[AusNOG] Contention, congestion, and link capacity planning

[Ahad Aboss]

Hi Paul,

When it comes to backhaul capacity planning for business grade customers,
there is no one size fit all formula. It all comes down to the type of
customers you have and the frequency of internet usage during business hrs
and after hrs.

Generally, the peak usage for business customer is between 8am – 6pm, MON -
FRI. You’ll need to have enough backhaul capacity at the head-end to cater
for occasional burst during peak hrs though not all customers download at
full speed all at once.This is just for safety measures.

For Ethernet or midband Ethernet services through Optus, TPG/AAPT or
Telstra, you could get away with 3:1 contention on the backhaul but I
strongly recommend that you don’t risk this contention ratio if you have
less than 100 customers per state.

Let’s say you have 100 customers, a combination of 50 x 10Mbps and 50 x
20Mbps, you can safely use 1Gbps backhaul per state through a single
provider (AAPT/Telstra or Optus) and as you add more customers, you can
closely watch the average usage across the customer base and increase the
bandwidth as required.

Just to be clear, the 3:1 contention is for best effort Ethernet services
ONLY which is mostly used by SMEs, if you are providing guaranteed
bandwidth 1:1, you will have to honour the contention all the way to your
POP and internet.

If you are building up your customer base slowly, be prepared for very slim
or no margins at all as you still need to pay for the access links to
customers, trunk port (head end or backhaul), IP transit, rack space, power
and cross connect fees.

In these circumstances, it’s best to resell these services through a
reliable ISP until your Ethernet customer base is sizeable to justify the
head end built.

For residential grade broadband factor in 50% traffic growth every year, a
blessing that all ISPs have to deal with while trying to maintain their
profit margin. :)

Based on industry contacts, the current average usage per SIO (IN AUS) for
NBN and DSL are as follows;

NBN: 1.3Mbps

xDSL: 850Kbps

Netflix and HD/UHD video streaming is changing the peak average rapidly.

I hope this information helps.

Cheers,

Ahad

On Mon, Sep 18, 2017 at 12:41 PM, paul+ausnog at oxygennetworks.com.au <
paul+ausnog at oxygennetworks.com.au> wrote:

> Hi All, I was hoping to gain some thoughts from the list around contention
> and backhaul link capacity planning.
>
>
>
> We are working on some new site plans and have plenty of existing sites to
> draw usage statistics from when it comes to capacity planning, typically
> all of our backhaul links are running pretty low contention as all of our
> customers are business customers, but I am wondering if anybody has any
> formulas they have used successfully in the past.
>
>
>
> Being that we only provide business Ethernet connections planning is
> usually pretty straight forward, but in modelling some expansion plans I
> want to try and actually wrap something around the planning process for
> backhaul capacity.
>
>
>
> For example, 1 x 50M customer will clearly need 50M of backhaul from the
> POP they connect to, but what about 2, or 4, or 10 ?
>
> You could easily surmise that 2 x 50M customers don’t need 100M of
> backhaul unless they are very heavy users, so let’s say they may need 75M,
> but this requirement for backhaul is realistically a sliding scale as the
> customers and bandwidth requirements grow the backhaul is not necessarily
> going to need to grow at the same rate.
>
>
>
> I have worked this stuff out for some time now manually and had good
> results, our customers are happy, but I was hoping there would be some sort
> of calculation or formula that I could apply to some modelling figures
> which would give me a pretty close indication of requirements.
>
>
>
> Thanks in advance
>
>
>
> Regards
>
> Paul
>
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>
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