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Message started by EDWIN on Aug 22nd, 2007 at 5:03pm

Title: CIR/EIR
Post by EDWIN on Aug 22nd, 2007 at 5:03pm
please, I want to difference between CIR/EIR/Burst Priority/Queue Size and their relationships.
At site which am supposed to have 64kbps dedicated, and am having cirtohub 34 and  maxbwtohub  68, is this a dedicated or sheared  service? please, i want to know.

Title: Re: CIR/EIR
Post by pgannon on Aug 28th, 2007 at 3:38pm
Are you sure you don't mean BIR?

Never heard of EIR.

CIR is committed information rate - which is dedicated bandwidth.  

BIR is burstable information rate - which is shared bandwidth.

Some network operators mislead customers with CIR, using it to mean continuous information rate, instead of committed information rate.  The first is an average and is not dedicated bandwidth; the second is a committed minimum amount of dedicated bandwidth.  

However CIR is sometimes oversubscribed which technically means it really isn't CIR anyway as it can't be guaranteed.  Let the buyer beware.

Burst priority and Queue size refer to bandwidth management or QoS (quality of service) options.  Burst priority determines what traffic goes first.  Queue size determines how much traffic needs to be queued up before it's sent.  With data, for example you want to queue up a big chunk before sending it.  With VoIP (voice over IP), you want to send the small voice packets immediately, because the longer you hold them in a queue the more jitter you create.  Jitter kills voice quality.  

These terms could refer to specific types of traffic (data, voice, etc.) or they could refer to how your specific site accesses the service in relation to all the other sites.  In other words, sites with a higher burst priority would get to transmit before sites with a lower priority.  This could be the basis for several different classes of service.  

I'm not familiar with the specific terms your system configuration uses.  I would interpret cirtohub as 34 Kbps of CIR (dedicated) bandwidth on your upload link.  I would interpret maxbwtohub as 68 Kbps of BIR.  If this is correct, you have a shared upload service of 68 Kbps upload, with half of it dedicated (assuming the CIR is not oversubscribed by the network operator).  These parameters do not appear to describe your download capacity as data generally flows from the hub to the remote (download or outroute) and remote to hub (upload or inroute).

What VSAT service are you using?  Where are you finding these parameters?


Title: Re: CIR/EIR
Post by pgannon on Aug 28th, 2007 at 5:16pm
Found it on the web...

EIR (excess information rate) is a Bandwidth Profile parameter. It defines the average rate in bits/s of ingress Service Frames up to which the network may deliver Service Frames without any performance objectives.

That's more or less the same thing as BIR.  

It says you "might" get it, not that you "will" get it.

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