[c-nsp] Re: Traffic Shaping packet loss

[Kanagaraj Krishna]

Dan,
   Our customers co-locate with us and are directly connected to the switch. 
Its just that, we provide MRTG access to customers who want to monitor their 
traffic utilization. By setting the burst rate high, i don't want the customer 
to think they are getting more than they subscribed. Another thing is that for 
business reason, if the MRTG shows the traffic is hitting the cap (just say 
64K and not more), we can ask them to upgrade. Any comments?

Kana

> Yes, you're right. 
> 
> This is a tough one to get, but your ping problem is a perfect teaching
> tool.
> 
> Think of it like this.  take your packets per second setting and divide
> it by a thousand, because I suck at math, lets say it's a thousand
> packets per second.  That means every millisecond, you have the right to
> send one packet across that port.  I know, its not in packets, its in
> bytes, but bear with me for another moment.
> 
> If two packets show up during that millisecond, one gets dropped.  It
> doesn't matter how many packets showed up the millisecond before or the
> millisecond after.
> 
> If you increase the burst size and your pings get through, that tells me
> that there is not something else wrong, its only that your ping is
> arriving at a higher rate than your contracted one.
> 
> If you want to manage the bandwidth so tightly you should look into
> traffic shaping on your customer's premises in order to match the
> contract you're offering.  
> 
> -----Original Message-----
> From: Kanagaraj Krishna [mailto:kanagaraj at aims.com.my] 
> Sent: Monday, September 26, 2005 8:03 AM
> To: Dan Martin
> Cc: cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] Re: Traffic Shaping packet loss
> 
> Dan,
>     I thought that the burst rate only takes into effect once the
> average 
> speed limit is passed. Am i right?
> 
> Quoting Dan Martin <dmartin at micromuse.com>:
> 
> > So many per unit time.
> > 
> > It doesn't wait a whole second and then pass or fail the stream.
> > 
> > It divides a second into some number of parts, figures out how many
> > packets or bytes should arrive during that part, and drops the rest.
> > 
> > That is why your burst setting fixes the problem.  You allow some
> number
> > of packets to arrive at a higher rate than contracted.
> > 
> > 
> > 
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net
> > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Kanagaraj
> > Krishna
> > Sent: Monday, September 26, 2005 6:26 AM
> > To: cisco-nsp at puck.nether.net
> > Subject: [c-nsp] Re: Traffic Shaping packet loss
> > 
> > Hi guys,
> >             I have a setup with a Catalyst 2950 connected to a GigE
> port
> > on 7206VXR. Sub-interfaces are configured on the GigE port for each
> VLAN
> > (dot1Q) that are assigned to each port in 2950. To control the
> traffic,
> > I've added the rate-limit command on the subinterface
> > 
> > rate-limit input 64000 2000 2000 conform-action transmit exceed-action
> > drop
> > rate-limit output 64000 2000 2000 conform-action transmit
> exceed-action
> > drop
> > 
> > It seems that when i do ping test, there are packet losses (even when
> > the traffic is low). One thing I realised is that when the burst rate
> is
> > increased, the packet loss decreases. Any idea on why this happens?
> > 
> > Regards,
> > Kana
> > _______________________________________________
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> > https://puck.nether.net/mailman/listinfo/cisco-nsp
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> > 
> 
> 
> -- 
> Kanagaraj Krishna
> Network Engineer
> Network Engineering
> Applied Information Management Services Sdn. Bhd.
> (AIMS Sdn. Bhd.)
> Ground Floor, Menara Aik Hua,
> Changkat Raja Chulan,
> 50200 Kuala Lumpur,Malaysia.
> 
> Tel     : +603-20314988 Ext : 395
> Mobile  :  012-3266151 
> Fax     : +603-20318948
> Email   : kanagaraj at aims.com.my
> 


-- 
Kanagaraj Krishna
Network Engineer
Network Engineering
Applied Information Management Services Sdn. Bhd.
(AIMS Sdn. Bhd.)
Ground Floor, Menara Aik Hua,
Changkat Raja Chulan,
50200 Kuala Lumpur,Malaysia.

Tel     : +603-20314988 Ext : 395
Mobile  :  012-3266151 
Fax     : +603-20318948
Email   : kanagaraj at aims.com.my