Slightly OT: Hub questions

[CSquared]

Kind folks,

I have a couple of questions if I may, mostly regarding a 6-port
Gigafast hub.

1. Does anyone know of any case where (or reason why) the hub would
refuse to forward packets with Class-A IP addresses while happily
forwarding those with Class-C addresses?

2. Is there usually any functional difference between the one upstream
port and the downstream ports on a hub?

FWIW, I have a TCP/IP puzzle of sorts which I actually believe is *not*
the fault of the hub at all, but rather some sort of issue with the
routing setup in a rather unique device I have feeding packets to
(hopefully through) the hub. The motivation for the questions is really
twofold: (1) to try and exonerate the hub more completely, and (2) to
try and expand my rather limited knowledge of TCP/IP a bit more.

Thanks for any input or comments,
Charlie C.
--
To email me, eradicate obfuscate & remove dot invalid.

[Char Jackson]

On Thu, 10 Jun 2010 20:14:54 -0500, CSquared
<obfuscate...@tx.rr.com.invalid> wrote:

>Kind folks,
>
>I have a couple of questions if I may, mostly regarding a 6-port
>Gigafast hub.
>
>1. Does anyone know of any case where (or reason why) the hub would
>refuse to forward packets with Class-A IP addresses while happily
>forwarding those with Class-C addresses?

I would expect a hub (or a switch, by the way) to be a Layer 2 device,
and therefore completely unaware of IP addresses, which reside at
Layer 3.

>2. Is there usually any functional difference between the one upstream
>port and the downstream ports on a hub?

Not that I've ever seen, other than some older equipment that required
a crossover cable for the uplink port. It's probably been 10 years
since I've seen a hub, though. Everything is switched these days.

>FWIW, I have a TCP/IP puzzle of sorts which I actually believe is *not*
>the fault of the hub at all, but rather some sort of issue with the
>routing setup in a rather unique device I have feeding packets to
>(hopefully through) the hub. The motivation for the questions is really
>twofold: (1) to try and exonerate the hub more completely, and (2) to
>try and expand my rather limited knowledge of TCP/IP a bit more.

Can you (even temporarily) replace the hub with a switch to verify
that the hub is working correctly?