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Community Member

LAN Capacity

I am doing an analysis on the network and have the following question:

Assume that an average SNMP response message is 100 bytes long. Assume that a manager sends 40 SNMP “get” commands each second. What percentage of a 100Mbps LAN link's capacity would the resulting response traffic represent?

Thanks in advance,

sK

6 REPLIES
Hall of Fame Super Silver

Re: LAN Capacity

Hello Sadik,

I would use the following calculation:

100 byte IP packet takes 18 byte ethernet overhead

+

20 byte of "silence" inter frame gap

40 * 138 * 8 bps = 44160 bps

0,4% of BW of a 100 Mbps link

Hope to help

Giuseppe

Community Member

Re: LAN Capacity

Thank you Giuseppe for the quick response. I am not clear on how you get the 4%?

Also, since the 44160 is in bps don't you have to convert the 100Mbps to bps to get the bps percentage out of the 100Mbps?

Thanks,

sK

Hall of Fame Super Silver

Re: LAN Capacity

Hello Sadik,

sorry I was meaning 0.04 % in my country we use , instead of . for decimal separation

take 44160 bps

44160 / 100 10^6 = 0,0004416

to express a percentage you need to multiply by 100

so you get 0.04%

Edit:

(I had also made an error dividing by 10^7 instead of 10^8)

I hope you got the process ..

Hope to help

Giuseppe

Community Member

Re: LAN Capacity

Ok... Now it is clear!

Thanks again Giuseppe.

SK

Community Member

Re: LAN Capacity

May I ask why is the multiplication by 8bps in the equatation:

40 * 138 * 8 bps = 44160 bps

Hall of Fame Super Silver

Re: LAN Capacity

Hello Vladimir,

the 8 is for 8 bit/byte the packet size is expressed in bytes (100 byte ip plus the other overheads )

Hope to help

Giuseppe

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