Re: Spill over

["Chris Bennett" <chris@xxxxxxxxxx>]

A little googling tells me 250 ZAR ~ 42 USD.  Is this correct?  If so, ouch.. that's pricey.

 

3GB (assuming B in this case is BYTE) comes out to about 9kbit / second over a month, if I did my math correctly.  Ouch again.

 

Does the 3GB apply to the total of up and down traffic, or just down?  Because you can't control traffic coming to you very well.  You can try to control TCP traffic with policing, but UDP traffic does its own thing.  Not to mention jokers who decide to flood the link for the hell of it.

 

Given this new info, it sounds more like you shouldn't try to use the 512kbit link at all unless the 64kbit link goes down.  If you do try to push "excess" traffic onto it, all that does is encourage the use of applications that will consume the entire bandwidth available.  If that is really beyond your budget, it doesn't seem like something you'd want to do.  Better to set the expectations at 64kbit so the users don't get the idea of tuning into Internet radio or something.  In fact, if the 64kbit link does go down, it could be a good idea to police the 512kbit link down to 64kbit, just so the users don't jump for joy when the 64kbit link goes down... (keeping in mind that policing is no guarantee that you'll actually stay below 64kbit usage, especially if a lot of the traffic is UDP).

----- Original Message -----

From: Kenneth Kalmer

To: Chris Bennett ; Taylor Grant

Cc: lartc

Sent: Monday, April 25, 2005 2:48 AM

Subject: Re: Spill over

Taylor & Chris (and the list)

The arguments behind my choice here is cost driven, the 64kbps line is a fixed monthly rate for unlimited use, the 512kbps line costs us roughly ZAR250 per 3GB of usage. This can get quite expensive as the lines in question is for a college and we all know what students do to bandwidth :)

Taken the amount we pay every month for the 64kbps line it's more economical to over utilize the link as a primary connection than to have it lying around as a backup. South Africa and data connections don't go well in the same sentence...

As Chris suggested, I need something that can detect when Link A is saturated and then redirect the traffic over Link B until there is available bandwidth on Link A again. The rate limit trick of Taylor might work once I get to understand the usage patterns of these students. But for at least the first 3 months I won't have proper data at my disposal.

Thanks for your replies!

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