VPN Bandwidth Requirements

[Stephen Hope]

Philipp,

If you need bandwidth of 50k+ on a 64k line you already have a problem.....

Networks dont have steady state traffic, so you need some headroom. 100%
spare (ie.e 50% used) is a realistic compromise, but more is better. And the
next release will be bigger, use more bandwidth, do more things that eat
bandwidth.

also, the nearer you run to the link capacity the higher the latency, and it
follows an exponential curve as the %age of bandwidth used increases.

you can get by with little or no spare capacity but life will be difficult.

Also there is always extra background traffic, or contributions from other
application which will soak up "just a bit more".

Finally, there is always an unpleasant surprise - the last one that got me
was a month end file transfer which had to be moved in 2 hours because that
was the timeout for dial in, but it took 3......

Stephen

Stephen Hope C. Eng, Network Consultant, shope at energis-eis.co.uk,
Energis Integration Services Ltd, WWW: http://www.energis-eis.co.uk
Carrington Business Park, Carrington, Manchester , UK. M31 4ZU
Tel: +44 (0)161 776 4194 Mob: +44 (0)7767 256 180 Fax: +44 (0)161 776
4189


> -----Original Message-----
> From: Philipp Buehler [mailto:lists at FIPS.DE]
> Sent: 08 March 2001 14:08
> To: VPN at SECURITYFOCUS.COM
> Subject: Re: VPN Bandwidth Requirements
>
>
> On 08/03/2001, Renuka Nadkarni <renuka_nadkarni at YAHOO.COM>
> wrote To VPN at SECURITYFOCUS.COM:
> > I dont see how using a VPN can affect the bandwidth
> > requirement.
> Eh? If you have dialup ISDN you maybe can use e.g.
> 4 citrix clients or download at about 8kB/s.
> With IPSec you will have overhead IN the bandwidth.
> Calculation was done in previous mail.
>
> > Only thing that may change with use of a VPN is that
> > you have to make sure that the VPN gateway is not a
> > bottleneck. Most of the manufacturers have different
> > speeds of encryption so a right platform can be
> > chosen.
> I think bandwidth is the first point. *If* you have something
> timecritical you have a demand on bandwidth and latency.
> *Second* you design the gateway for that needs of encryption
> speed. Done.
>
> > I would first design the network and then purchase the
> > VPN equipment (firewall/router/hardware gateway) to do
> > encryption for the traffic.
> yes.
>
> > As such I think the bandwidth and vpn are diffrent
> > issue.
> No. e.g. I need 50-60kbit/s *raw* bandwidth. So in plain
> ISDN this would be ok, but not w/ IPSec additionally.
>
> ciao
> --
> Philipp Buehler, aka fips | sysfive.com GmbH | BOfH | NUCH |
> <double-p>
>
> #1: Break the clue barrier!
> #2: Already had buzzword confuseritis ?
>
> VPN is sponsored by SecurityFocus.COM
>

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