HO to DR bandwidth

[adamgibs7]

Dears,

I have been given a task to decide the bandwidth from HO to DR,,  the bandwidth is decided on basis of what ?? everyday in GB's  ( around 10 to 15 GB) traffic will be passed from HO to DR, so how i shld calculate the bandwidth requirement so that i can ask ISP for the same. is it been calculated on type of traffic or on amount of data ( like in GB's)

Thanks

[Georg Pauwen]

Hello,

10-15GB in what amount of time ? During a normal business day (9 to 5) ?

[adamgibs7]

this is for the schedule backup and that will be in the night,

[Joseph W. Doherty]

For a scheduled backup, you find the amount of bytes you need to move within what timeframe, and then allow for overhead and other traffic. That will reveal the amount of bandwidth you need.

[adamgibs7]

Dear Joseph

Can you do a simple match for explanation , so that it will be clear understanding.

thanks

[Joseph W. Doherty]

Sure.

Let's assume you need to backup 100 GBytes. That's 800 gigabits. If your time window was 8 hours, you would need to move 100 gigabits an hour, payload, or (divide by 3600) (about) 28 Mbps. Considering L2 and L3 overhead, and, if using TCP, TCP's typical sawtooth transmission rate, add about 25%. So, you would need a link that could provide (about) 35 Mbps for 8 hours.

[adamgibs7]

Dear Joseph,

Let's assume you need to backup 100 GBytes. That's 800 gigabits. If your time window was 8 hours, you would need to move 100 gigabits an hour

I understood the above math's but

I didn't understood this math's --->payload, or (divide by 3600) (about) 28 Mbps 

can u elaborate more in 2 scenarios how we can calculate bandwidth and the another scenario to how calculate time if we have the know bandwidth.

thanks

[Georg Pauwen]

Hello,

on a side note, you can use the bandwidth/time calculator linked below...

http://wintelguy.com/wanperf.pl

[Joseph W. Doherty]

Ok, if you understand 100 gigabits an hour, what that's per second?

There are 60 minutes per hour and 60 seconds per minuted, 60 * 60 = 3600.

If you know the bandwidth, you can calculate the inverse. Say you have 10 Mbps. That 1.25 MB(ytes)s or 75 MB in a minute or 4.5 GB an hour.

If I haven't addressed your question(s), let me know.

[adamgibs7]

Dear Joseph

U r super bronze but not me so please bare with me I really still didn't understood your math's. I am not able to do the inverse can u help me with simple math's as what I described below if we aware of the bandwidth.

I have put the math's here where in case I know the bandwidth (50Mb/s) and I get the answers in seconds which further we divide by 60  for min and further by 60 to get hrs. but what abt if we know the seconds and we have to calculate bandwidth ??

• 4.5 GB is about 4600 MB (4.5 x 1024). 4600 MB is about 36800 Mbit (4600 x 8)

In a best case scenario, it would then take 736 seconds (36800 Mbit / 50 Mbit/s) to download the file. so the file will be downloaded in 12 mins

[Joseph W. Doherty · Accepted solution]

" 4.5 GB is about 4600 MB (4.5 x 1024). 4600 MB is about 36800 Mbit (4600 x 8)

In a best case scenario, it would then take 736 seconds (36800 Mbit / 50 Mbit/s) to download the file. so the file will be downloaded in 12 mins"

I calculate the same, although again remember you need to allow for L2 and L3 and L4 overheads, so I would add about 25% to your 12 minutes.

" have put the math's here where in case I know the bandwidth (50Mb/s) and I get the answers in seconds which further we divide by 60 for min and further by 60 to get hrs. but what abt if we know the seconds and we have to calculate bandwidth ??"

Okay, taking your example, what if we need to move your 4.5 GB in two minutes? As you noted, you have 36,800 Mbit to move, but again in two minutes. Two minutes is 120 seconds, so if we divide 36,800 by 120, that will gives us (about) 307 Mbps.