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RE: VoIP over IPsec
- From: Charles Youse
- Date: Mon Feb 17 13:40:08 2003
Using hardware encryption with the qos pre-classify feature, I imagine that jitter will no longer be an issue - (that is, the jitter you mention previously is introduced by the lack of prioritization into the encryption queue). Or am I missing something?
From: Stephen Sprunk [mailto:email@example.com]
Sent: Monday, February 17, 2003 2:24 AM
To: Charles Youse
Subject: Re: VoIP over IPsec
Thus spake "Charles Youse" <firstname.lastname@example.org>
> In order to cut costs in our telecom budget I'm toying with the idea
> of replacing a lot of our inter-office leased lines with VPN
> connections over the public Internet. [...]
> Assume for the moment that latency and bandwidth are not an issue;
> e.g., any two points that will be exchanging voice data will both have
> transit from the same provider with an aggressive SLA.
Latency, bandwidth, and packet loss are moot. Jitter is VoIP's enemy.
> Does anyone have any experience running VoIP over such tunnels?
> Is there a technical reason why this solution is not feasible? Are
> Cisco routers not happy doing VoIP/IPsec/GRE in concert?
IPsec itself will not cause you problems; there's no theoretical conflict.
Unfortunately, IOS can introduce jitter when encrypting packets. To
mitigate this, you can apply QOS, with a strict priotiy queue for the VoIP
packets and the "qos pre-classify" feature. Your mileage will vary
depending on the CPU power of the router, the traffic levels, and whether
you're using hardware encryption.
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking