TANDBERG D13192 manual Tandberg Gateway Capacity typical scenarios for 4Mb Option

Technical Description of TANDBERG Gateway with software version G2

4.1.8.1 TANDBERG Gateway Capacity – typical scenarios for 4Mb Option

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

Bandwidth	Non-encrypted		Encrypted
	(Max. no. of video		(Max. no. of video
	calls + telephone		calls)
	calls) IP & E1
128 kbps	8	+ 8	7
256 kbps	8	+ 7	6
384 kbps	8	+ 4	5
512 kbps	7	+ 4	5
768 kbps	5	+ 0	3
1472 kbps	2	+ 8	N/A
(1.5Mbps)
1920 kbps (2Mbps)	2	+ 0*	N/A

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

4.1.9Secure Conference (Encryption)

The TANDBERG Gateway has built-in encryption of audio, video and data for both H.323 (based on ITU standard H.235) and H.320 (based on ITU standard H.233 and H.234).

The encryption algorithms used in the TANDBERG Gateway and all other TANDBERG systems 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.Establishement of a common shared secret and selection of a 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

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