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 From:  "Don Munyak" <don dot munyak at gmail dot com>
 To:  m0n0wall at lists dot m0n0 dot ch
 Subject:  Taffic Shapping Question
 Date:  Thu, 29 Jun 2006 10:21:02 -0400
Taffic Shapping Question

This may be a bit off topic, but I'm a little confused and/or don't
understand. In the proposal were are considering for a co-lo facility,
the vendor has made the following two statements about the measureable
bandwidth plan. I've read it a hundred times and still don't quite
understand HOW-to interpret.

{snip...}

Half Cabinet
- Industry standard 21 RU w/ 19" W x 28" D x 36" H usable space.
- (1) CAT 6 Ethernet data connections (upgradeable to gigabit Ethernet)
- (1) DSO/DS1 connections
- (1) Single 100Mbps Ethernet drop

Bandwidth Rate Plan: Single 100Mbps Ethernet drop with data transfer
measured at 95th percentile of maximum transfer rate per month.
Commitment is 1.0 Mbps, overage charged at $30.00 per 0.1Mbps.

Internet Bandwidth: single 100 Mbps Ethernet connection, 1 Mbps
commitment on burstable 95th percentile billing.

1) Burstable Bandwidth measured in Mbps using 95th percentile calculation.
Burstable Front Channel connectivity bandwidth subscription levels are
in increments of 1 Mbps. The minimum bandwidth subscription levels per
rack are as follows:

Cabinet or Shared Cage | Half-Rack (8 Amps Max) | 0.5 Mbps
Cabinet or Shared Cage | Full-Rack (16 Amps Max) | 1.0 Mbps

95th Percentile Burstable Bandwidth Measurement calculation:
bayMountain collects the number of bits (in both octets in and octets
out) in 5-minute intervals. The number of bits is then divided by 300
seconds (5 minutes x 60 seconds) to derive one Inbound sample and one
Outbound sample. The total monthly sample size will then be sorted in
descending order (from largest to smallest) in two separate groups
(Inbound and Outbound). The top 5% of the sample size (roughly 432 of
the top ranked samples) is removed. The next highest sample after the
removal of top 5% is the 95th percentile sustained usage level for the
month. The highest 95th percentile sample between the Inbound and
Outbound samples is considered the sustained usage level for billing
purposes. Overages to be billed in 0.1 Mbps increments.

{...snip}

With respect to m0n0wall, is this saying (using an arbitary number) if
I have paid for a 512k feed burstable to 768k, but I keep exceeding
768k, I'm going to get charged overage ? If so, I should consider
using traffic shapper to limit burstable / sustained traffic ??

Also....Would someone please translate the "Burstable Bandwidth"
explanation into laymans terms. Maybe providing an example.

TIA,

~Don