Burst configuration question

I have set sustained uplink and downlink to 768kb in my canopy.

What effect will setting uplink and downlink burst allocation have? For example. If I set it to 0 will the customer simply have 768kb available to them with no bursting? Or should I set burst to match the sustained or does this allow an extra 768kb of burst. (1.5mb total)?

Lastly, how long does a burst last and can I change the burst ‘time’ allocation as well?

Thanks in advance.

Found my answer in a copy of the manual from 2004 that stated on page 23 in the pdf. Set the burst equal to sustained to cancel burst. Setting burst below sustained will limit the sustained the the burst amount. (so setting burst to 0 and sustained to 768 would mean throughput is 0).

A link with 768 sustained and 256 burst would give a potential total of 1mb.

jamesy wrote:
(so setting burst to 0 and sustained to 768 would mean throughput is 0).

Nope, it just means you have no burst. Sustained @ 768 means that it should not dip below that number.

A link with 768 sustained and 256 burst would give a potential total of 1mb.

Not necessarily. Keep in mind that burst is measured in kbits. A burst of 256kbits means that your SM will run at its max speed, assuming the burst bucket on the AP is not emptied, until it reaches 32KB of data. Your customer would be hard pressed to even notice a difference.

hmmm. I went by the following:

Pages 22-23 of the motorola canopy sm manual:

4.2.4 Interaction of Burst Data and Sustained Data Settings
A Burst Allocation setting
• less than the Sustained Data Rate yields a Sustained Data Rate equal to the Burst Allocation. (See Figure 5 and Figure 7.)
• equal to the Sustained Data Rate negates the burst capability. (See Figure 6.)
• at zero shuts off the data pipe. (See Figure 8.)

Then went looking in the canopy 8 release user guide. pg 55 in the pdf (Grabbed it on Motorola’s site and didn’t see one for V9)

7.1.10 Interaction of Burst Allocation and Sustained Data Rate Settings
If the Burst Allocation is set to 1200 kb and the Sustained Data Rate is set to 128 kbps, a
data burst of 1000 kb is transmitted at full speed because the Burst Allocation is set high
enough. After the burst, the bucket experiences a significant refill at the Sustained Data
Rate. This configuration uses the advantage of the settable Burst Allocation.
If both the Burst Allocation and the Sustained Data Rate are set to 128 kb, a burst is
limited to the Burst Allocation value. This configuration does not take advantage of the
settable Burst Allocation.
If the Burst Allocation is set to 128 kb and the Sustained Data Rate is set to 256 kbps, the
actual rate will be the burst allocation (but in kbps). As above, this configuration does not
take advantage of the settable Burst Allocation

So you are saying that I have 768kb sustained plus 768kbps burst for a total of around 1.5mb ? I guess I’m not understanding the documentation and I confess I’m new at this.

I cannot speak for the really old Canopy s/w, but any HW scheduling SM with the burst @ 0 does not shut off the data pipe. I can only assume that it is referring to the burst data pipe. I’ve tested a P10 5.7 SM running 9.5 s/w with d/l & u/l burst @ 0 and the SM will reach sustained speeds only. With the burst @ 128k I still experience sustained speeds.

Heres how it was explained to me and through bench testing seems to be accurate. Burst size is a file size, not a speed. If set to 128k than the first 128k of data runs at full unrestricted bandwidth. after 128k it will throttle to the sustained rate until the bucket is full again. Then it repeats. We set ours at 2000k. This allows web sites to load very quickly, but downloads throttle to sustained rates.

page 86 of the canopy 8 user guide.

◦ the burst allocation affects how many kilobits are processed before packet delay is imposed.
◦ the sustained data rate affects the packet delay that is imposed.

Let me share the example configured on our network.

We sell 2000k 10:1 for soho. We make the 10:1 with linux servers and htb but also on the radios we configure:
sustained up: 500
sustained down: 1000
burst up: 8000
burst down: 8000

When a user runs a speedtest on a single pc he gets 2000kbps down and around 1000kbps up.
But when he makes one big download(or several small ones) he only gets 1000kbs down.

Moinavery, could you explain in more detail how you handle the 10:1 with linux and htb (not sure what htb is)?

Its a linux software with you can set CIR and MIR. You can have a 2048kbps pipe with n smallers pipes in it.
The smaller pipe is the CIR, every user wil have at least that.
The big pipe(2048k this case) is the MIR. If only 1 user is online he will get the full 2048k, if another user comes online the server will split the 2048 among them and so on…


Ok thanks I’ll look into it.
How many users can it handle?

We have around 300 users with shared bandwith running on a HP ML115 with 2 Giga of ram. The aplication uses many ram.
Again its one layer of control, the other layer runs on Prizm.

In some cities that we dont have vlan1 We only use the prizm