Re: How to measure how many bandwidth used in the network via ne

Adam David · ‎02-09-2012

Hi,

I’m planning to install a brand new Cisco firewall as follows.

Current Design

Switch A ------ Switch B

Proposed Design

Switch A --- New Firewall --- Switch B

In order to determine which model, I need to know how many traffic/bandwidth on the network. As example, if the bandwidth used in the network is about 150 - 300 Mbps, then we can use ASA 5510. But if more bandwidth used, then higher model is needed such as ASA 5520 (Maximum firewall throughput 450 Mbps).

http://www.cisco.com/en/US/products/ps6120/prod_models_comparison.html#~mid-range

Someone told me this can be done by “sh int” command on the switch, but I’m not sure the right way to do it/to read the output.

As example, output of sh int below shows that the bandwidth is 10000 Kbit. Is this the one that I should look for?

Router# show interfaces

Ethernet 0 is up, line protocol is up

Hardware is MCI Ethernet, address is 0000.0c00.750c (bia 0000.0c00.750c)

Internet address is 10.108.28.8, subnet mask is 255.255.255.0

MTU 1500 bytes, BW 10000 Kbit, DLY 100000 usec, rely 255/255, load 1/255

Encapsulation ARPA, loopback not set, keepalive set (10 sec)

ARP type: ARPA, ARP Timeout 4:00:00

Last input 0:00:00, output 0:00:00, output hang never

Last clearing of "show interface" counters 0:00:00

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

Five minute input rate 0 bits/sec, 0 packets/sec

Five minute output rate 2000 bits/sec, 4 packets/sec

1127576 packets input, 447251251 bytes, 0 no buffer

Received 354125 broadcasts, 0 runts, 0 giants, 57186* throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

5332142 packets output, 496316039 bytes, 0 underruns

0 output errors, 432 collisions, 0 interface resets, 0 restart.

http://www.cisco.com/en/US/docs/ios/12_3/interface/command/reference/int_s3g.html#wp1138804

Please let me know if you need more info. Thanks in advance.

andrew.prince · ‎02-09-2012

Http://cacti.net

Sent from Cisco Technical Support iPad App

Adam David · ‎02-10-2012

Thanks Andrew for your prompt reply. Cacti require some configuration/installation. Is it possible to use available command on the Cisco Switch without using any 3^rd party monitoring tool?

Vivek Ganapathi · ‎02-10-2012

Hello Adam,

Depends on the cisco model you are using. You can try netflow, below a video for you to see.

www.youtube.com/watch?v=KujLCfW2V8w

Thanks

Vivek

Antony Peiris · ‎04-18-2016

Hi Vivek,

I think on your formula one Zero is missing from 100,000,000. I believe this should be 1000000000. Reason is, as you mentioned above

1 Gbps = 100,000,000,0 bps

If we do this in a different way on your interface output

3000 bits per seconds in kbps = 3kbps

3000 bits per seconds in kbps = 4kbps

3 + 4 = 7kbps

1G = 1000000kbps ( MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec)

formula

7/1000000 x 100 = 0.0007%

Please correct me if I am wrong

Vivek Ganapathi · ‎02-10-2012

You can configure MRTG / Cacti / Solarwinds bandwidth monitor. MRTG & Cacti are freewares, solarwinds has a 30 day trial version. My suggestion would be solarwinds.

Thanks

Vivek

Adam David · ‎02-10-2012

Thanks Vivek, I really appreciate it. However, these solutions are not for me as I don’t have a write access to the switches & can’t configure additional tools on the network. But I do have read access to the switches and use any available command on it.

I did a quick google on this issue and found similar solution here.

How to Check Bandwidth usage on router ?

http://answers.yahoo.com/question/index?qid=20070910043818AAaS2Lr

So, I’ve performed “sh int Gi0/1” in 5 minutes interval and have the following outputs.

sh clock	7:47	7:52
sh int Gi0/1	... 5 minute input rate 3000 bits/sec, 3 packets/sec 5 minute output rate 4000 bits/sec, 4 packets/sec 1754961 packets input, 383416613 bytes, 0 no buffer Received 515250 broadcasts (152537 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 515250 multicast, 0 pause input 0 input packets with dribble condition detected 1835485 packets output, 295200516 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 0 output buffer failures, 0 output buffers swapped out	... 5 minute input rate 2000 bits/sec, 3 packets/sec 5 minute output rate 3000 bits/sec, 3 packets/sec 1755859 packets input, 383580756 bytes, 0 no buffer Received 515457 broadcasts (152599 IP multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 515457 multicast, 0 pause input 0 input packets with dribble condition detected 1836470 packets output, 295363529 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 0 output buffer failures, 0 output buffers swapped out

Quick comparisons between these two outputs are as below. Can I determine how much bandwidth used in the network based on this info? Please advise.

ITEMS	BEFORE	AFTER 5 MINUTES	DIFFERENCE
5 minute input rate	3000	2000	-1000
5 minute output rate	4000	3000	-1000
packets input	1754961	1755859	898
bytes	383416613	383580756	164143
broadcasts	515250	515457	207
multicasts	152537	152599	62
packets output	1835485	1836470	985
bytes	295200516	295363529	163013

Vivek Ganapathi · ‎02-10-2012

The formula to calculate utilization is

Utilization (U) Percentage = (Throughput/Data Rate) x 100

For example as below

5 minute input rate 3000 bits/sec,

5 minute output rate 4000 bits/sec,

Utilization Percentage (input) = (3000 / 100,000,000) x 100 = ?

Utilization Percentage (output) = (4000 / 100,000,000) x 100 = ?

Utilization Percentage (total) = [(3000 + 4000) / 100,000,000] x 100 = ?

I was too lazy enuff to calculate the stuff But that's the formula you can use. Those input/output rate is based on your screenshots.

Hope this helps.

Thanks

Vivek

Adam David · ‎02-10-2012

Thanks Vivek for the info. I’ve learned something new today

And don’t worry about the calculation as there is a reason why spreadsheet as excel or calculator is created.

Here is the answer for that. But I was wondering where do you get the value of “100,000,000”

Utilization Percentage (input)	0.003
Utilization Percentage (output)	0.004
Utilization Percentage (total)	0.007

Vivek Ganapathi · ‎02-10-2012

Thanks for that But i need to seriously learn to calculate lol..

Have a great time.

Thanks

Vivek

Adam David · ‎02-10-2012

Utilization (U) Percentage = (Throughput/Data Rate) x 100

Ah, I’ve overlooked the formula given above. Does it mean value of “Data Rate” is always 100,000,000?

I’ve just discussed about this matter with my friend and he said “input rate” is enough to determine the bandwidth used in the network. So, obviously Cisco ASA 5505 is just nice as it can support up to 150 Mbps throughput while the throughput on the network just 3000 bits/sec. Is that true?

Cisco ASA 5500 Series Model/License	Cisco ASA 5505 Base / Security Plus	Cisco ASA 5510 Base / Security Plus	Cisco ASA 5520	Cisco ASA 5540	Cisco ASA 5550
Product Image (click to enlarge)
Network Location	Small Business, Branch Office, Enterprise Teleworker	Internet Edge	Internet Edge	Internet Edge	Internet Edge, Campus
Performance Summary
Maximum Firewall throughput	150 Mbps	300 Mbps	450 Mbps	650 Mbps	1.2 Gbps

http://www.cisco.com/en/US/products/ps6120/prod_models_comparison.html#~mid-range

Michael Kiessling · ‎02-10-2012

Hi,

maybe I missed that, but what kind of switches are we talking about (at least what kind of ports)?

If you use the 'show interface' command and read the 5min rates over the busiest times (for each 10 minutes or so)

you should at least get a feeling about your bandwitdth requirement.

Regards,

Michael

Vivek Ganapathi · ‎02-10-2012

No, your data rate is dependent upon the interface you have. That one was for Fastethernet interface.

100 Mbps = 100,000,000 bps

1 Gbps = 100,000,000,0 bps

You need to consider capturing the utilization during your peak usage hours which will provide you an idea of average traffic you receive on the interface.

AFAIK, to measure the throughput you need to consider input/output rate as it's bidirectional. Don't get confused with speed & throughput, they are two different things. Maximum firewall throughput isn't speed of the interface. What that says is a maximum traffic of 150Mbps could be handled by the firewall (which is actually from inside & from outside).

Hope i tried clarifying.

Thanks

Vivek

How to measure how many bandwidth used in the network via network switch?