bandwidth & data size relation

suthomas1 · ‎07-13-2009

Hi,

This query is to understand the relation between bandwidth throughput & data size.

Assuming we have a 2Mbps WAN(MPLS, serial,metroe)link.

No restriction is placed wrt to the data size ( viz. in MB/GB) that can be transferred over this link-my understanding.

So if this is correct, is there any relation between these two which we need to consider for bandwidth allocation or sizing?

If this is incorrect, please correct me.

Thanks.

Joseph W. Doherty · ‎07-13-2009

The simple relationship is bandwidth is bits per second (bps). Give a certain amount of data (size), bps will determine how long to make the transfer.

2 Mbps is 250 KB(ytes)ps. Data (payload) bandwidth is less. How much less depends on the media (there's media overhead) and frame/packet size overhead (which sets ratio between frame/packet overhead and payload [your data]).

For large frames/packets, your data might obtain 95%+ of "bandwidth". For minimum frames/packets you might effectively obtain less than 2% "bandwidth".

[edit]

BTW, there's even more to sizing, even for bulk data transfers. For instance, with something like MPLS or Metro Ethernet, a service provider shared bandwidth technology, there's bandwith to/from the provider backbone/cloud and what "bandwidth" you've contracted for through the provider backbone/cloud.

There's also many issues involved in how effectively your hosts can utilize the "bandwidth".