| Author |
Message |
Ken Mandelberg
Guest
|
 Posted:
Wed Mar 16, 2005 5:15 am Post subject:
Need Ethernet Hub - NOT Switch |
|
|
I'm looking for a simple unmanaged 16 port rack mountable 100mbit
ethernet hub, which is NOT a switch.
We bought a Linksys EF2H16 because it was advertised as a hub, but after
monitoring it found it acting as a switch. Linksys tech support after
lots of probing told me that the older versions were in fact just hubs
but they had silently substituted newer silicon that acted as a switch
in the current version.
Can anyone suggest a product that will do what I want?
--
Ken Mandelberg | km@mathcs.emory.edu
Emory University |
Dept of Math and CS | Phone: Voice (404) 727-7963
Atlanta, GA 30322 | FAX (404) 727-5611 |
|
| Back to top |
|
 |
sqrfolkdnc
Guest
|
| Posted:
Wed Mar 16, 2005 8:02 am Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
can you go in and set the cache so small it will always overflow?
According to another thread here, most switches become hubs when the
cache fills up.... |
|
| Back to top |
|
|
Arnold Nipper
Guest
|
| Posted:
Wed Mar 16, 2005 1:20 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
On 16.03.2005 04:15 sqrfolkdnc wrote
| Quote: | can you go in and set the cache so small it will always overflow?
According to another thread here, most switches become hubs when the
cache fills up....
|
Note: but only for the "excess" traffic. I.e. for traffic to MAC
destinations not in the cam table (cache).
I would have a look at eBay where you can get relative new 24-port hubs
for small money (<=20$). e.g.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11181&item=5757509295&rd=1
Arnold
--
Arnold Nipper, AN45 |
|
| Back to top |
|
|
Petri Krohn
Guest
|
| Posted:
Wed Mar 16, 2005 2:43 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
"Ken Mandelberg" <km@mathcs.emory.edu> kirjoitti viestissä
news:d17tro$s20@mathsunf.mathcs.emory.edu...
| Quote: | I'm looking for a simple unmanaged 16 port rack mountable 100mbit
ethernet hub, which is NOT a switch.
|
WHY would you want to use a hub, not a switch?
I can imagine you could use a small hub to monitor traffic, maybe in some
lab or test environment, but why 16 ports and a fixed installation?
--
Petri Krohn
Helsinki Neighborhood Networking Association
HelsinkiOpen -- http://www.helsinkiopen.net |
|
| Back to top |
|
|
Walter Roberson
Guest
|
| Posted:
Wed Mar 16, 2005 3:29 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
In article <d18v25$17qm$1@news.bbnetworks.net>,
Petri Krohn <petri.krohn@iki.fi-n-l-a-n-d.invalid> wrote:
:"Ken Mandelberg" <km@mathcs.emory.edu> kirjoitti viestissä
:news:d17tro$s20@mathsunf.mathcs.emory.edu...
:> I'm looking for a simple unmanaged 16 port rack mountable 100mbit
:> ethernet hub, which is NOT a switch.
:WHY would you want to use a hub, not a switch?
:I can imagine you could use a small hub to monitor traffic, maybe in some
:lab or test environment, but why 16 ports and a fixed installation?
Perhaps he needs to monitor a number of devices.
Perhaps (considering his university email address) he needs it for
teaching purposes, so a number of students can all get copies of the
packets.
Perhaps he needs to connect devices that have difficulty with
autonegotiation .
Perhaps he needs to connect a number of devices that need layer 2
frames that are not passed through switches, such as CDP (Cisco
Discovery Protocol) or Cisco PIX LAN failover keep-alives.
--
History is a pile of debris -- Laurie Anderson |
|
| Back to top |
|
|
Ken Mandelberg
Guest
|
| Posted:
Wed Mar 16, 2005 3:41 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
Thanks for all the responses.
As to why we don't want a switch:
We already have a large rack mounted mesh of switches. The hub was to
consoldiate a collection of wireless access points onto one of the
switch ports. Because of mobility issues we didn't want to deal with
any issue of the switch having to relearn port association when a
wireless session flipped between access points. It would also be a plus
to be able to monitor from any of the hub ports.
We used the Linksys EF2H16 "hub" for a while thinking it was as advertised
not a switch. Mostly it worked fine, even when laptops moved between access
points. However, sometimes it didn't. In some cases we saw a laptop able
to broadcast its dhcp request all the way through to the dhcp server, but
unable to get its unicast reply. The "hub" was confused about what port to
send the reply to, and this persisted for hours.
That example might just indicate a poor Linksys implementation, or even a
defective piece of hardware. I was really only expecting a few second of
trouble on port switching. Still it seems to me a real hub is what we want.
If we wanted a switch we could connect directly to ports on our managed
switches and not need a hub at all.
Ebay references:
Thanks also for the ebay pointers on older hubs. I might go this way, though
my preference would be to get a new/warranteed piece of hardware if such a
thing exists.
--
Ken Mandelberg | km@mathcs.emory.edu
Emory University |
Dept of Math and CS | Phone: Voice (404) 727-7963
Atlanta, GA 30322 | FAX 727-5611 |
|
| Back to top |
|
|
J. Clarke
Guest
|
| Posted:
Wed Mar 16, 2005 5:49 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
Arnold Nipper wrote:
| Quote: | On 16.03.2005 04:15 sqrfolkdnc wrote
can you go in and set the cache so small it will always overflow?
According to another thread here, most switches become hubs when the
cache fills up....
Note: but only for the "excess" traffic. I.e. for traffic to MAC
destinations not in the cam table (cache).
I would have a look at eBay where you can get relative new 24-port hubs
for small money (<=20$). e.g.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11181&item=5757509295&rd=1 |
The problem is that most "relative new 24-port hubs" are implemented using
switch chips because it's cheaper to do it that way than to wire up a hub
with discrete devices.
What he needs is an _old_ hub, made when it was still expensive to make a
switch.
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11181&item=5760215738&rd=1&ssPageName=WDVW>
might be a good bet. 100TX only though, not dual-speed, if that's a
problem.
Somebody needs to make a list of "real" vs "imitation" hubs.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
|
| Back to top |
|
|
Geir Gulbrandsen
Guest
|
| Posted:
Wed Mar 16, 2005 6:29 pm Post subject:
Re: Need Ethernet Hub - NOT Switch (Slightly off topic) |
|
|
On Wed, 16 Mar 2005 10:29:30 +0000, Walter Roberson wrote:
| Quote: | Perhaps he needs to connect a number of devices that need layer 2
frames that are not passed through switches, such as CDP (Cisco
Discovery Protocol) or Cisco PIX LAN failover keep-alives.
|
CDP would only be filtered by Cisco switches, wouldn't it?
I believe the DST of a CDP frame is 01:00:0C:CC:CC:CC, and that this
should be treated as a regular MC frame by devices not implementing the
proprietary CDP. |
|
| Back to top |
|
|
Alan J. Flavell
Guest
|
| Posted:
Wed Mar 16, 2005 8:02 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
On Wed, 16 Mar 2005, J. Clarke wrote:
| Quote: | 100TX only though, not dual-speed, if that's a problem.
|
No offence meant, but surely there can be no such thing, literally, as
a "dual-speed hub"? There are/were some boxes which contain, in
effect, a 10M hub and a 100M hub, interconnected by a switch. They
used to be marketed as "dual speed hubs", but technically we knew what
that really meant. |
|
| Back to top |
|
|
Al Dykes
Guest
|
| Posted:
Wed Mar 16, 2005 8:36 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
In article <d19aoh0ghi@news3.newsguy.com>,
J. Clarke <jclarke.usenet@snet.net.invalid> wrote:
| Quote: | Arnold Nipper wrote:
On 16.03.2005 04:15 sqrfolkdnc wrote
can you go in and set the cache so small it will always overflow?
According to another thread here, most switches become hubs when the
cache fills up....
Note: but only for the "excess" traffic. I.e. for traffic to MAC
destinations not in the cam table (cache).
I would have a look at eBay where you can get relative new 24-port hubs
for small money (<=20$). e.g.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11181&item=5757509295&rd=1
The problem is that most "relative new 24-port hubs" are implemented using
switch chips because it's cheaper to do it that way than to wire up a hub
with discrete devices.
What he needs is an _old_ hub, made when it was still expensive to make a
switch.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11181&item=5760215738&rd=1&ssPageName=WDVW
might be a good bet. 100TX only though, not dual-speed, if that's a
problem.
Somebody needs to make a list of "real" vs "imitation" hubs.
Arnold
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
|
If you buy a used box made by Cisco/3Com/HP you can trust that if it
says it's a hub, it's a hub.
before buying you should get the model # and grap the manual from the
manufacturer's web site and read up to make sure you know what youi
are buying. I wouldn't trust a seller to describe the item correctly.
HP has a lifetime warranty on some of it's gear. Hard to go wrong.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
|
| Back to top |
|
|
Al Dykes
Guest
|
| Posted:
Wed Mar 16, 2005 8:40 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
In article <Pine.LNX.4.61.0503161457220.20522@ppepc56.ph.gla.ac.uk>,
Alan J. Flavell <flavell@ph.gla.ac.uk> wrote:
| Quote: | On Wed, 16 Mar 2005, J. Clarke wrote:
100TX only though, not dual-speed, if that's a problem.
No offence meant, but surely there can be no such thing, literally, as
a "dual-speed hub"? There are/were some boxes which contain, in
effect, a 10M hub and a 100M hub, interconnected by a switch. They
used to be marketed as "dual speed hubs", but technically we knew what
that really meant.
|
Right idea, but I beleive that it's a bridge that connects the two
sides and I expect that the chip used is much faster than the 10Mb
side can either source or sink bits and so it's effectivly invisible.
A basic bridge passes all traffic.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
|
| Back to top |
|
|
Al Dykes
Guest
|
| Posted:
Wed Mar 16, 2005 9:08 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
In article <d19k3p$qje$1@finch.mathcs.emory.edu>,
Ken Mandelberg <km@mathcs.emory.edu> wrote:
| Quote: | Thanks for all the responses.
As to why we don't want a switch:
We already have a large rack mounted mesh of switches. The hub was to
consoldiate a collection of wireless access points onto one of the
switch ports. Because of mobility issues we didn't want to deal with
any issue of the switch having to relearn port association when a
wireless session flipped between access points. It would also be a plus
to be able to monitor from any of the hub ports.
We used the Linksys EF2H16 "hub" for a while thinking it was as advertised
not a switch. Mostly it worked fine, even when laptops moved between access
points. However, sometimes it didn't. In some cases we saw a laptop able
to broadcast its dhcp request all the way through to the dhcp server, but
unable to get its unicast reply. The "hub" was confused about what port to
send the reply to, and this persisted for hours.
That example might just indicate a poor Linksys implementation, or even a
defective piece of hardware. I was really only expecting a few second of
trouble on port switching. Still it seems to me a real hub is what we want.
If we wanted a switch we could connect directly to ports on our managed
switches and not need a hub at all.
Ebay references:
Thanks also for the ebay pointers on older hubs. I might go this way, though
my preference would be to get a new/warranteed piece of hardware if such a
thing exists.
|
I believe the HP Procurve line has a lifetime warranty. If you're
worring about warranty coverage buy two or three on ebay and keep them
for spares. I see Cisco 24 port 10/100 hubs are going for as little
as $40 on ebay.
--
a d y k e s @ p a n i x . c o m
Don't blame me. I voted for Gore. |
|
| Back to top |
|
|
Hansang Bae
Guest
|
| Posted:
Wed Mar 16, 2005 11:04 pm Post subject:
Re: Need Ethernet Hub - NOT Switch (Slightly off topic) |
|
|
Geir Gulbrandsen wrote:
| Quote: | CDP would only be filtered by Cisco switches, wouldn't it?
I believe the DST of a CDP frame is 01:00:0C:CC:CC:CC, and that this
should be treated as a regular MC frame by devices not implementing
the proprietary CDP.
|
Only Cisco and (some) HP switches eat cdp frames. Other switches
happily pass it along.
--
hsb
"Somehow I imagined this experience would be more rewarding" Calvin
**************************ROT13 MY ADDRESS*************************
Due to the volume of email that I receive, I may not not be able to
reply to emails sent to my account. Please post a followup instead.
******************************************************************** |
|
| Back to top |
|
|
John Rowe
Guest
|
| Posted:
Wed Mar 16, 2005 11:16 pm Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
Ken, at the risk of stating the obvious, you're at a University, can
you not just email your networking colleagues explaining your problem
and asking if anybody can swap a hub for a switch? I have two 16 port
hubs sitting in a cupboard, surely there must be loads in Emory.
And if you can't get a 16-port hub you should be able to daisy-chain
two 8-porters together.
John |
|
| Back to top |
|
|
J. Clarke
Guest
|
| Posted:
Thu Mar 17, 2005 12:12 am Post subject:
Re: Need Ethernet Hub - NOT Switch |
|
|
Alan J. Flavell wrote:
| Quote: | On Wed, 16 Mar 2005, J. Clarke wrote:
100TX only though, not dual-speed, if that's a problem.
No offence meant, but surely there can be no such thing, literally, as
a "dual-speed hub"? There are/were some boxes which contain, in
effect, a 10M hub and a 100M hub, interconnected by a switch. They
used to be marketed as "dual speed hubs", but technically we knew what
that really meant.
|
A dual speed hub used to be two repeaters linked by a single bridge.
I mentioned that mainly to save clicking the link if he needs 10baseT.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net) |
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in