:

MCU

–cable A–CSU–cable B–Network

If a CSU loses framing/sync from the network (example: a bad cable B), it shall no longer send

valid framing out on cable A towards the MCU. Instead it transmits "Blue Alarm". Seen from

the MCU receiving blue alarm, this means that the network on the far side of the CSU is

unavailable.

4.1.6 Intelligent Call Management (ICM)

By using TANDBERG's inbuilt Intelligent Call Management (ICM), MCU conferences can be

made from data rates of 56 kbps up to 2 Mbps via ISDN networks.

ICM is a highly sophisticated feature provided by the TANDBERG MCU that e.g. makes the

connection between two sites more reliable and safe. If the ISDN network drops channels

during a meeting, the conference will not shut down but adjust to the remaining number of

available channels

6

. This ability is called ‘Downspeeding’ and is in accordance to the

BONDING Mode 1 standard.

Downspeeding will take place in the following situations:

a) When sites are entering the conference with a lower bandwidth than what is defined in

that particular conference’s set-up.

In this case, the MCU will receive different call rates from the connected sites, but will

transmit the call rate of the site with lowest call rate capabilities.

b) When a site is loosing a channel.

In this case the MCU will still receive different call rates from the connected sites, but

will transmit the call rate of the site with lowest call rate capabilities.

If the site loosing a channel is disconnected, the MCU will automatically send out the

call rate initially set up for that conference.

6

If one of the connected sites does not support downspeeding, this site will drop out of the call and this call needs to be set up again.

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4.1.7 MCU Capacity

The total capacity of the MCU is defined by the following three rules.

RULES:

I. Software version defines maximum number of sites:

8+8 -> Maximum 8 video sites and maximum 8 telephones

16+16 -> Maximum 16 video sites and maximum 16 telephones

II. Total system bandwidth of the MCU is 7680 kbps (IP and ISDN) regardless of

software version. The maximum bandwidth used for ISDN calls is depending on the

number and type of PRI's installed:

a) The maximum bandwidth for ISDN E1 is 7680 kbps (120x64 kbps, if all 4

PRI's are installed).

b) The maximum bandwidth for ISDN T1 is 5888 kbps (92x64 kbps, if all 4 PRI's

are installed).

III. In addition, each call has a

Call Weight

depending on bandwidth and encryption as

follows:

Video sites:

Bandwidth

64

128 192 256 320 384 512 768 1152 1472 1920

Non-encr.

37

40 41 42 44 46 54 62 80 88 110

Encrypted

53

59 60 61 68 73 84 111 N/A N/A N/A

Telephone sites:

Bandwidth Telephone

Non-encr.

11

Encrypted

N/A

The sum of the Call Weights cannot exceed 845.

(Users will be prevented from setting up calls that exceeds this limit).

Example of call weight calculation:

If the MCU has made 6 calls at 768 kbps, 4 calls at 384 kbps, and 4 encrypted calls at 192 kbps

the calculation will be:

6x62 + 4x46 + 4x60 = 796.

Since 796 is less than 845, this will be OK.

Technical Description of TANDBERG MCU with software version D3

D12925 Rev. 03 18

4.1.7.1 MCU Capacity – typical scenarios

In the table below some typical capacity scenarios are listed (they can be derived by the

calculation above):

Bandwidth Non-encrypted

(Max. no. of video

sites + telephone

sites)

IP & E1

Non-encrypted

(Max. no. of video

sites + telephone

sites)

T1 only

Encrypted

(Max. no. of video

sites)

128 kbps 16 + 16 16 + 16 14

256 kbps 16 + 15 16 + 15 13

384 kbps 16 + 9 15 + 2** 11

512 kbps 15 + 0* 11 + 4** 10

768 kbps 10 + 0* 7 + 8** 7

1472 kbps

(1.5Mbps)

5 + 5 4 + 0** N/A

1920 kbps (2Mbps) 4 + 0* 3 + 2** N/A

*) Limited by the maximum capacity 7680 kbps, see rule II a) above.

**) Limited by the maximum capacity 5888 kbps, see rule II b) above

4.1.8 Dial Profiles

The TANDBERG MCU can be programmed to use different Dial Profiles. Dial Profile consists

of a name and a prefix.

Example:

If 0 (zero) is needed to call outside a location, create a prefix called ‘external’ with prefix set to

0.

Also, to differentiate between ISDN numbers/E.164 Alias the ‘Dial Profiles’ shall be extended

to support selection of ‘ISDN’ & ‘H.323’.

Technical Description of TANDBERG MCU with software version D3

D12925 Rev. 03 19

4.1.9 Secure Conference (Encryption)

The TANDBERG MCU has built-in encryption of audio, video and data for both H.323

meetings (based on ITU standard H.235) and H.320 (based on ITU standard H.233 and H.234)

meetings. The administrator decides- when setting up the conference- whether or not a

conference shall be in encrypted mode or in unencrypted mode. It is not possible to change the

mode after the conference is set up.

The encryption algorithms used in the TANDBERG system are:

- The Data Encryption Standard (DES) with a 56 bits session key

- The Advanced Encryption Standard (AES) with a 128 bits session key

Although there are small differences between H.323 and H.320, a typical set-up of a secure call

can be defined as follow:

1. Establishment of a common shared secret and selection of an encryption algorithm.

2. Exchange of the keys according to the common shared secret and the selected encryption

algorithm.

3. Start the encryption.

The establishment of the common shared secret is done through the computation of the Diffie-

Hellman (DH) algorithm. The DH method uses primes numbers of 512 bits length for DES and

1024 bits for AES. The shared secret is then used as a key for the selected encryption algorithm

which encrypts "the session keys". When the session is collected by the remote end, encryption

of the audio, video and data channels can start.

The encryption will be established automatically when all endpoints in the conference supports

encryption with automatic key generation (and the conference is set up for encryption mode of

operation).

Encryption is supported for meetings up to 768 kbps and the TANDBERG feature DuoVideo.

Note: For an encrypted conference, all endpoints must support encryption (AES or DES).

- If encryption mode is set to Auto, the MCU accepts both AES and DES encryption.

- The MCU administrator can also force the MCU to require only e.g. AES encryption. In this

case, all participants must have AES in order to join the conference.

If a site entering an encrypted conference does not support encryption, a picture will be

shown, informing that the conference requires encryption.

If a site connected to an encrypted conference start sending unencrypted data, that site

will be taken out of the conference.

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D12925 Rev. 03 20

4.1.9.1 Number of encrypted sites (software option 16+16)

Bandwidth video sites

(in kbit/s) 128 256 384 512 768

Number of encrypted sites

14 13 11 10 7

The above table shows the maximum number of sites and at what meeting bandwidth, a

conference can be encrypted with MCU 16+16 software option.

4.1.9.2 Number of encrypted sites (software option 8+8)

Bandwidth video sites

(in kbit/s) 128 192 256 320 384 512 768

Number of encrypted sites

8 888887

The above table shows the maximum number of sites and at what bandwidth, a conference can

be encrypted with MCU software option 8+8.

4.1.10 MCU control (H.231/H.243)

For controlling the TANDBERG MCU conference the following options are implemented:

•

H.243 MCV Take Floor

This feature is used by any of the connected sites.

I.e. any site may Request floor to broadcast their video to all sites, and Release floor to

go out of broadcast mode (applicable for both ISDN and IP meetings).

•

Assigning Floor

This feature is used by the administrator of the MCU.

I.e. The administrator may decide which site’s video shall be broadcasted to all

participants.

Terminal Site naming:

The TANDBERG MCU also supports site naming (on ISDN and IP).

Thus, if the connected sites also support site naming, a transparent line

of the broadcaster’s site name will be displayed (for approx. 10

seconds) on all other sites every time the TANDBERG MCU switches

broadcasting site. To view the sites connected to the conference, the

quick keys may be used on the EPs remote control.

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TANDBERG MCU Technical Description

TANDBERG MCU Technical Description

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