[asterisk-users] Connecting branch offices through IPsec tunnel --latency effects?

[Tim Panton]

On 26 Jul 2006, at 02:00, Rich Adamson wrote:

> Dan Austin wrote:
>> Stephen wrote:
>>> If I connect two offices through an IPsec tunnel, what is the impact
>> on
>>> latency, and does it noticeably affect calls?
>> That would depend a lot on the equipment that services the IPSEC  
>> tunnel
>> endpoints.
>>> Has anyone out there tried this? What were the effects?
>> I've run small to mid size offices (20 to 60 people) over IPSEC
>> tunnels during periods of internal network failures with good  
>> results.
>> That includes offices on the opposite side of the world with one-way
>> latency normally around 100ms, but often up to 160ms.
>> Using commercial IPSEC endpoints, or OpenSWAN on a decent system only
>> adds a couple of ms, if that.
>
> I might add that I did a little research for a non-voip project  
> relative to what cisco 28xx routers could sustain in terms of ipsec- 
> vpn throughput. The cisco doc's report 55 mbs sustained throughput.
>
> On the flip side, the older cisco routers can't sustain 500 kbs  
> without adding a hardware encryption board to the router.
>
> So, you are probably very right with the "depends a lot on the  
> equipment". ;)

In some cases it seems that VPN might get you less latency!
I hear that some 3g carriers prioritize VPN traffic above VOIP traffic.


Tim Panton

www.mexuar.com