I am looking at applying the follwoing CAR config:
interface ATM2/0.1 point-to-point
description *****Connects To interface ATM5/0/0.11 On 7507 Bunker B*****
bandwidth 18000
ip address 19.46.189.2 255.255.255.252
rate-limit output access-group 102 13000000 9000 9000
\conform-action transmit exceed-action drop
What my questions are:
1. This will allow a sustained rate of 13Mb/s ?
2. I will be able to busrt a Max of 9000Bytes (72000Bits)
over the 13Mb/s. In practice will this give me a max
of a tiny bit over 13Mb/s. ?
3. How does the tokening system work if the user is only
running at 2Mb/s for an hour and suddenly bursts
to 40Mb/s do the tokens get kept for the hour ?
4. I note that Cisco have a formula:
normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds
extended burst = 2 * normal burst
Normal Burst= 13,000,000/ 8 * 1.5 = 2437500
Extended = 2437500 * 2 = 4875000
They recon for TCP traffic on average you will only achieve the
configured rate (in my example 13Mb/s). Based on the figures
above this seems like the customer could burst to 19.5Mb/s .
5. How do you calculate for how long and how often you can burst.
In my example can I burst to 19.5Mb/s for 1.5s every minute
every 1.5s*2 ??
6. Is there anything I should be weary of I dont really want the
customer bursting at all but I do not want a bad config to
affect there CIR ?
7. Is there any papers on the finer details of CAR ?
Thanks & Regards,
Kevin
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