question about estimating the congesed BW in Router

[Dr.X]

hi ,

assume i have aern isp , and the rout that is connetced to internet is called R1

note that R1 is connected  another router to get the internet traffic which is R2 and after R2 is the could internet .

assume the topology is

>>>local network>===========<R1>==========<< purchased BW>>==========>R2>=============cloud internet

as we know , that the BW is estimated  between me "R1" and R2 the  internet router .

assume i bought a 200 Mega BW from R2 , 

i have not QOS on R1 , so sometimes my LINK which is 200 Mega is full

and im using SNMP to see my traffic which is full and only to 200 Mega

MY Questin is :

how to estimate the reall bw that need to go internet and was reduced to 200 , i mean  assume the users mad a traffiic 250 Mega , then

only 200 from 250 Mega will go internet and about 50 mega will be congesed " actually i dont know the behaviuor on my router when there is more bw  "

i mean how to know that there were 50 Mega need to be bought from Internet router   ???

knowing the congesed traffic will help me about   additional BW i need to purchase it from  the ISP R2 .

wt commands i can use it from router to estimate that bw.

regards

Ahmad

[AhmedSonba]

Hello Ahmed,

You will need first to set the load inervale for the interfaces on your router that is connected to the Internet

with the following commands

Under the interface issue the following

load-interval 20

then use

show interface  " interface type and slot "  | inc drops|bits

and check the bandwidth used and if there is drops in the packets on the interface

It will look something like this

show interface fastethernet  0/4 | inc drops|bits

  Input queue: 0/4096/0/0 (size/max/drops/flushes); Total output drops: 0

  30 second input rate 1970000 bits/sec, 3120 packets/sec

  30 second output rate 1616000 bits/sec, 2582 packets/sec

     0 unknown protocol drops

How it will help

Ahmed Sonba

[Dr.X]

hi ahmed ,

actually i didnt understand u well ,

my intrface is giga ethernet and preconfigured with loadinterval  30

i did as u suggested and here is the output :

Input queue: 0/75/53/0 (size/max/drops/flushes); Total output drops: 14075

  Queueing strategy: fifo

  Output queue: 0/40 (size/max)

there are drops above , but how to estimate  the additinal bw i need ???

regards

[AhmedSonba]

Hello Ahmed,

The above I was just showing an example , of course you will use what type of interface you have , anyhow your output shows that you have Output dropswhich  typically shows that you have a congested interface

To solve it you either can do Congestion management to ensures that important packets are always forwarded,  while less important packets are dropped when the link is congested. or you add more bandwidth I would advice you to run some sort of monitoring program on you router via SMTP . I use PRTG program on my network and from there you can monitor you network and gather some statistics and then  can estimate how much bandwidth you will need.

Hope it will help

Ahmed Sonba

[Dr.X]

hi , im also using prtg monitor snmp ,

i can only get bw on my interfaces but dont know the required bw i need to add

have u an y suggests ?

regards

[AhmedSonba]

Hello Ahmed,

Good you are already on the right way, you need to check for example  the bandwidth for the past week or so to see if most of the time you see that your bandwidth usage is taking up all the 200 Mb that you have that means for sure that you will need to upgrade your bandwidth.

Hope it will help

Ahmed Sonba

[Dr.X]

hi ahmed ,

knowing bw is congesed is not problem

but my problem is how much bw i need to add , this is just my issue ,

now , my bw is full , so  wt amount i need to add ?

10 mega ? or 20 mega or 30 mega ???

regards

[AhmedSonba]

Hello Ahmed,

You need to calculate how much traffic your users are using and what application they are using and that time you will have an idea of how much you need to add.

for example you are using Voip on your network than you need to calculate how many calls you are making

each one use 35 Kb  if was G729  than number of concurrent calls  * 35Kb and you can get an idea how much bandwidth you will need .

Hope it will Help

Ahmed Sonba