Internet speed drop when connecting a Cisco Business 250 Series Smart switch to an netgear unmanaged switch

[john19251]

When connecting Cisco Business 250 Smart switch to existing network internet speed tests dramatically drops over 50%.

What can be causing this issue. Keep in mind this is when the switch is connected to another unmanaged Netgear switch. Also this is using default configurations. 

Please help!

[Seb Rupik]

Hi there,

How is the Cisco switch being connected to the netgaer, one or two links. what is there configuration? Can you share the config of the cisco switch, indicating which interfaces are connected to the netgaer.

Regarding the slow internet speeds. From what device is this observed? One connected to the netgear throughout? One moved onto the cisco switch?

cheers,

Seb.

[john19251]

Hello Seb,

To answer your questions.

1. The cisco switch is connected via a cat 5e cable to one ethernet port on the switch. So it would only be one link. 

2. I need to find my console to usb dongle so I wont be able to get you the command line config. But here is the

graphic that indicates which interfaces are connected to the netgear switch. 

3. Finally the speed decrease is observed only on the cisco switch not on the netgear switch. When I originally posted this I thought I noticed it on the netgear switch as well.  

Hope this helps,

John

[john19251]

Hello Seb,

I don't know what happened to my response, but here are the answers to your questions. 

1. The switch only has one link to the netgear switch.

2. The netgear switch is unmanaged so there is no available config. 

3. There is one only one interface connected to the netgear switch and the other interface on the cisco switch is used for my PC. 

4. Finally I only notice the slow internet speeds when I am connected to the cisco switch. When I am connected to the netgear switch the internet speeds are normal. 

Thanks,

John

[Martin Aleksandrov]

Hi,

In addition to Seb's reply bare in mind you must not loop two switches (have two interfaces both connected to the Nether). Although 250 is STP enabled, the Netgear is not aware of any STP so this may cause switching loop.

Regards,

Martin

[john19251]

Hello,

To answer your question the only two ports that are in use is one going to the netgear switch and the other going to my PC.

Hope this helps,

John

[cyberconsultants]

Is the Netgear connected to the next hop out (i.e. is the Netgear directly connected to a router)? If so, is it possible to reverse the order and put the CBS250 in front of the Netgear?

How many links are connected on the Netgear besides the CBS250, and what kind of other hosts/devices are connected to it?

Are these the only two switches in your environment?

[john19251]

Hello,

The netgear switch is the next hop out to the router. Unfortunately I can't put the CBS250 in front of the netgear switch until Friday morning.

There are four other unmanaged netgear switches connected to the switch before the router. (The netgear switch the cisco CBS250 is connected to.) 

The hosts that are connected to the environment are PCs/Printers. 

Finally these aren't the only two switches in the environment. See answer to previous question. 

Thanks, 

John

[cyberconsultants · Accepted solution]

Good! We thought you might reply with something like that!

Two things to consider:

1.) You'll definitely want to put the CBS250 in that 'first position.' Each of your Netgears should then connect via a single link each 'up' to it.

2.) In that same vein, none of the Netgears should be connected to one another. If absolutely necessary to connect Netgears together, then the only links should be Netgear-to-Netgear-to-CBS250. Avoid connecting any two Netgears together that both then connect back up to the CBS250.

Even better would be to consolidate switching as much as possible by eliminating altogether as many of the Netgears as is feasible. Your current design is rife with switching loop potential, which Seb and Martin immediately honed in on.

[Martin Aleksandrov]

@john19251 

Cyberconsultants is absolutely correct in his advice. Just redesign as advised and you'll definitely fix the issue.

Regards,

Martin

[john19251]

@Martin Aleksandrov,

Thanks for your help. I am going to do some cabling tomorrow morning and post the outcome. 

John

[john19251]

@cyberconsultants ,

Thank you very much with your help!

Recently a old cisco switch malfunctioned. In order to get the network back up I used one of the netgear switches we had deployed as the switch in the first position. Made sure there wasn't any switching loops.  Then I bought this cisco switch to replace the other switch. When the new cisco switch arrived I waited to put the new switch at the first position until I could confirm that it worked. So I attached it to the netgear switch in the first position. That is when I noticed the speed test decrease and posted here. I am glad to hear that making it the switch in the first position is going to fix my problem. Now to address consolidating the network. This switch is the first switch replacement, shortly all of the other netgear switches will be replaced with this model. I want to make sure I can keep the same design when I receive the other cisco switches. When I receive the new switches I will place each of them on the cisco switch that is in the first position. So when all is said and done I will have the Cisco switch we just troubleshooted as the main switch and 5 new cisco switches attached to the main switch via one link each. Tomorrow morning I will do some cabling and post the outcome. Hopefully everything goes as planed.

Thanks again for your help. 

John

[john19251]

Thanks everyone for your contribution!

The current question is resolved. 

John