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Voip over VPN (IPSec)

Hi : I am looking for the overhead of running VoIP over VPN.

Looking for G729r8 codec with 20 ms voice payload.

would appreciate the breakout on the packet overhead.

thank you

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Re: Voip over VPN (IPSec)

The IPSEC overhead is not that bad, assuming you have enough bandwidth. As far as the latency, once the VPN is actually setup,it is roughly about the same as as without encryption

VoIP + IPSec Bandwidth Calculation

Configuration / Transform set options

IP GRE (Generic Routing Encapsulation)

IPSec Tunnel Mode

ESP (Encapsulating Security Protocol)

Encryption 3DES (esp-3des)

Authentication SHA-1 (esp-sha-hmac)

Layer 3 Packet Size

G.729 = 136 bytes @ 50 pps = 54,400 bps

G.711 = 280 bytes @ 50 pps = 112,000 bps

Layer 2 (FR / HDLC) Packet Size (+4 bytes)

G.729 = 140 bytes @ 50 pps = 56,000 bps

G.711 = 284 bytes @ 50 pps = 113,600 bps

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