Hello! Internet works only on one device out of 3

[mxl]

Hello! The Internet works only on one device out of 3, in the manual I can’t find out about it! I would be glad to advice on my question.

my switch cisco sg250-08

Thank you

mxl

[Georg Pauwen]

Hello,

is the SG250 the DHCP server ? What are the IP addresses of your three devices ?

[mxl]

Hello! the wire from my provider goes to the switch, 3 devices are connected to my switch, but the Internet is on one device! I have a DHCP connection from my provider. all three devices are connected via DHCP

mxl

[balaji.bandi]

Hello! the wire from my provider goes to the switch, 3 devices are connected to my switch, but the Internet is on one device! I have a DHCP connection from my provider. all three devices are connected via DHCP

What is the ISP delivery direct Ethernet ? the device working what IP address, the device not working what IP address out of 3 devices.

Looks like you getting the DHCP from the provider for 1 Device that is working i guess, post-show run from the device to understand.

Note: SG is a switch, not do any NAT here.

[mxl]

Hello! "What is the ISP delivery direct Ethernet" -- I am new to networks, I did not understand you, sorry.

"the device working what IP address, the device not working what IP address out of 3 devices." --all 3 devices are configured for dhcp

"Looks like you getting the DHCP from the provider for 1 Device that is working i guess, post-show run from the device to understand." -- I have internet only through dhcp, please tell me what is  "post-show run"

mxl

[balaji.bandi]

Login to device using ssh

issue a command  below and post here

#show run

# show ip interface brief

[Georg Pauwen]

Hello,

it won't work if the ISP link goes directly into the switch. Only one of the devices will get a public IP address, the others won't.

You need a router in between the switch and the ISP link in order for all three devices attached to the switch being able to access the Internet.

[mxl]

Excuse me! my switch sg250 is not a router??

mxl

[Georg Pauwen]

Hello,

I am not sure I am following. Your switch is not a router, that is correct. Since your switch is a switch and not a router, you cannot connect one ISP line to the switch and expect three attached devices to get an IP address. Only one device will get an IP address. You might as well not use the switch, but hook the Ethernet cable from the ISP right into one of your PCs, and the outcome would be exactly the same.

You need a layer 3 device capable of doing NAT between the switch and the ISP line in order for multiple hosts to be able to reach the Internet.

[mxl]

my swicth sg250 08 is a layer 3 device!

" Layer 3 static routing: This capability allows you to segment your network into separate workgroups and communicate across VLANs without degrading application performance. As a result, you can manage internal routing with your switches and dedicate your router to external traffic and security, helping your network run more efficiently. "

mxl

[balaji.bandi]

yes, we totally agree with you, that the switch you have support Layer 3 segmenting the LAN to different networks.

But it does not do NAT here.

[mxl]

if I understand correctly, my switch sg250 does not support NAT? I need a switch sg250 that supports NAT  so that I have an Internet connection on my 3 devices?

mxl

[balaji.bandi · Accepted solution]

 my switch sg250 does not support NAT?

yes correct.

If the provider offers more IP address, you can use all 3 devices, switch act as a switch for those  devices  connected

If the provider offers you 1 DHCP IP, the rest 2 will not be going to work, you need any small router which can NAT here.

[mxl]

Thank you very much!

Sincerely,

mxl

[mxl]

Please tell me how to find out if there is NAT in the device or not?)

mxl