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Dumb question - very little points.

Posted on 2002-07-12
Medium Priority
Last Modified: 2010-04-11
Take a network of 2 servers

1 - Windows 2000 - file/print and user management
2 - Windows 2000 SQL Server - database only

and 20 workstations of which 10 run an app that talks to the SQL server.

Network is TCP/IP and is hub-based (rather than co-ax).

With that setup ...

1 - Am I right in thinking that every packet will visit every machine on the network?

If yes, what decides the sequence of the "visits"?

Can the physical location of the servers make a difference to performance? i.e. which socket on the hub the servers are connected to?

Now add in a WAN link - with no filtering.

Would all the packets from both networks now visit every pc on both networks?

If so, what controls the sequence.

Now add filtering so that packets for THIS network do not go across the link to THAT network.

When a packet from THIS network is generated and DOES need to go across to THAT network, when it reaches the other side, will it visit all the pcs?


I've been asked to "speed" up the application. I'm a programmer, not a network specialist. Ideally, if it is just a case of some settings on what gets sent where, then I can probably manage that.

Windows networking with (as yet) an unknown link between 2 networks. No idea on what filtering orrouting is installed.

Ideas/suggestions/comments welcome.


Richard Quadling.
Question by:Richard Quadling
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LVL 40

Author Comment

by:Richard Quadling
ID: 7148709
The app is a Delphi app and uses the ODBC layer to talk to the SQL server. We use ODBC to support many different databses.

In all of our testing and our clients, the app takes a fraction of a second to display some of the more complex enquiry/lookup screens.

On a particular site, it takes well over 5 minutes.

I am about to visit the 2 sites and I am going to plug-in a notebook running the Ethereal software to see if information for the SQL server is reaching the other side of the WAN link.

In my mind, if it IS reaching this side it is going to have to visit every pc to decide whether or not it has been received.

I am a bit lost on what really happens as the data moves out of the source pc and how it gets to the destination pc.

Noddy language please.


LVL 31

Expert Comment

ID: 7148813
A hubbed network like a coax network will let all signals go to all stations simultaneously (disregarding propagation speed of electric signals). A speed/capacity benefit can be obtained by exchanging switches for hubs, as these will "learn" to which port a certain package is supposed to go (based on the NIC hardware address).

The link between two networks can be set up in various ways, with different results as to package distribution. What improvements that are possible here depends very much on the present setup.


Expert Comment

ID: 7148961
how do you add a wan link?
in order to add a wan link you should have a router?
can you talk a bit further about the topology of the network? then i can help you for all of your questions...
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LVL 40

Author Comment

by:Richard Quadling
ID: 7148999
I've not been to the customer's site.

What they are basically saying is our app is slow.

On their site it runs VERY slow.

Instead of fractions of seconds to get the results on the screen for a simple enquiry, it is taking well over 20 minutes!

What my intention was to see if data from the clients at site A, which is intended for site A SQL server only, is visible on the network at site B which are connected over a WAN. I suspect that there IS a router and it may not be configured properly.

If I don't get any packets from site A at site B then I have to look site A only. In this case, I would start with checking the SQL server for logs or even a stupid 3D screen-saver! You'd be surprised how often I've heard "our network is slow" - we visit, check the server and all is well for an hour or so and then "our server is slow" ...

In general, assuming no one is getting errors on the screen, what would be the effect of a workstation having the same IP address as the SQL server? Only the SQL server can handle the requests. Would this cause significant delays? I know the server should be using DHCP, but I never installed it and I've been told to fix it!

Are any of you guys in Leeds in England and want a quick fix?
LVL 31

Expert Comment

ID: 7149023
Hehe, sorry: Stockholm, Sweden. Not that I'd mind a visit to the UK, though...
LVL 31

Expert Comment

ID: 7149094
I have been managing a hubbed+coax net for a while now, and my input here would be to recommend the following:

1) Make sure the two LAN:s are each set up properly. That includes IP addressing (DHCP or static), DNS service or any other host name resolution scheme, as well as checking for any computers having individual problems with network access.

2) LAN-LAN connection can be achieved in several different ways. If you could tell us how this is done in this case, some suggestions for improvement are bound to crop up.

LVL 79

Accepted Solution

lrmoore earned 400 total points
ID: 7149100
>1 - Am I right in thinking that every packet will visit every machine on the network?

No. Only broadcast packets are sent to every machine. A PC query to the SQL server is a single conversation.

>Now add in a WAN link - with no filtering.
Would all the packets from both networks now visit every pc on both networks?

Absolutely not. A WAN link requires a router. A router, by design will not even propogate broadcasts. However, you can setup a bridge where you can send all broadcasts across and have a single flat network. Or filters, or... many options.

>When a packet from THIS network is generated and DOES need to go across to THAT network, when it reaches the other side, will it visit all the pcs?

No. It will only be sent directly to the MAC address that is assigned the IP address of the destination.

Does the ODBC connector use named pipes or TCP/IP?

LVL 40

Author Comment

by:Richard Quadling
ID: 7149107
I've just been told that we are not going to site after all. They have been finding all sorts of leaks/bad setup with their installation.

We only supplied 1 app for their system. It is a client based app linked to their SQL server. They had another company do all the networking and WAN links.

It seems we suggested they look at the router and firewall log files. I think they found something.


Grade B as there was not really a question to have answered.

Thanks for the time.
LVL 40

Author Comment

by:Richard Quadling
ID: 7149114
I think it was named-pipes and they moved it to TCP/IP.

So. Upgrade to Grade A as you did answer my question after all!

LVL 79

Expert Comment

ID: 7149225
Sometimes it's the little things that make a big impact...

Glad to help!

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