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Ask the Expert- SD-WAN

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Beginner

Question about how to use cisco 3750 switches on a simple brighthouse modem in Orlando Florida

Hello,

I reset the switch using these configurations (sensitive information was changed), yet when I plug in the internet cable to the console port on the back, and plug in the computer on the front with cat 6 cables, the internet does not pass through it.  Why is this happening :-(?

Here is how I reset the switch...is there anything else that I need to do??

HOW TO RESET THE CISCO 3750 TO THE BOOT SCREEN
flash_ini
dir flash:
delete flash:private-config.text
delete flash:multiple-fs
delete flash: config.text
boot
Host Name: BB1
Enable Secret: BB1!
Enable Password: BB1
Virtual Network Password: BB1
Interface Name: Vlan1
Configured IP: 192.168.1.155
Subnet mask: 255.255.0.0

Select 2 and hit enter for it to save...

So, what else am I missing here??

4 ACCEPTED SOLUTIONS

Accepted Solutions
Contributor

The console port is a serial

The console port is a serial port and not an ethernet port and that is an important distinction.  If you are just trying to use the switch as a switch (and not a router) just plug everything into switch ports and assuming your BH modem does DHCP, NAT, etc. you should be good to go.

-- please remember to rate and mark answered helpful posts --
Highlighted
Contributor

It's hard to say with limited

It's hard to say with limited info, but I suspect you need to do more than just plug cables in the correct place.

In general you take the cable from the ISP modem and plug it into the WAN/internet port of a firewall or router.  Then plug LAN port from router to a switch port and computers into other switch ports.

Since it seems you have done that and it is not working there is more troubleshooting to do.

There are so many possible reasons this isn't working for you I don't even know where to begin, unfortunately.

Have you been able to confirm your internet works by connecting a computer directly to the modem?  If so is the modem providing DHCP?  And is it serving you a public or private IP?

-- please remember to rate and mark answered helpful posts --
Rising star

Are you connecting a modem to

Are you connecting a modem to the switch or a router?, there is a difference

Modems are often there to terminate the ISP connection but may not provide the routing and NAT functions which are needed to get an internet connection.

Are your hosts getting DHCP information from the Brighthouse or are you setting them manually?

What is the hosts default gateway? Can they ping it?

At the moment the Cisco will be acting as a basic L2 switch so assuming your Brighthouse is a standard ISP router (not modem only) then this setup should work.

If you plug a host into the Brighthouse directly, does it work?

Thanks

Beginner

Try resetting the switch this

Try resetting the switch this way:

1. power the switch down

2. power the switch back up while holding the "mode" reset button. Wait up to 15 seconds or more until SYST LED turns solid green

3. release "mode" button, the green light will blink

Wait for the switch to start up, plug your RV router into any switchport and your computer into another

You really don't need to touch "console" port

7 REPLIES 7
Contributor

The console port is a serial

The console port is a serial port and not an ethernet port and that is an important distinction.  If you are just trying to use the switch as a switch (and not a router) just plug everything into switch ports and assuming your BH modem does DHCP, NAT, etc. you should be good to go.

-- please remember to rate and mark answered helpful posts --
Beginner

Hey,

Hey,

When I plugged in the internet cat 6 cable (came from Arris TG852 modem to cisco rv110w to 3750 switch) to one of the front ethernet ports, and then in ethernet port 2, I put the cat 6 cable from the 3750 to the i7 computer, it would not pass internet.  Am I still doing something wrong with my cable assignment??

Thanks,

Walter Hnot

Highlighted
Contributor

It's hard to say with limited

It's hard to say with limited info, but I suspect you need to do more than just plug cables in the correct place.

In general you take the cable from the ISP modem and plug it into the WAN/internet port of a firewall or router.  Then plug LAN port from router to a switch port and computers into other switch ports.

Since it seems you have done that and it is not working there is more troubleshooting to do.

There are so many possible reasons this isn't working for you I don't even know where to begin, unfortunately.

Have you been able to confirm your internet works by connecting a computer directly to the modem?  If so is the modem providing DHCP?  And is it serving you a public or private IP?

-- please remember to rate and mark answered helpful posts --
Beginner

Hello Good Sir,

Hello Good Sir,

I have tested all the cables, and it works directly from the router, although not from the 3750 switch.  I have reset multiple 3750 switches, and all of them seem to have the same issue, while they were all from different parties that I purchased them, ergo, I think the tech issue is on my end of the bargain.  There is no issue with the modem providing a DHCP, and I have tried assigning the 3750 switch in the initial configuration, and also just typing no to that section.  Neither of those seem to work.  Is there something wrong with the subnet mask when it comes to being too many layers down or up the chain?

Thanks,

Walter

Beginner

Hello,

Hello,

By following all of your suggestions, I have been able to get it to work.  Thank you all!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Walter

Rising star

Are you connecting a modem to

Are you connecting a modem to the switch or a router?, there is a difference

Modems are often there to terminate the ISP connection but may not provide the routing and NAT functions which are needed to get an internet connection.

Are your hosts getting DHCP information from the Brighthouse or are you setting them manually?

What is the hosts default gateway? Can they ping it?

At the moment the Cisco will be acting as a basic L2 switch so assuming your Brighthouse is a standard ISP router (not modem only) then this setup should work.

If you plug a host into the Brighthouse directly, does it work?

Thanks

Beginner

Try resetting the switch this

Try resetting the switch this way:

1. power the switch down

2. power the switch back up while holding the "mode" reset button. Wait up to 15 seconds or more until SYST LED turns solid green

3. release "mode" button, the green light will blink

Wait for the switch to start up, plug your RV router into any switchport and your computer into another

You really don't need to touch "console" port

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