Wireshark · Ethereal-users: RE: [Ethereal-users] Others' Traffic.. no HTTP?

[Richard Urwin <RUrwin@xxxxxxxxxxxxxxx>]

I think all 10/100 hubs use a switch between speeds. All the ones I've come
acros do. My laptop has a 10Meg combo card in it, so I've seen this in the
field. I had to pull one end of the conversation down to 10Meg.

Theoretically, a 10/100 switch could be used to buffer the old card up to
100Meg. I haven't tried it though. These things are now cheap enough to make
it reasonable to carry one around.


+--------------+   10     +--------------+         
| 10M Ethereal |----------| 10/100 'Hub' |
+--------------+          +--------------+
                                 |
                                 |100
                                 |         
                     +-----------------------+
                     | Existing 10/100 'Hub' |-------------->100M
conversation
                     +-----------------------+

-----Original Message-----From: Bob Foxworth
[mailto:bfoxworth@xxxxxxxxxxxxxxxx]
Sent: 14 November 2001 14:54
To: Guy Harris; Rob Stidman
Cc: Bob Foxworth; ethereal-users@xxxxxxxxxxxx
Subject: RE: [Ethereal-users] Others' Traffic.. no HTTP?


	The original post by me referred to a situation where two devices
	using Realtek 8139 chip NICs were connected through a Linksys
	"EtherFast 10/100 Auto Sensing 8port Workgroup Hub" model
	EFAH08W. These were exchanging legal UDP frames. I believe
	the NICs had autonegotiated to 100 Mbit.

	In order to check the traffic we then connected an old DOS-based
	analyzer using a 16bit ISA-bus SMC 8416 NIC running a DOS based
	commercial analyzer product (from 1996). We could see
	miscellaneous background traffic from other stations (ARP
	requests and NetBios broadcasts) which led me to believe
	the device was acting a a switch. We could not see the desired
	UDP traffic.

	When we connected the 2 test machines and the analyzer to
	an old 4-port 10Mbit only Netgear hub, we got the desired
	traffic. So this may be an issue of the "hub" being a switch,
	rather than a speed negotiation issue, since the 10 Mbit
	anlyzer was seeing other stations on the network broadcasting,
	and I think everything here is now using 10/100 NICs except for
	the old analyzer we tried. 

	One reason I like the DOS based analyzers, or Linux based is
	that they don't do any of their own broadcasting. Windows-based
	analyzers do send out NetBIOS which gets in the way. My old
	analyzer doesn't support PCI based interrupts, so doesn't see
	much use anymore since it won't take a 10/100 card. Suppose I
	could try a different analyzer but the immediate need has passed
	(verified the traffic flow).

	Bob F

> On Tue, Nov 13, 2001 at 05:51:17PM -0500, Rob Stidman wrote:
> > My problem also involved a Linksys hub acting the same way, and I solved
> my
> > problem, also, with a netgear.
> 
> Hmm.  Linksys claim on their Web site that their hubs really are hubs:
> 
> 	http://www.linksys.com/support/support.asp?spid=7
> 
> which sayd
> 
> 	Switch VS. Hub.  All Linksys Switches provide for Full-Duplex
> 	speed and cut down the traffic on the network by sending the
> 	packets only to the port on the workstation is to receive the
> 	information.  The Linksys hubs only operate at Half-Duplex speed
> 	and they broad cast a packet to all the nodes on the network...
> 
> However, that paragraph goes on to say:
> 
> 	...(the Auto- sensing hubs broadcast the 10Mb packets to the port
> 	that operate at 10Mb only and broadcast the 100Mb packets to the
> 	ports that operate at 100Mb only.
> 
> Was this (and the hub in the other example) an auto-sensing hub, with
> the sniffing done on a port with a different speed from the other ports?
> Or is the Linksys Web site making an incorrect claim (which I could
> believe is the case, given that a Google search for "Linksys switching
> hub" found references to the "Linksys Switching Hub EZXS16W" and to the
> EZXS55W switching hub, although the Linksys site refers to the EZXS16W
> and EZXS55W as switches)?
> 
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