Re: Hubs/Switches

2000-09-18 Thread David Ross

  A autosensing hub has a built-in 2 port switch. Any 100Mbps ports are repeated
  together, as are the 10Mbps ports. The built in switch connects the 100Mb
  group to the 10Mb group.
 
 Which, by the way, creates an interesting problem when using a tool
 such as EtherPeek to record Ethernet packets.
 
 If EtherPeek is running on a CPU with a 10 MHz Ethernet connection,
 it will see all packets going between 10 MHz connections, but will
 *not* see any of the packets going from one 100 MHz to another 100 MHz
 connection because in effect these have been switched to a separate
 100 MHz "segment".  Very baffling until one figures out what is
 going on.

I had assumed it would be a bridge type connection, not a switch. I'll
bet both are out there. Thanks for the heads up.


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Re: Hubs/switches

2000-09-17 Thread Matt Barkdull

More clearing up...

Jim's description on how an auto-sensing hub works was excellent.

and here's some other thoughts.

The data transfer between any two devices will only happen at the 
speed of the slowest device.

So, a Mac talking to a switch at 100bps will talk to the switch at 
that speed, but if another Mac is only talking at 10bps, the two Macs 
will only talk to each other at 10bps.  The faster one will have a 
lot of wait cycles.

Now, there are two different technologies going into auto-sensing 
hubs though.  That is, a 10/100 Hub.  One, the backbone of the entire 
hub will communicate at the slowest speed (these are usually the very 
cheap 10/100 hubs), and the other that operates as two separate hubs 
joined together with a switch and therefore they will operate at the 
speed of the slowest device.  If both devices are 100bps, then the 
speed is 100bps, depending on load of the hub.I would wager that 
over 90% of the autosensing hubs use this method.




Some time ago there was a question on this list that concerned the 
use of a 10/100 switch or hub. There was a reply stating that a dual 
speed hub would only work at the speed of the slowest connected 
device. So a mix of 10 and 100 devices would cause all to run at 
only 10 mbps.

At the time I was dubious of this and have since looked into the 
question and while there may indeed be some hubs with this 
limitation, a modern autosensing dual speed hub will allow each 
device to run at its max speed, just as a switch will do, although 
without the other advantages of a switch of course, but they are 
cheaper.

Just thought I'd like to clear that up.



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Hubs/switches

2000-09-16 Thread Ken Gillett

Some time ago there was a question on this list that concerned the 
use of a 10/100 switch or hub. There was a reply stating that a dual 
speed hub would only work at the speed of the slowest connected 
device. So a mix of 10 and 100 devices would cause all to run at only 
10 mbps.

At the time I was dubious of this and have since looked into the 
question and while there may indeed be some hubs with this 
limitation, a modern autosensing dual speed hub will allow each 
device to run at its max speed, just as a switch will do, although 
without the other advantages of a switch of course, but they are 
cheaper.

Just thought I'd like to clear that up.


-- 



Ken  G i l l e t t


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Re: Hubs/switches

2000-09-16 Thread jakob krabbe



Thanx for your input. What exactleyt are you saying!?

We used to had that problem and it turned out that Mac OS was the failing
part. We bought a 24 port Intel 10/100 switch and Mac OS got all screwed
when it came to AppleTalking. I eventually solved it by putting a "software
beak" making 100 Mbit computers run at only 10 MBit.

This problem does not occur when choosing switches from D-Link! So I bought
a 24 port D-Link swich... (We're expanding and needed it anyway.) I haven't
made any research wethere the "breaked computers" would work at 100 MBit now.

We have bought loads of new computers lateley and the problem occured when
mixing commputers running at only 10 MBit like our ISDN Quadra 900. :-)

thanx,

/ jakob

(I hope this post make sence...)

At 09:41 2000-09-16 +0100, you wrote:
Some time ago there was a question on this list that concerned the 
use of a 10/100 switch or hub. There was a reply stating that a dual 
speed hub would only work at the speed of the slowest connected 
device. So a mix of 10 and 100 devices would cause all to run at only 
10 mbps.

At the time I was dubious of this and have since looked into the 
question and while there may indeed be some hubs with this 
limitation, a modern autosensing dual speed hub will allow each 
device to run at its max speed, just as a switch will do, although 
without the other advantages of a switch of course, but they are 
cheaper.

Just thought I'd like to clear that up.



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Re: Hubs/switches

2000-09-16 Thread Jim Grisham

A autosensing hub has a built-in 2 port switch. Any 100Mbps ports are repeated
together, as are the 10Mbps ports. The built in switch connects the 100Mb 
group to the 10Mb group.

Jim

jakob krabbe said, in a previous message:
 
 
 
 Thanx for your input. What exactleyt are you saying!?
 
 We used to had that problem and it turned out that Mac OS was the failing
 part. We bought a 24 port Intel 10/100 switch and Mac OS got all screwed
 when it came to AppleTalking. I eventually solved it by putting a "software
 beak" making 100 Mbit computers run at only 10 MBit.
 
 This problem does not occur when choosing switches from D-Link! So I bought
 a 24 port D-Link swich... (We're expanding and needed it anyway.) I haven't
 made any research wethere the "breaked computers" would work at 100 MBit now.
 
 We have bought loads of new computers lateley and the problem occured when
 mixing commputers running at only 10 MBit like our ISDN Quadra 900. :-)
 
 thanx,
 
 / jakob
 
 (I hope this post make sence...)
 
 At 09:41 2000-09-16 +0100, you wrote:
 Some time ago there was a question on this list that concerned the 
 use of a 10/100 switch or hub. There was a reply stating that a dual 
 speed hub would only work at the speed of the slowest connected 
 device. So a mix of 10 and 100 devices would cause all to run at only 
 10 mbps.
 
 At the time I was dubious of this and have since looked into the 
 question and while there may indeed be some hubs with this 
 limitation, a modern autosensing dual speed hub will allow each 
 device to run at its max speed, just as a switch will do, although 
 without the other advantages of a switch of course, but they are 
 cheaper.
 
 Just thought I'd like to clear that up.
 
 
 
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Re: Hubs/Switches

2000-09-16 Thread Garth Fletcher

Jim Grisham wrote:
 
 Subject: Re: Hubs/switches
 From: "Jim Grisham" [EMAIL PROTECTED]
 Date: Sat, 16 Sep 2000 10:55:38 -0500 (CDT)
 
 A autosensing hub has a built-in 2 port switch. Any 100Mbps ports are repeated
 together, as are the 10Mbps ports. The built in switch connects the 100Mb
 group to the 10Mb group.
 
 Jim

Which, by the way, creates an interesting problem when using a tool
such as EtherPeek to record Ethernet packets.

If EtherPeek is running on a CPU with a 10 MHz Ethernet connection,
it will see all packets going between 10 MHz connections, but will
*not* see any of the packets going from one 100 MHz to another 100 MHz
connection because in effect these have been switched to a separate 
100 MHz "segment".  Very baffling until one figures out what is
going on.
-- 
Garth Fletcher, President, JacqCAD International 
288 Marcel Road, Mason, NH 03048-4704
(603) 878-4749   fax: (603) 878-0547
JacqCAD MASTER website: www.JacqCAD.com




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