Autosensing in Dual Speed hubs?

Hi,
Do Dual speed hubs sense for the speed of the connected links
just once when the link is connected or repeatedly as long as
they are connected?

Thanks in advance.

Thanks,
Senthil.

When they are connected the link speed is determined and set.

--
Dave




"C.G.Senthilkumar." <(E-Mail Removed)> wrote in message
news:ct472s$lkl$(E-Mail Removed)...
| Hi,
| Do Dual speed hubs sense for the speed of the connected links
| just once when the link is connected or repeatedly as long as
| they are connected?
|
| Thanks in advance.
|
| Thanks,
| Senthil.
|
|

Thanks for the reply.

I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
One is newer (and hence more powerful) than the other.

I used netperf[1] to transfer 4 different TCP streams of data of
various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
both directions one after the other. The maximum throughput I could
get was only around 90 Mbps when the more powerful machine was the
sender and around 70Mbps in the other direction.

Why am I not getting near 100Mbps throughput? Is there something
else going on in the Hub? I don't have any other network applications
running on the either of the computers.

Thanks in advance.

Senthil.

Ref:
[1] netperf - a network performance evaluation tool from HP.

That's a maximum that is rarely obtained. On a hub you are on a shared segment. Only ONE
platform can transmit at a time and has to wait until there are no sending nodes and then it
will send. Then it must get acknowledgement packets. This is governed by CSMA/CD - Carrier
Sense with Multiple Access/Collision Detection. Then you have to take into account the
protocol being used, yada, yada... Then there is the OS overhead, chip-sets, LAN cards,
etc...

Don't worry, be happy 70~90Mb/s is good performance.

I see you are at a University. Take a course on Networking.

--
Dave




"C.G.Senthilkumar." <(E-Mail Removed)> wrote in message
news:ct6cgi$nnh$(E-Mail Removed)...
| Thanks for the reply.
|
| I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
| One is newer (and hence more powerful) than the other.
|
| I used netperf[1] to transfer 4 different TCP streams of data of
| various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
| both directions one after the other. The maximum throughput I could
| get was only around 90 Mbps when the more powerful machine was the
| sender and around 70Mbps in the other direction.
|
| Why am I not getting near 100Mbps throughput? Is there something
| else going on in the Hub? I don't have any other network applications
| running on the either of the computers.
|
| Thanks in advance.
|
| Senthil.
|
| Ref:
| [1] netperf - a network performance evaluation tool from HP.

"David H. Lipman" <DLipman~nospam~@Verizon.Net> wrote in message
news:sTyJd.28188$Os6.25468@trnddc08...
> That's a maximum that is rarely obtained. On a hub you are on a shared
segment. Only ONE
> platform can transmit at a time and has to wait until there are no sending
nodes and then it
> will send. Then it must get acknowledgement packets. This is governed by
CSMA/CD - Carrier
> Sense with Multiple Access/Collision Detection. Then you have to take
into account the
> protocol being used, yada, yada... Then there is the OS overhead,
chip-sets, LAN cards,
> etc...
>
> Don't worry, be happy 70~90Mb/s is good performance.
>
> I see you are at a University. Take a course on Networking.
>
> --
> Dave
>
>
>
>
> "C.G.Senthilkumar." <(E-Mail Removed)> wrote in message
> news:ct6cgi$nnh$(E-Mail Removed)...
> | Thanks for the reply.
> |
> | I have 2 Linux boxes connected to a NetGear DS106 10/100Mbps hub.
> | One is newer (and hence more powerful) than the other.
> |
> | I used netperf[1] to transfer 4 different TCP streams of data of
> | various sizes (from 2 MB to 2 GB) between the 2 Linux boxes in
> | both directions one after the other. The maximum throughput I could
> | get was only around 90 Mbps when the more powerful machine was the
> | sender and around 70Mbps in the other direction.
> |
> | Why am I not getting near 100Mbps throughput? Is there something
> | else going on in the Hub? I don't have any other network applications
> | running on the either of the computers.
> |
> | Thanks in advance.
> |
> | Senthil.
> |
> | Ref:
> | [1] netperf - a network performance evaluation tool from HP.

If you want to see anything close to line speed, the first step would be to
eliminate the hub and install a small, inexpensive switch.

Actually an expensive Ethernet switch. Cheap switches have high latency ratings. Quality,
managed, switches have a lower latency.

--
Dave




"Drew Peacock" <(E-Mail Removed)> wrote in message
news:s7OdneXZqZxQwpffRVn-(E-Mail Removed)...

|
| If you want to see anything close to line speed, the first step would be to
| eliminate the hub and install a small, inexpensive switch.
|
|