Managed switches why and what

[Sl33py]

A software developer has suggested to my client that they get a managed switch to trouble shoot and manage their network. I am not familiar with managed switches. What can they do? What is a good option to go for (8 port unmanaged currently used) Do they come with the software?
What advantages do they have over unmanaged?

I read the en.wikipedia.org/wiki/Network_switch answer but I am still unclear
Thanks

 

[syntax]

Firstly, what issues are they having? How many users are there and what do they want to achieve? These questions will let u know what device/solution you are looking for.

As the wiki article probably explains, instead of just having a switch you plug into and thats it, a managed switch gives you more granular control and depending on the price/make model (Cisco for MW ) you can do some really cool things. From forcing port speeds (not much of an issue nowdays) to setting up VLANS, STP, using two ports for aggregation etc...

The switch comes with pre loaded management software which you will use a GUI interface to control. Command line access is also available on higher end switches but this is usually limited to performing more complex functions/ more granular settings.

But it comes back to the first part, why do you think you need it and what problems are u having?

 

[Conradl]

Also remember that you essentially get three types of switch - unmanaged, web/partially managed, and fully managed; depending on the features available. The above advice is good - first determine what you need to achieve from having a managed switch and then see if the features achieve the goal.

 

[Sl33py]

They use a DOS based invoicing and stock control program, the data gets corrupt and they think it might be a faulty network card or cable. There are 6 users and an ADSL router. Thanks

 

[TheGuy]

They are just looking for a switch that does port mirroring to capture the packets and see what's going on. If you can find an old hub it can do exactly the same thing.

 

[bekdik]

I think a free network sniffer would be more useful and cheaper

 

[Conradl]

Agree with the above, get a hub, plug all the machines into it, and use Wireshark in promiscuous mode to capture data. Cheaper and more effective....

 

[Sl33py]

Agree with the above, get a hub, plug all the machines into it, and use Wireshark in promiscuous mode to capture data. Cheaper and more effective....

I dont understand why a hub? I dont have one... What will I look for with Wireshark I have never used it and I am clueless regarding this whole process

 

[vangend]

I dont understand why a hub? I dont have one... What will I look for with Wireshark I have never used it and I am clueless regarding this whole process

Ask the software developer, seems like he is a networking expert. You might have problems getting your hands on a hub.

 

[syntax]

I dont understand why a hub? I dont have one... What will I look for with Wireshark I have never used it and I am clueless regarding this whole process

A hub can be used as a very cheap version of port spanning. IE the hub sends all data it receives out all ports.
How exactly is the data corrupt though? Does it get corrupt when it arrives on a certain share etc??? It could be disk issues rather than network problems.
However it cant hurt to check it out.

Wireshark will capture packets and allow you to see the whole process of communication at a very granular level. You will then be able to see things like sequence numbers, ports, data transferred etc.
I must admit, i think it highly unlikely that the data is being corrupted during the transmission. It is more likely to be OS/disk issues...

 

[Sl33py]

I am not sure how the data is corrupt..
I am going to sound like a idiot now. Ok so i will be able to look at the packets to see sequence numbers, ports, data transferred but how will I know when there is something wrong?
Will mention the OS / Disk issue to him

 

[gregmcc]

There's a much easier solution and free solution.

Take a large ISO (4GB) - get the MD5 checksum and then copy the file to and from various machines. Take the MD5 again, if its the same then there's no network corruption.

What protocol are they using in the app - TCPIP, netbeui (sp?)


I also highly doubt its a network problem - more like a OS or a application problem.

A network dump isn't going to help you much unless your a pro at reading network sniffs and understand network protocols.

 

[Sl33py]

They use TCP/IP

 

[gregmcc]

TCP is fairly rock solid and resilient and uses packet retransmissions for packets that are corrupt or are not received. Its highly improbably that its causing corruption. To prove it copy the large file above.

When did this corruption problem start? Were there any changes to the environment? Is the corruption problem repeatable. If you for example on have 2 machines on the network does it still occur?

 

[Sl33py]

One of the PC are not on the main UPS system, their power is not stable as it is in the rural areas. Then I am not sure if the Switches are on the UPS system so will test it tonight and see, maybe if the power dips they are getting a dropped connection. The one PC apparently freezes when they sometimes do receipting so will look into that (he mentioned that to me today). I think I will do the big file copy over the network sounds like a good plan.

We not sure when the coruption started, last year some time, the backups also had the errors

 

[s0lar]

Ask the software developer, seems like he is a networking expert. You might have problems getting your hands on a hub.

If you cant find a hub, try a linux box with two NICs in bridge mode. It transparent to the network and wont degrade it by making extra noise on the net. Check out ntop for a GUI overview of your analysis rather then decipher Wireshark's output.

 

[MidnightWizard]

Critical

Sounds like you may have a number of different issues from network cards to power supply and UPS.

You may have to go through a whole troubleshooting exercise checking all the different components.

Working with critical data really needs professional attention.

( A CISCO is only as good as the rest of the links in the chain -- but as I said -- IF it is critical data , then a R1000.00 PC and a R300.00 router are just asking for trouble )


MW

 

[ponder]

OMG I see a fsckup in the making

 

[Sl33py]

OMG I see a fsckup in the making

Well if you see it coming why dont you help?

Working with critical data really needs professional attention.

MW

Can you please explain what you mean by professional attention?

 

[MidnightWizard]

Helpful

Can you please explain what you mean by professional attention?

The services of someone with some sort of industry certification. ( Who can "guarantee" their work )


MW