RE: Router with bandwidth management

[John Tully <tully at mikrotik.com>]

Hello Brian,

I agree that it is very nice for ISPs to provide additional queuing 
features to give the best performance with TCP, but it is not the standard.

For most end users, the standard and basis of most contracts is a serial 
modem that is hard limited (by the physical properties of the link) to a 
certain max speed.  Giving the "burst" speeds and queuing features that 
improve their connection, will also discourage them from paying for a 
higher speed contract.  Of course, many ISPs offer the 'bursting' as a form 
of competition to get customers to choose their service.

My whole point is that it is not required for ISPs to take this into 
consideration -- though it is nice for the customer.

Of course the MikroTik offers bursting and queueing also -- except for on 
simple PPPoE rate limit settings (it is possible to put queuing rate 
settings also with an extra configuration).

John
www.mikrotik.com

>On Mon, May 19, 2003 at 10:30:35AM +0300, Mark Tinka wrote:
> > Are you then saying that the service provider should strive to give the
> > client more than the 256Kbps the client isn't feeling satisfied with?
>
>No - I'm saying that if I buy 256K, I should be given 256K with no packet
>loss, not 512K with packet loss.
>
> > In the client-provider SLA - "I can guarantee you 256Kbps as long as you
> > keep within 256Kbps or 32Kbps data trasnfer rate. I can't guarantee you 
> full
> > passage if you attempt to go beyond this capacity."
> >
> > Isn't this what the provider is trying to achieve for the client? If the
> > client wants to connect at speeds in excess of the 256Kbps, the provider is
> > obliged to bring him down to sanity, or else he upgrades and a new SLA is
> > written up.
>
>Yes, but the client almost certainly cannot control it themselves. Here's a
>more concrete example:
>
>      ethernet           DSL line (512K)
>   PC --------- DSL CPE ---------------- DSL LNS --------- Internet -- FTP
>             (e.g. Cisco 8xx)          (e.g. 72xx)                   server
>
>The client runs an FTP client on their PC. How many FTP client programs do
>you know which can be configured "don't download faster than 256K"? None
>that I know of. The FTP program accepts TCP data as fast as it is presented
>to it.
>
>Equally, you can't tell the FTP server "please don't send me data faster
>than 256K, because that would put me outside of my contract". It sends as
>fast as it can. And in any case, you might be talking to several remote
>servers at the same time down the same link; in order to remain within
>contract I would have to enforce that the *total* inbound bandwidth for all
>those sessions combined is under 256K.
>
>Either of the two Cisco boxes I have shown could slow my inbound data to
>256K without dropping packets - but that's not a feature provided by Cisco.
>
> > In what I have experienced, if a client has 128Kbps [16Kbps data transfer
> > rate], the application that can hog all this capacity will sustainably
> > maintain 16Kbps transfer rates at all times e.g. your favorite p2p 
> software.
> > All other clients sourcing the same IP address will suffer because they are
> > trying to exceed 128Kbps, and their packets will be dropped. In this case,
> > client hasn't kept his side of the SLA.
>
>I don't understand; are you mixing KBps and Kbps ?
>
>If a client is on the end of a 128Kbps leased line, then they should get
>16KBps data transfer - agreed.
>
>If the client is on the end of an ethernet, which is downstream of a Cisco
>with CAR set to 128Kbps, they will get less than 16KBps data transfer
>because of the packet loss, which means backoff delays and possibly useless
>out-of-order packets received (i.e. without selective retransmission, those
>packets will get sent again)
>
>Regards,
>
>Brian.
>
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