Switch to switch causing traffic problems?
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Posted by AnthonyL on April 19, 2005, 2:46 pm
Please log in for more thread options The arrangement is Office 1 - approx 12 PC's Switch 1 - router- internet | ~ 50 metres | Switch 2 Office 2 - approx 30 PC's plus 2 x Windows servers + 1 Novell 3.12 server (IPX) All Cat5e structured cabling. Virtually all traffic is from PC to one or other of the servers in Office 2. There are some networked printers in the system. Traffic load should be relatively low. One central database on SQL server on one server, Word Processing and Exchange on the other and a small DOS application serving 4 users in Office 1 on the Novell server. Some but not heavy internet access via Switch 1. Office 1 staff experience regular delays of sometimes up to a couple of minutes opening files or running an application. The link between the switches is 100mbit (as is the rest of the network except the 10mbit cards in the Novell server). There is a second cable running from Office 1 to Office 2 but that has not been connected and I'm not sure whether it is good practice to have a parallel run. One company has recommended to upgrade the link to a gigabit line but I find the logic hard to follow since the servers will still have 100mbit cards. Any helpful views welcomed. -- AnthonyL | |||||||||||||||||||
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Posted by Al Dykes on April 19, 2005, 11:03 am
Please log in for more thread options Did the switches cost less than $99 ? Do they run the latest software ? Is this a windows ActiveDirectry system ? If so, I think you have the wrong DNS entry in the PC that see long delays. You use the word "switch" and I suspect they are really routers. Are they all on the same subnet ? I imagine there could be other DNS/WINS problems. Does office 1 access the NW server ? I've seen problems when inexpensive equipment intended for cookie-cutter configurations get used in ways that are not shown in the manufacturer's glossy literature, as you are. I've been burned connecting a cheapo switch to a Big Name switch (Cisco in my case) and the Most Senior network engineer I know has taught me that doing switch-to-switch connections on the cheap is a No-No. He insists the the cheap end be a hub. FWIW. -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. | |||||||||||||||||||
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Posted by AnthonyL on April 20, 2005, 3:17 pm
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On 19 Apr 2005 08:03:30 -0400, adykes@panix.com (Al Dykes) wrote: >>The arrangement is
24 PORT 10/100MBPS Unmanaged switches
>> >>Office 1 - approx 12 PC's >> Switch 1 - router- internet PLANET SWITCH FNSW2400S >> |
>> ~ 50 metres >> | >> Switch 2 2 x 24 PORT 10/100MBPS Unmanaged switches Allied Telesyn AT-FS724I-30 >>Office 2 - approx 30 PC's plus
>> 2 x Windows servers + 1 Novell 3.12 server (IPX) >> >>All Cat5e structured cabling. >> >
> >Did the switches cost less than $99 ? 24 PORT 10/100MBPS Unmanaged switches PLANET SWITCH FNSW2400S Allied Telesyn AT-FS724I-30 >
>Do they run the latest software ? AFAIK there are no updates available >
Yes
>Is this a windows ActiveDirectry system ? >If so, I think you have the
Entries appear correct
>wrong DNS entry in the PC that see long delays. >
I think they are called switches. All on same subnet.
>You use the word "switch" and I suspect they are really routers. Are >they all on the same subnet ? >
Yes and in fact only office 1 accesses the NW server. No problems
>I imagine there could be other DNS/WINS problems. > >Does office 1 access the NW server ? with this. >
I don't understand I'm afraid what I am doing so wrong. Are you
>I've seen problems when inexpensive equipment intended for >cookie-cutter configurations get used in ways that are not shown in >the manufacturer's glossy literature, as you are. saying switch to switch is the wrong way to bridge the offices? >
>I've been burned connecting a cheapo switch to a Big Name switch >(Cisco in my case) and the Most Senior network engineer I know has >taught me that doing switch-to-switch connections on the cheap is a >No-No. He insists the the cheap end be a hub. FWIW. So I should replace the Planet switch with a hub? -- AnthonyL | |||||||||||||||||||
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Posted by J. Clarke on April 19, 2005, 11:19 am
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AnthonyL wrote: > The arrangement is
> > Office 1 - approx 12 PC's > Switch 1 - router- internet > | > ~ 50 metres > | > Switch 2 > Office 2 - approx 30 PC's plus > 2 x Windows servers + 1 Novell 3.12 server (IPX) > > All Cat5e structured cabling. > > Virtually all traffic is from PC to one or other of the servers in > Office 2. There are some networked printers in the system. > > Traffic load should be relatively low. One central database on SQL > server on one server, Word Processing and Exchange on the other and a > small DOS application serving 4 users in Office 1 on the Novell > server. Some but not heavy internet access via Switch 1. > > Office 1 staff experience regular delays of sometimes up to a couple > of minutes opening files or running an application. > > The link between the switches is 100mbit (as is the rest of the > network except the 10mbit cards in the Novell server). > > There is a second cable running from Office 1 to Office 2 but that has > not been connected and I'm not sure whether it is good practice to > have a parallel run. > > One company has recommended to upgrade the link to a gigabit line but > I find the logic hard to follow since the servers will still have > 100mbit cards. > > Any helpful views welcomed. The question is where the bottleneck lies. Cheap things to check. First, run virus, adware, and spyware scans on _everything_ for which you have a utility available. If you've got malware of some sort broadcasting tons of traffic on your LAN then nothing's going to work right until you fix that. Ping each computer from each other computer and see if there is unusual latency in either direction. Download a copy of qcheck <http://www.ixiacom.com/products/qcheck/>, install it on a Windows box,
read the readme, and download the appropriate endpoints from the link in
the readme, then see what speed you're really getting between machines and if you're getting the same speed both ways--if you're not then find out why--most common cause would be a configuration error--either speed or a duplex mismatch. Windows server includes a tool called "network monitor". Go into the Windows Server help and search on that and install it on your servers and then watch the traffic going to and from them and see if you're seeing anything coming in or going out that doesn't get a response. The free version only monitors traffic to and from the server on which it is installed, which is a significant limitation, but it's still a useful tool. There's a tool called "Ethereal" <http://www.ethereal.com/> which is a
general-purpose network analyzer similar in purpose to "network
monitor"--ethereal is a free download--install it on one of your machines that is experiencing the slowdown and watch the traffic and see if it's sending anything for which it is not getting a response or receiving anything to which it should be responding and isn't. With those tools and some time you should be able to identify most network problems--the trouble is that they're complex tools and it takes time to learn to use them--there's a book, "Ethereal Packet Sniffing" <http://www.amazon.com/exec/obidos/tg/detail/-/1932266828/qid=1113915990/sr=8-1/ref=pd_csp_1/104-1548119-3742340?v=glance&s=books&n=507846>
which may help. While you're about it, if you haven't already read them
try "Ethernet the Definitive Guide" by Charles Spurgeon <http://www.amazon.com/exec/obidos/tg/detail/-/1565926609/qid=1113916220/sr=1-1/ref=sr_1_1/104-1548119-3742340?v=glance&s=books>
and "TCP/IP Illustrated"
<http://www.amazon.com/exec/obidos/tg/detail/-/0201633469/qid=1113916303/sr=1-1/ref=sr_1_1/104-1548119-3742340?v=glance&s=books>.
If you don't already have managed switches (and if you did and knew how to use them you'd already know whether the link between them was the problem--they'll tell you statistics on it) you might want to consider picking up a couple of them off of ebay--Catalyst 2924s go for under $200 and sometimes under $100. I see Procurve 4000s, which for your use are serious overkill but a bit noisy, for about the same. -- --John to email, dial "usenet" and validate (was jclarke at eye bee em dot net) | |||||||||||||||||||
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Posted by Al Dykes on April 19, 2005, 1:20 pm
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>AnthonyL wrote:
> >> The arrangement is
>> >> Office 1 - approx 12 PC's >> Switch 1 - router- internet >> | >> ~ 50 metres >> | >> Switch 2 >> Office 2 - approx 30 PC's plus >> 2 x Windows servers + 1 Novell 3.12 server (IPX) >> >> All Cat5e structured cabling. >> >> Virtually all traffic is from PC to one or other of the servers in >> Office 2. There are some networked printers in the system. >> >> Traffic load should be relatively low. One central database on SQL >> server on one server, Word Processing and Exchange on the other and a >> small DOS application serving 4 users in Office 1 on the Novell >> server. Some but not heavy internet access via Switch 1. >> >> Office 1 staff experience regular delays of sometimes up to a couple >> of minutes opening files or running an application. >> >> The link between the switches is 100mbit (as is the rest of the >> network except the 10mbit cards in the Novell server). >> >> There is a second cable running from Office 1 to Office 2 but that has >> not been connected and I'm not sure whether it is good practice to >> have a parallel run. >> >> One company has recommended to upgrade the link to a gigabit line but >> I find the logic hard to follow since the servers will still have >> 100mbit cards. >> >> Any helpful views welcomed. >
>The question is where the bottleneck lies. > >Cheap things to check. > >First, run virus, adware, and spyware scans on _everything_ for which you >have a utility available. If you've got malware of some sort broadcasting >tons of traffic on your LAN then nothing's going to work right until you >fix that. > > Ping each computer from each other computer and see if there is unusual >latency in either direction. Download a copy of qcheck ><http://www.ixiacom.com/products/qcheck/>, install it on a Windows box, >read the readme, and download the appropriate endpoints from the link in >the readme, then see what speed you're really getting between machines and >if you're getting the same speed both ways--if you're not then find out >why--most common cause would be a configuration error--either speed or a >duplex mismatch. > >Windows server includes a tool called "network monitor". Go into the >Windows Server help and search on that and install it on your servers and >then watch the traffic going to and from them and see if you're seeing >anything coming in or going out that doesn't get a response. The free >version only monitors traffic to and from the server on which it is >installed, which is a significant limitation, but it's still a useful tool. > >There's a tool called "Ethereal" <http://www.ethereal.com/> which is a >general-purpose network analyzer similar in purpose to "network >monitor"--ethereal is a free download--install it on one of your machines >that is experiencing the slowdown and watch the traffic and see if it's If the OP has two switches then using a traffic monitor will be impossible unless the switches have management. If the switches have management then you'll get counters, which might show something interesting. Assuming dumb switches I think the blinkenlights are as useful. If the lights are not blinking he's got a problem with a timeout, not a high traffic problem. DNS problems would show up as the former. If you do have lots of blinking lights then the traffic monitor on a Windows box may tell you something but because you have a switch it can only see it's own traffic. ISTR that MS Monitor had software that could be installed at other points in the network and feed data back to the server for aggregation and analysis. That would solve the switch limitation. You can use perfmon.exe on any Windows box (except 98/me/dos) to analysis in great detail what it's doing. If your server (CPU and disk as shown by permon) is idle and the lights are not blinking then you do';t have a capacity problem, you've got a network design problem. IMO probably DNS. You can put ethereal on each and every box (except NW) and analysis the traffic and protocols. >If you don't already have managed switches (and if you did and knew how to
>use them you'd already know whether the link between them was the >problem--they'll tell you statistics on it) you might want to consider >picking up a couple of them off of ebay--Catalyst 2924s go for under $200 >and sometimes under $100. I see Procurve 4000s, which for your use are >serious overkill but a bit noisy, for about the same. > Agreed. Procurve boxes have a lifetime warranty so you can't go wrong. As for my issue with cheap/noname switch-to-switch connections, If you match brands, HP or Cisco you should be OK. -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. | |||||||||||||||||||
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>
>Office 1 - approx 12 PC's
> Switch 1 - router- internet
> |
> ~ 50 metres
> |
> Switch 2
>Office 2 - approx 30 PC's plus
> 2 x Windows servers + 1 Novell 3.12 server (IPX)
>
>All Cat5e structured cabling.
>
>Virtually all traffic is from PC to one or other of the servers in
>Office 2. There are some networked printers in the system.
>
>Traffic load should be relatively low. One central database on SQL
>server on one server, Word Processing and Exchange on the other and a
>small DOS application serving 4 users in Office 1 on the Novell
>server. Some but not heavy internet access via Switch 1.
>
>Office 1 staff experience regular delays of sometimes up to a couple
>of minutes opening files or running an application.
>
>The link between the switches is 100mbit (as is the rest of the
>network except the 10mbit cards in the Novell server).
>
>There is a second cable running from Office 1 to Office 2 but that has
>not been connected and I'm not sure whether it is good practice to
>have a parallel run.
>
>One company has recommended to upgrade the link to a gigabit line but
>I find the logic hard to follow since the servers will still have
>100mbit cards.
>
>Any helpful views welcomed.
>
>
>
>--
>AnthonyL