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timeouts because of  a hub

Posted on 2001-07-18
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Last Modified: 2008-02-26
im in a subnet, in it we have two routers, one connects to a rdis (128) and the other to frame relay.
i have three hubs cascade(all are unmanaged).
my server as solaris whith informix aplications.
the problem:
the users connect to server normaly but only last about five minutes are disconnect by a timeout of 10seconds.
i changed one user from that hub to another and he is working fine.
the dmi/dmix is correct.
question:
what can i do to see if the problem is really the hub or something else.
and are there tools for win95 to see if the hub is working fine(all ports in the hub).

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Question by:numazupt
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20 Comments
 

Author Comment

by:numazupt
ID: 6293443
forgot about something, there is some static energy near the hubs
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Expert Comment

by:jwalsh88
ID: 6293726
Well what kind of Hubs are they?  Are they Class II repeaters or above?  Are they Fast Ethernet (10/100Mbps)  If they are fast ethernet you have too many hubs.  Either way I would say that your configuration of 3 hubs is wrong and thats whats causing your issues.
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Expert Comment

by:vsamtani
ID: 6293884
I agree with jwalsh above - three cascaded hubs is asking for trouble. If they're unmanaged hubs, then there is no way to get any diagnostics on the hubs without methodically testing each port one after the other. The static energy certainly won't help, and you may find that you need (a) to replace at least one of the hubs with a switch, and (b) cage the hardware to reduce its exposure to the static, and perhaps use STP cable where it runs through electrically noisy areas.

Vijay
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Author Comment

by:numazupt
ID: 6294674
i have 3com superstack II(dual speed 24) and two officeconnect dual speed 8. connected in cascade.
1 hub- officeconnect
2 hub- officeconnect
3 hub- 3com superstack II

Ethernet network
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Expert Comment

by:jwalsh88
ID: 6294700
That would be your problem.  you can never use 3 100 Mbps Hubs together.  You will have intermittent problems until you seperate those hubs with a switch.
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Author Comment

by:numazupt
ID: 6294885
i have 3com superstack II(dual speed 24) and two officeconnect dual speed 8. connected in cascade.
1 hub- officeconnect
2 hub- officeconnect
3 hub- 3com superstack II

Ethernet network
0
 
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Expert Comment

by:jwalsh88
ID: 6294901
okay but you still need to break up those hubs with a switch.
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Author Comment

by:numazupt
ID: 6294904
i have consulted 3com and they told me that isn't a problem, the only thing that maybe is causing th failure is the cable that connects the hubs can not be longer than 50cm and that should be cat5 preferebly stp. And that static energy could cause the problem also. but they told me that tree hubs connected are not a problem.
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Expert Comment

by:jwalsh88
ID: 6295153
Well if we are talking hubs not switches by design using Fast Ethernet on CAT5 your entire run from source to destination can not be longer then 200 meters, you can only have 2 Class II Repeaters in between.  Otherwise the respnse from one end points is too long and they can't detect signals fast enough to avoid collisions.  It doesn't really matter what 3com says thats just how fast ethernet over copper works.
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Author Comment

by:numazupt
ID: 6295605
yes thats is correct jwalsh88.
so you advice me to put a switch in between hubs, but then i would creat segment in the network, isn't this correct?
it will be like if i had two hubs (one hub= the two office/the second= the dualstack) i think.
And i dont want that i want to maintain th tree hubs as one.
what do you advice
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Author Comment

by:numazupt
ID: 6295632
yes thats is correct jwalsh88.
so you advice me to put a switch in between hubs, but then i would creat segment in the network, isn't this correct?
it will be like if i had two hubs (one hub= the two office/the second= the dualstack) i think.
And i dont want that i want to maintain th tree hubs as one.
what do you advice
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Author Comment

by:numazupt
ID: 6295663
yes thats is correct jwalsh88.
so you advice me to put a switch in between hubs, but then i would creat segment in the network, isn't this correct?
it will be like if i had two hubs (one hub= the two office/the second= the dualstack) i think.
And i dont want that i want to maintain th tree hubs as one.
what do you advice
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Expert Comment

by:jwalsh88
ID: 6296100
I don't really see what you are getting at but while this will segment your network, logically it will still be exactly the same.  YOu don't have one hub, you have 3 hubs.  you will still have 3 hubs.

I just realized since you weren't very descriptive I have no idea how your 3 hubs are connected together.  Some hubs can be connected with special cables but most are connected with ethernet cables.  How are yours connected?  Because if they are connected together with special daisy chain style cables you might be able to use more then 2 but I don't think so.
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Author Comment

by:numazupt
ID: 6303386
first i ask for forgiveness because it seems that i am experiencing some trouble when i post (it apears two or three postings)


they are connected whith ethernet cable.
what is strange is that i today put dmi/dmix to dmi and then put back to the original position and the problem desapeared.
if you have an email jwalsh88 i will send to you a map of the network(made in visio)

thank you all
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Expert Comment

by:jwalsh88
ID: 6303444
jwalsh88@flash.net
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Accepted Solution

by:
jwalsh88 earned 300 total points
ID: 6308000
I am sure the problem did not disappear, the problem is not a definite one, it will be intermittent.  How the problem works is if you have a station connected to this "cluster" of hubs, and it is set at 100Mbps then it needs to be able to get a response from all other workstations in a certain amount of time.  It is stated that the response time needed is impossible to achieve with three hubs regardless of distance.  Now if that response time can't be achieved then you will have lots of collision problems since one station sends and the 100Mbps station is to far to know it before he sends.  then you have a collision.  Now any station set at 10Mbps wont have as many issues except when a station set to 100Mbps stomps on his transmission.  So, I would recommend either getting a very small switch to put in between two of the hubs or setting all devices on the network to 10Mbps speed and half duplex.  Either will solve your too many hubs problem.
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Author Comment

by:numazupt
ID: 6308289
if th hubs are unmanaged, i can only change in the users nic to work at 10. Correct me if i'm wrong.
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Expert Comment

by:jwalsh88
ID: 6308341
You are correct.
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Author Comment

by:numazupt
ID: 6308578
maintaining my hardware that's the only solution that you see jwash88.
or there is another.

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Author Comment

by:numazupt
ID: 6309490
thank you jwalsh88
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